A review on enhancing water productivities adaptive to the climate change

Climate change has led to unpredictable seasonal variations globally. In tropical regions, the noticeable shift in rainy and dry seasons necessitates careful consideration by plant cultivators to anticipate potential water surpluses and deficits (Nikolaou et al. 2020). Accurate observation and analysis of climate data has become increasingly crucial to understand past climate patterns and seasons, particularly in terms of rainwater availability. Reliable information on plant water requirements, especially during cultivation, is essential for determining the appropriate irrigation volume and intensity (Patle et al. 2020; Felipe et al. 2023; Adamkulova & Aitbaev 2024). Recognizing that crop water needs vary based on climatic conditions, soil, and plant characteristics, the applied irrigation technology must respond to soil water reduction caused by plant consumption and replenish it at the right quantity and time (Adeyemi et al. 2017; Koech & Langat 2018).

Enhancing water productivity in agriculture adapting to climate change requires a multifaceted approach. Key strategies include the development and promotion of drought-resistant crop varieties that thrive in changing climate conditions. Precision agriculture techniques, such as drip irrigation and variable rate application of inputs, can optimize water use (Bwambale et al. 2022; Hadri et al. 2022). Upgrading irrigation systems to more efficient methods, alongside rainwater harvesting techniques, helps conserve water during wet periods for later use. Soil management practices, like mulching and cover cropping, enhance water retention and improve soil structure (Haruna et al. 2020; Kocira et al. 2020). Implementing climate-smart agricultural practices, incorporating water-efficient technologies, and capacity-building for farmers are essential. Supportive policies promoting sustainable water management and incentives for adopting climate-resilient practices play a critical role.

Ongoing research and innovation, coupled with community engagement, contribute to resilient agricultural systems capable of withstanding the challenges posed by climate change. Our ongoing research has resulted in the development of an evapotranspirative irrigation technology model (previously unavailable) designed to be adaptive to any climate condition, and responsive to plant evapotranspiration (Muharomah et al. 2023). Its performance has been tested on various plant types. Plants require an appropriate and timely water supply to achieve optimal production. The determination of plant water requirements relies on factors such as climatic conditions, soil properties, and the specific characteristics of the plants. The plant's evapotranspiration rate (ETc) serves as a hydraulic measure used to estimate the rate at which plants consume water (Muharomah et al. 2017).

Numerous models exist for potential evapotranspiration (ETp), with one notable example being the Penman–Monteith (PM) model, renowned for its comprehensive set of input variables (Allen et al. 1998). A more straightforward alternative is the Hargreaves (HG) model, requiring only three input variables, and its outcomes closely resemble those of the PM model (Arif et al. 2012; Hasanah et al. 2015). As a result, the HG model is more adaptable for application in diverse regions of Indonesia, especially where daily climate data is not extensively available. By subtracting the daily rainfall (R) from the historical ETp rates obtained from climate data over the past decades, it reveals patterns of rainy and dry seasons, along with insights into water surplus and deficit periods (Setiawan 2020). Identifying the maximum water deficit helps determine the required irrigation water and suitable cropping patterns aligned with the irrigation water availability.

The supply of irrigation water aims to replenish the soil water reduced by plant consumption. This positions ETc as the guiding factor for water movement within the Soil Plant Atmosphere Continuum (SPAC) model, encompassing water sources, irrigation networks, planting media, plants, and the air (Pereira et al. 2020). The presented irrigation model operates based on this mechanism and is termed as evapotranspiration irrigation (Evapotranspirative Irrigation). It exhibits a maximum capability to supply water matching the highest evapotranspiration rate during extended dry periods. Key success indicators are reflected in land productivity and water productivity, encompassing crop water, irrigation water, and total water (combining rainwater and irrigation water).

The aim of this review is to assess the implementation of irrigation technology and its impact on water use efficiency, examine the application of the smart irrigation system as a management approach, and introduce evapotranspirative irrigation technology tested in the same location with diverse crops and designs. Through this review, the study aims to demonstrate that evapotranspirative irrigation technology can reduce crop water consumption, improve water use efficiency, and contribute to increased land and water productivities in response to the impacts of climate change.

This paper presents a comprehensive review aimed at exploring diverse approaches and technologies that enhance water productivity in agriculture, fostering adaptive strategies to address the challenges posed by climate change. The focus is on innovative irrigation technologies, smart irrigation systems, and evapotranspirative irrigation methods, which play pivotal roles in optimizing water use efficiency and promoting sustainable agricultural practices.

Through a comprehensive examination of these approaches, this review seeks to provide valuable insights into the practical implementation and potential synergies between irrigation technologies, smart systems, and evapotranspirative methods. The findings are anticipated to contribute significantly to the ongoing discourse on sustainable water management strategies in agriculture and support the development of adaptive measures to mitigate the impact of climate change on global food production.

Our review sought to systematically analyze the literature on irrigation technologies and systems designed to enhance water efficiency and increase productivity, adaptive to climate change. A comprehensive search strategy was employed to locate relevant articles from multiple sources, such as academic databases, government repositories, and key study reference lists. Keywords were carefully chosen to encompass a wide scope of literature focusing on the role of irrigation technology in climate change adaptation. Articles were selected based on predefined criteria emphasizing relevance and quality. Specifically, we included studies that examined the impact of climate change on water productivity in Indonesia, as well as those that explored the current stage of irrigation technology adoption and the challenges faced by smallholder farmers. The following research questions were formulated: (i) How is irrigation technology and water use efficiency progressing globally? This review delineates two key approaches. The first is grounded in water balance and water yield models, while the second relies on information regarding crop water demand and a comprehensive consideration of the water-yield–quality relationship. Additionally, this review offers a theoretical foundation and decision-making guidance for research innovation and agricultural production. (ii) What are the current smart irrigation and management systems that could enhance water productivity? (iii) How effective are these adaptive measures in reducing vulnerability and building resilience in food systems? (iv) What is the current state of irrigation technology adoption and what challenges do smallholder farmers in Indonesia face? and (v) What are the latest innovative irrigation technologies that could be introduced to farmers in Indonesia as potential solutions? The review prioritized studies with strong research methodologies, including empirical research, case studies, and review articles, to ensure high-quality evidence.

The search strategy involved using electronic databases like Web of Science and Google Scholar, combining keywords such as ‘irrigation technology’, ‘smart irrigation system’, ‘water use efficiency’, ‘water productivity’, and ‘Indonesia’. No restrictions were placed on publication date, language, or study design, aiming to capture a broad and relevant range of literature. In addition, citation-tracking techniques were used to identify any relevant studies that might not have been captured in the primary search.

Irrigation technologies and water use efficiency vary across countries based on factors such as climate, available water resources, agricultural practices, and technological advancements. It is important to note that advancements in irrigation technologies continue, and countries are increasingly adopting sustainable and efficient practices to address water scarcity challenges. Local conditions and policies play a significant role in shaping irrigation practices in each country.

A modeling study on irrigation technology in Southern Alberta, Canada, focusing on water trading, irrigation technologies, and crop choices at a macro level has been conducted by Danso et al. (2021). The primary goal was to assess the adoption gains from water trading by integrating various irrigation technologies and considering different crops across diverse land qualities. The study encompassed six irrigation technologies and 12 crops to analyse how water-trading influenced adoption decisions. The findings of the study revealed that farmers tend to adopt a rational approach, utilizing the gains from water trading to implement more efficient irrigation technologies. This inclination is particularly evident when the net gain surpasses the costs associated with adopting a specific irrigation technology. Simulation analysis, however, indicated limited potential for transitioning to more efficient irrigation technologies under full water allocation scenarios. Nonetheless, sensitivity analysis underscored the potential influence of factors such as high crop prices and subsidies on the adoption of improved irrigation technologies, making it more appealing for farmers to adopt technologies that enhance crop profitability through water trading. The study suggests that effective policies aimed at providing incentives for farmers to adopt efficient irrigation technologies and enhance crop yields may be crucial for the study area. This highlights the importance of aligning economic factors, such as crop prices and subsidies, with water trading practices to encourage the adoption of advanced irrigation technologies and ensure sustainable agricultural practices in Southern Alberta.

Speelman et al. (2008) and Eshete et al. (2020) conducted a comprehensive study and review focusing on irrigation water use efficiency in Africa. Their findings highlighted several factors that significantly influence water use efficiency, including farm size, landownership, fragmentation, the type of irrigation scheme, crop selection, and the methods of irrigation employed. This information holds considerable value for extension services and policymakers, offering insights that can guide policies toward enhancing overall efficiency in water use.

It is recommended that appropriate regulations be established to restrict water allocation and usage, ensuring a sustainable approach. To address this, governments and collaborating partners should allocate resources for capacity-building initiatives aimed at educating farmers about effective irrigation practices, ultimately leading to improved water use efficiency. Despite the longstanding practice of irrigation by farmers, the transition beyond subsistence farming has not been achieved. Additionally, advancements in irrigation water use efficiency, particularly through proper scheduling and on-farm management, have not yielded satisfactory results.

A notable observation is that, in cases where water is conserved through the efficient use of technologies, the surplus water tends to be utilized for expanding the irrigation area, consequently increasing household income. To achieve a net gain in water savings, it is emphasized that water-efficient technologies and practices should be integrated with other measures, such as incentives for conservation and appropriate regulations, thus ensuring a holistic and sustainable approach to irrigation water use.

In the Mediterranean region, enhancing irrigation technologies holds significant potential for water conservation, and the exploration of optimal and cost-effective irrigation management practices can effectively mitigate water scarcity concerns (Fader et al. 2016; Udias et al. 2018). Water scarcity and droughts are predominant challenges in most Mediterranean countries, with agriculture being a major consumer of both surface and groundwater. The substantial release of water in agriculture poses a threat to the sustainability of water resources in the region. Currently, the Mediterranean region has the potential to save up to 35% of water by implementing more efficient irrigation and conveyance systems. This could result in a reduction of irrigation water volumes by 32%–70%, while maintaining existing agricultural benefits. The implementation of specific management strategies is also considered a viable approach to optimizing crop benefits while simultaneously reducing overall water usage. An estimated optimal reallocation of water could lead to a 52% (148 Mm³/year) reduction in irrigation water volumes, accompanied by a 7% (48M€) decrease in agricultural income, yet maintaining the current agricultural benefits valued at 626.9M€. Improved irrigation technologies and conveyance systems are crucial in unlocking significant water-saving potential and may act as a compensatory measure for the challenges posed by climate change and population growth. This study underscores the importance of identifying optimal, cost-effective irrigation management strategies to effectively address the critical issue of water scarcity, particularly for sustaining agriculture in the Mediterranean region.

Implementing advanced irrigation technology in China has the potential to enhance water efficiency and contribute to water and energy savings (Zhi 2002; Zhang et al. 2013; Li et al. 2016; Zhou et al. 2020). Water-efficient irrigation practices are recognized for sustainable improvements in water productivity. The adoption of technologies promoting the efficient use of irrigation water and energy could yield substantial energy savings, reaching up to 20% compared with conventional irrigation methods in China. The proposed integrated high-efficient irrigation strategy, outlined in this review, marks a transition from traditional field irrigation practices to a new era of irrigation management aimed at water conservation and quality enhancement, particularly for cash crops.

Fan et al. (2020) conducted a study on improving nutrient and water use efficiencies through water-drip irrigation and fertilization technology in northeast China. This innovative approach involves the simultaneous application of fertilizer and water through precision irrigation, ensuring precise and accurate nutrient delivery. Over two years, precision fertilization management led to a reduction in nutrient supply without adversely affecting maize growth or grain yield. In 2015, precision fertilization management reduced nitrogen and phosphorus supply by 8% and 10%, respectively, while increasing potassium supply by 15%. In 2016, the reduction percentages were 9% for nitrogen, 25% for phosphorus, and 17% for potassium. Importantly, maize plant height, leaf area index, aboveground biomass, and yield did not significantly decrease despite the reduced fertilizer application. As a result, precision fertilization management increased nutrient and rainfall use efficiency, leading to enhanced net-profit. This study underscores the significance of fertigation in boosting maize production, thereby contributing significantly to overall food production.

A study on response of growth, yield and water use efficiency of winter wheat to different irrigation methods and scheduling in North China Plain (NCP) was also done by Kumar Jha et al. (2019). Enhancing agricultural water use efficiency is crucial for farmers in the NCP facing a severe water shortage that threatens winter wheat (Triticum aestivum L.) production. A two-season field experiment was conducted in a winter-wheat field to assess the effectiveness of three irrigation methods: sprinkler irrigation (SI), surface drip irrigation (SDI), and flood irrigation (FI), each implemented under three irrigation schedules. The schedules involved irrigating when soil moisture decreased to 70%, 60%, and 50% of the field capacity, respectively. The findings revealed that the combination of suitable irrigation methods with effective scheduling has the potential to achieve an optimal balance between yield and water use efficiency. The results indicated that applying 180.3 and 175.2 mm of water in the two studied seasons, respectively, was optimal for achieving the highest grain yield. In the case of SDI and SI, this could be achieved by six irrigation sessions, each providing 30 mm of water. Meanwhile, for FI, comparable results were obtained by irrigating three times, each with 60 mm of water. The study suggested that irrigating when soil moisture decreased to 60% of the field capacity through SDI yielded the best overall outcomes compared with other irrigation methods and schedules.

Qiu et al. (2021) reported the impact of water and salinity stress on the dry matter (DM) and water use efficiency (WUE) of alfalfa in the arid and semi-arid regions of northwest China. With the increasing cultivation of alfalfa on salinized soils in these regions, it is crucial to comprehend how alfalfa responds to soil salinity stress under deficit irrigation. The study, conducted through a test-pit experiment in 2016 and 2017, involved 12 treatments comprising three water levels (full – W1, medium – W2, and low irrigation – W3) and four salinity levels (S0–S3) with varying salt addition rates. Throughout the growth period, soil water content (SWC) and soil electrical conductivity (ECe) were regularly measured, and DM and WUE for the second and third cuts of each year were presented. Both water and salinity stress were found to significantly impact alfalfa DM and WUE for individual cuts as well as the combination of the two cuts each year, with consistently insignificant interactions. DM and WUE exhibited continuous reduction with lower irrigation water and increased salinity stress in both years. On average, DM reduction was approximately 20%, 30%, and 58% for S1, S2, and S3, respectively, relative to S0, while the reduction was 21% and 34% for W2 and W3, relative to W1. Simultaneous exposure to water and salinity stress had more detrimental effects on DM and WUE than single stress factors. Total alfalfa DM showed a linear correlation with average ECe over the growth period, with an R² greater than 0.8, suggesting that ECe serves as an effective predictor for estimating alfalfa yield on saline soils in the region. These results provide valuable insights into evaluating soil productivity in saline areas and the effectiveness of potential remedial measures.

Kothari et al. (2019) conducted a simulation study focusing on efficient irrigation management strategies for grain sorghum production under varying climate variability classes in the Texas High Plains (THP). The THP heavily relies on the Ogallala Aquifer for irrigation water, making efficient water use crucial for sustainable agriculture. Grain sorghum, known for its drought tolerance and lower water requirements compared with crops like corn, is a major crop in the region. The study utilized the CERES-Sorghum and CROPGRO-Cotton modules of the Decision Support System for Agrotechnology Transfer (DSSAT) based on data from cotton–sorghum rotation experiments in Halfway, Texas, spanning nine years (2006–2014). The evaluated CERES-Sorghum model was employed to determine optimal factors for irrigation strategies, including initial soil moisture at planting (ISM), threshold to start irrigation (ITH), threshold to terminate irrigation, and deficit/excess (DFI) irrigation strategies. These factors were identified based on simulated sorghum yield, irrigation water use efficiency (IWUE), and grain water use efficiency (WUE). Long-term simulations revealed the significant influence of weather conditions on the selected irrigation management strategies. Weather conditions were categorized into cold, warm, wet, dry, and normal climate variability classes based on growing season temperature and precipitation percentiles. The DSSAT model effectively simulated grain sorghum and seed cotton yields during calibration and evaluation. The results highlighted that weather conditions played a pivotal role in determining appropriate irrigation management strategies. Under normal/cold/wet conditions, an ISM of 75% available water holding capacity (AWC), ITH of 50%, and DFI at 85% were found suitable for irrigated grain sorghum production. Conversely, in warm/dry weather, an ISM of 75%, ITH of 60%, and DFI at 100% reduced sorghum yield loss.

Garibay et al. (2019) adopted more efficient irrigation strategies. The Decision Support System for Agrotechnology Transfer (DSSAT) is a model that relies on meteorological, soil, and crop management data to forecast crop growth, development, and yield. The robust evaluation of the CROPGRO-Cotton module within the DSSAT model is crucial for simulating effective crop and irrigation management strategies. This study provides a comprehensive assessment of the CROPGRO-Cotton module, utilizing measured in-season biomass, canopy height, and crop yield data from a field study. The evaluated model is then applied to identify the optimal irrigation strategy for cotton (Gossypium hirsutum L. var. hirsutum) in terms of crop yield and irrigation water use efficiency. Irrigation simulation experiments were conducted, exploring four distinct irrigation scheduling strategies – time temperature threshold (TTT) at 5.5 h, TTT at 7.5 h, daily irrigation (DI), and percent ET replacement. The goal was to determine the most efficient irrigation strategy that maximizes yield with minimal irrigation water input. The DSSAT CROPGRO-Cotton model demonstrated its capability to simulate the impacts of various irrigation strategies on cotton yield and water use efficiency. The 12 mm, 7.5-h TTT strategy emerged as the most effective, yielding a modeled 5,887 kg ha⁻¹ using 195 mm of irrigation throughout the season, achieving maximum yield with optimal irrigation water use efficiency.

Katuwal et al. (2020) investigated the soil water extraction patterns and water use efficiency of spring canola (Brassica napus L.) under a deficit irrigation strategy. They cultivated three different canola cultivars, subjecting them to four distinct irrigation treatments: full-season irrigation, no irrigation at the vegetative stage, no irrigation at the reproductive stage, and dryland conditions. In the wetter year of 2015, Treatment VS exhibited a comparable total water extraction (20 mm) from planting to harvest as full-season irrigation. The canola plants in Treatment VS sustained vegetative growth by efficiently utilizing soil water extraction, and during the reproductive stage, they optimally used irrigation to reduce seasonal evapotranspiration compared with full-season irrigation. Treatment reproductive stage and dryland also reduced seasonal evapotranspiration; however, they resulted in an average 11% and 13% reduction in oil content compared with full-season irrigation in 2015 and 2016, respectively. Treatment VS demonstrated similar oil content to full-season irrigation, showcasing optimized water use efficiency for biomass (WUEpb), seed (WUEsy), and oil (WUEoy) yields. The study suggests that adopting spring canola cultivation and omitting irrigation during the vegetative stage could enhance water productivity in water deficit conditions of the SGP.

Haghverdi et al. (2021) devised strategies for conserving irrigation water for hybrid bermudagrass using an evapotranspiration-based smart irrigation controller in inland southern California. Over a three-year period (2017–2019), an irrigation research trial was conducted to assess the impact of various irrigation scenarios on hybrid bermudagrass and evaluate the effectiveness of the Weathermatic evapotranspiration-based (ET-based) smart controller for autonomous landscape irrigation management during dry seasons in inland southern California. The applied irrigation levels ranged from 39% to 103% of reference ET (ETo), with irrigation frequency restrictions of three, five and seven days per week. Continual collection of Normalized Difference Vegetation Index (NDVI) data was employed to evaluate the response of hybrid bermudagrass (‘Tifgreen’ Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy) to the various irrigation treatments. Visual assessments were also conducted, following National Turfgrass Evaluation Program (NTEP) standards, on a scale from 1 (dead plot) to 9 (ideal turfgrass). The Turfgrass Water Response Function (TWRF), introduced as a statistical regression model, was utilized to estimate hybrid bermudagrass quality response (NDVI values) to different irrigation levels over time. Significant effects of irrigation levels on NDVI values were observed in 2018 (p < 0.01) and 2019 (p < 0.001), while irrigation frequency restrictions did not show a significant impact on NDVI in any of the years. A high correlation (r = 0.84) was noted between visual rating (VR) and NDVI data. The TWRF exhibited high accuracy (RMSE = 0.047, no units), and estimated NDVI values demonstrated a strong correlation (r = 0.89) with measured NDVI values. A comparison between the California Irrigation Management Information System (CIMIS) reference evapotranspiration (ETo) and temperature-based ETo estimations by the controller revealed that the smart controller, on average, over-irrigated by 12%, 2%, and 3% throughout the experimental periods in 2017, 2018, and 2019, respectively. Long-term analysis (34 years) using CIMIS ETo data and the TWRF model indicated that 75% of ETo is the minimum irrigation application required to maintain acceptable hybrid bermudagrass quality in the inland southern California semi-arid climate during months with high irrigation demand (i.e., May to November). The results also suggested that hybrid bermudagrass could withstand more severe deficit irrigation treatments for shorter periods, depending on ETo demand.

The technical aspects of enhancing water and energy efficiency in the modernization of irrigation have been explored by Tarjuelo et al. (2015). The intricate balance between water and energy efficiency becomes particularly evident when transitioning from open-channel, gravity-based systems to pressurized distribution networks and shifting from surface to pressurized irrigation systems – a prevalent modernization approach in Spain and other nations. This overview emphasizes strategies and technologies aimed at optimizing water and energy utilization in irrigation, along with key models and tools for enhancing the design and management of irrigation infrastructure. Calculations measuring water conservation and energy consumption resulting from these improvements illustrate the intricate interplay between energy and water efficiency. While irrigation modernization brings benefits such as increased water efficiency and productivity, enhanced operation and management of irrigation systems, and improved working conditions for farmers, it also entails heightened energy demands and investment requirements. It is crucial to conduct a thorough analysis of the economic, social, and environmental feasibility of the irrigation modernization process in each specific case. Effective design and management of irrigation systems, alongside the promotion of Irrigation Advisory Services and Web-GIS platforms for the real-time transfer and sharing of information with farmers in a feedback loop, emerge as essential tools for optimizing the consumption of water, energy, and other production inputs.

According to Büyükcangaz et al. (2007), making irrigation more efficient in Turkey is both necessary and highly desirable. The plans of the General Directorate of State Hydraulic Works (DSI) to transform open channel systems and elevated canals into closed conduits or pipeline systems are crucial for optimizing land and water utilization. There are more efficient and environmentally sustainable technologies, such as pressurized irrigation systems (sprinkler, drip, mini sprinkler, etc.), which have the potential to reduce water demand and enhance irrigation efficiency. If pressurized irrigation systems were implemented nationwide, an additional 25.85 million hectares of land could benefit from irrigation. However, achieving broader adoption of these systems requires addressing the fragmented landholding structure.

Koech & Langat (2018) conducted a review focusing on the progress made in enhancing irrigation water use efficiency (WUE), particularly in Australia, supplemented with examples from other nations. The review delves into both the challenges faced and the opportunities presented in this context. The findings reveal that enhancements in irrigation infrastructure, driven by modernization and automation, have resulted in significant water savings. Although the concept of real-time control and optimization in irrigation is still in its early stages, it has shown promise for conserving water. The future is anticipated to witness a growing reliance on remote-sensing techniques, wireless communication systems, and more adaptable sensors to further improve WUE.

Cai et al. (2021) have introduced an effective water-saving irrigation technology as a primary approach to sustain apple production and prevent land degradation. Subsurface irrigation with ceramic emitters (SICEs) emerges as an energy-efficient and water-saving solution, particularly suitable for arid and semi-arid regions. However, the adaptability and efficacy of SICE for apple trees need thorough investigation, especially considering the unique environment of the Loess Plateau. This study aimed to identify the optimal buried depth of SICE tape by evaluating SWC, apple-tree yield, water use efficiency (WUE), and irrigation water use efficiency (IWUE) over a two-year field experiment. The results revealed that burying SICE at a depth of 40 cm led to a significant improvement in new shoot length, yield, WUE, and IWUE, demonstrating increases of 15.9%, 7.6%, 14.8%, and 6.5%, respectively, compared with subsurface drip irrigation (SDI). Notably, variations in SWC for SICE at a 40 cm depth were smaller than those observed for SDI. The effectiveness of SICE in enhancing yield was attributed to its capacity to conserve water and elevate soil temperature for apple trees. This study underscores that SICE not only creates a suitable soil water environment to ensure the stable growth of apple trees but also contributes to substantial water resource savings.

However, a noteworthy observation is that, in many instances, the water saved through efficient technologies often leads to the expansion of irrigated land, potentially resulting in a net increase in total water consumption at the basin scale. Therefore, for genuine water savings, water-efficient technologies and practices must be complemented with other measures like incentives for conservation and appropriate regulations governing water allocation and usage. Various factors influencing trends in irrigation WUE encompass engineering and technological innovations, progress in plant and pasture science, environmental considerations, and socio-economic factors. Challenges may arise, including a lack of public support, especially when cost-effectiveness is not evident, and the resistance of irrigators to adopting new technologies.

Smart irrigation system refers to an advanced and automated approach to water management in agriculture that leverages technology to optimize the irrigation process. This system integrates various technologies, such as sensors, data analytics, and communication devices, to monitor and control the irrigation process efficiently. The primary goal of a smart irrigation system is to enhance water conservation, improve crop yield, and increase overall water use efficiency.

Darshna et al. (2015) developed a smart irrigation system to address the substantial water requirements in irrigation, aiming to achieve approximately 80% water savings. The prototype is designed to streamline the irrigation process, saving time and alleviating concerns associated with constant monitoring. This system contributes to water conservation by automating the delivery of water to plants or gardens based on their specific water needs. Its potential efficiency extends to applications in agricultural fields, lawns, and parks. With technological advancements, the integration of embedded and microcontroller systems offers solutions to various challenges. In this application, a sensor-based microcontroller system is employed to precisely control the water supply for gardens. Sensors installed in the field monitor soil temperature and moisture, transmitting the data to the microcontroller, which then calculates the water requirements of the plants.

Zhang et al. (2018) devised an irrigation system focused on water conservation, employing water balance theory to address issues related to uneven soil moisture distribution and delayed system-decisions. This paper outlines the theoretical framework of the water balance method, providing insights into the calculation techniques for water supplementation and crop transpiration. Building upon the theoretical groundwork, the paper introduces an intelligent water-saving irrigation control system designed through the Agricultural Internet of Things approach, presenting comprehensive details on both the hardware and software design of the system. The practical application of this system in Xiaotangshan, Beijing, yielded positive results, demonstrating the effective implementation of irrigation through intelligent water-saving methods based on the water balance theory.

Murty & Fauzan (2021) introduced an automated water irrigation system tailored for urban farming, aligning with the progress in knowledge and technology that has positively impacted various industries, including agriculture. Urban farming, a form of agronomy practiced in cities, housing areas, and apartments, focuses on utilizing limited space for cultivating rapidly growing fruits and vegetables. Despite being small-scale and requiring minimal initial investments, urban farming faces challenges, particularly in manual water irrigation using electricity, a non-renewable energy source. The primary goal of this research is to develop an improved small-scale automated water irrigation system for urban farming, incorporating self-sustainability and reliance on renewable energy. The study encompassed three analyses, emphasizing key factors influencing water irrigation systems: renewable energy, flow, and economic considerations. Design elements, such as the use of renewable energy sources (solar, wind, or hydro), pump and motor specifications, pipe size, material, layout, cost, volumetric flow rate, head loss, and actual pressure in pipes, were also considered. Results indicated that hydro energy was the most suitable renewable energy source. A 500 W pump and motor set were found to be optimal for irrigating water in the urban farm, and a 0.3 m underground pipe layout using ¾-inch rubber pipes proved to be the most efficient for the automated water irrigation system. Economic analysis demonstrated that the new design could save up to RM 2,364.58 annually, achieving a return on investment (ROI) within approximately six months and turning a profit within one year. The comprehensive analyses and results suggest that the improved automated water irrigation system for urban farming is not only cost-efficient but also environmentally friendly.

Emharraf et al. (2020) have implemented an intelligent irrigation platform designed to optimize crop yield and water productivity by ensuring precise watering processes. This involves applying a specific amount of water to crops at precise locations and times. The proposed platform utilizes sensory data from various nodes distributed throughout the field, making use of a straightforward approach. The architecture is built around a gateway node and multiple wireless nodes with LoRa connectivity. Each wireless node is linked to diverse sensors, actuators, and a solar panel, providing the node with unlimited autonomy. Industrial sensors, including soil moisture, temperature, and humidity sensors, are employed to measure different parameters related to the soil, plant, and atmosphere. The collected data is transmitted and processed on the gateway node and a remote server, facilitating the storage of sensory data and enabling further versatile consultation and analysis. The platform, characterized by energy autonomy and cost-effectiveness, proves beneficial for geographically isolated and water-limited areas.

A study on the architecture of wireless sensors for effective irrigation water management has also been conducted by Navarro-Hellín et al. (2015). Agriculture relies heavily on water as a vital resource, and in regions with water scarcity and high costs, such as the southeast of Spain, optimal management becomes crucial. Implementing irrigation strategies to enhance the watering process significantly impacts crop profitability. It is essential to instrument variables related to the crop growth process (soil, water, and plant) and employ associated techniques to optimize production. The system proposed in this paper leverages information and communication technologies, enabling users to easily consult and analyse information obtained from various sensors on any device (computer, mobile phone, or tablet). The architecture is built on different wireless nodes with GPRS connectivity, each being fully autonomous and utilizing solar energy for virtually unlimited autonomy. Various commercial sensors, capable of measuring a wide range of parameters related to soil, plant, and atmosphere, can be connected to these nodes. The data are transmitted and processed on a remote server, storing sensor information in a database for subsequent easy and versatile consultation and analysis.

A smart irrigation system based on real-time soil moisture data in a greenhouse has also been developed by Liao et al. (2021). In the present investigation, a smart irrigation system leveraging real-time soil moisture data was developed. The dynamic crop water uptake depth (WUD) was estimated based on the spatiotemporal characteristics of soil moisture distributions. Subsequently, the acquired crop WUD data were utilized by a central irrigation controller to achieve precise irrigation depths at each irrigation event. A drip irrigation experiment involving tomato (Lycopersicum esculentum) cultivation was conducted in a greenhouse in northern China. Wireless soil moisture sensors were strategically placed to collect real-time soil moisture data from 0 to 100 cm of soil profile. The soil moisture exhibited a ladder trend for the 0–60 cm layer and a stable trend for the 60–100 cm layer. A regression equation (WUDi = −0.0119d² + 1.9387d – 6.5795, R² = 0.89) was successfully derived to quantify the dynamic depth of crop water uptake, guided by the characteristics of soil moisture distribution. A water-saving scheme, irrigating based on real-time crop WUD, was established to direct each irrigation event through a remote automatic irrigation system. The tomato evapotranspiration (ET) calculated using soil moisture data aligned with that calculated using indoor meteorological data, validating the reliability of real-time soil moisture data for estimating tomato WUD. The irrigation water use efficiency (IWUE) for tomatoes in the developed system reached 41.23 kg/m³, marking a noticeable improvement compared with a traditional irrigation scheme (31.58 kg/m³). Furthermore, the IWUE of tomato in the established system nearly approached that of previously published results. This study underscores the significance of rational water-saving irrigation scheduling and offers insights into the development of an efficient and automated irrigation system.

Shi et al. (2021) conducted a study on knowledge-driven ‘smart’ irrigation, aiming to achieve targeted crop yield and/or irrigation water use efficiency (WUE). They developed a coupled model integrating crop growth and soil water transport, applying it to schedule irrigation for drip-irrigated and film-mulched maize through numerical simulation. Various scenarios were designed, incorporating either a constant or variable threshold of the plant water deficit index (PWDI) to initiate irrigation. The study investigated the quantitative relationship between the PWDI threshold and the corresponding yield and WUE, ensuring acceptable errors between measured and simulated values (R² > 0.85). The model allowed the determination of PWDI thresholds tailored to specific combinations of yield and WUE, considering factors such as water resource availability and cost. The study found that regulated deficit irrigation (RDI) with a variable threshold, accounting for the variability of physiological response to water stress, outperformed a constant PWDI threshold in improving WUE. They suggested a constant PWDI threshold of 0.54 and identified 45 threshold combinations across various growth stages to achieve similar relative values of yield and WUE. Numerical simulation demonstrated potential in providing reliable dynamic information on soil water and crop growth, essential for smart irrigation scheduling. The approach's ability to integrate environmental conditions and economic considerations makes it promising for optimizing irrigation scheduling in complex situations, warranting further research to enhance simulation accuracy.

A smart irrigation system incorporates several key components and features to revolutionize traditional agricultural water management practices. Field-deployed sensors play a pivotal role by measuring soil moisture, temperature, humidity, and other pertinent parameters, furnishing real-time data to the system. Advanced data analytics processes this information, enabling a nuanced understanding of crop water requirements and facilitating precise irrigation scheduling. Automation is a cornerstone, as the system autonomously regulates irrigation processes based on the analyzed data, overseeing the timing, duration, and volume of water delivered to crops to ensure optimal growth conditions.

Furthermore, these systems often integrate weather forecasts into their algorithms, allowing anticipation of natural precipitation and adjustment of irrigation schedules accordingly. Remote monitoring and control capabilities empower users to oversee and manage the irrigation system from afar through web-based platforms or mobile applications, providing flexibility and swift responses to changing environmental conditions. With a focus on sustainability, smart irrigation systems direct water precisely to the root zone when needed, minimizing wastage, and reducing over-irrigation, thus promoting responsible water use. Some systems embrace energy efficiency by incorporating renewable sources like solar power, reducing reliance on non-renewable energy, and contributing to environmental conservation.

Beyond environmental benefits, these systems lead to cost-savings by optimizing water usage and curbing energy expenses, potentially resulting in improved crop yields. Designed to be scalable, smart irrigation systems cater to various field sizes and crop types, ensuring adaptability to diverse agricultural settings. In the broader context, these systems emerge as critical contributors to sustainable agriculture, addressing challenges associated with water scarcity, enhancing water use efficiency, and championing eco-friendly irrigation practices. As technology evolves, the ongoing advancement of smart irrigation systems plays a pivotal role in modernizing agricultural methodologies and fostering the responsible utilization of vital water resources.

Irrigation system management is a comprehensive approach involving the effective control, monitoring, and optimization of irrigation processes to ensure the prudent utilization of water resources in agricultural practices. The key facets of irrigation system management encompass various critical elements. Water scheduling is a fundamental aspect that involves determining the precise timing and quantity of water application to crops based on factors such as soil moisture levels, prevailing weather conditions, and crop water requirements. This necessitates the establishment of a well-defined irrigation schedule to prevent both under-irrigation and over-irrigation.

Moreover, technology integration is pivotal, entailing the incorporation of advanced technologies like sensors, weather stations, and automation systems. These technologies facilitate the collection of real-time data on soil conditions, weather forecasts, and crop growth, enabling precise and data-driven decision-making. Soil moisture monitoring plays a crucial role in assessing crop water needs by regularly measuring and tracking soil moisture content. This involves deploying soil moisture sensors at different depths within the soil profile. The implementation of automation and control systems is imperative, allowing for the remote control of irrigation systems that can automatically adjust timing, frequency, and duration based on preset parameters or real-time data.

Wang et al. (2020) investigated a water-saving irrigation approach in rice fields, employing three nitrogen (N) application rates (90, 180, 270 kg N ha⁻¹) under two distinct irrigation schemes: (1) the conventional flooding–midseason drainage–flooding irrigation (FDF), and (2) flooding–moist through alternating wetting and drying (AWD) as a water-saving technique. The findings revealed that AWD irrigation led to a notable 38% reduction in CH₄ emissions but a simultaneous 34% increase in N₂O emissions. Despite the trade-off relationship between N₂O and CH₄ emissions, the implementation of water-saving irrigation management resulted in a significant 22% decrease in global warming potential (GWP) and a 24% decrease in greenhouse gas intensity (GHGI). N fertilization positively impacted rice grain yield without affecting water use efficiency (WUE). While AWD did not influence rice grain yield, it did enhance WUE by 40%. Considering the combined effects of N fertilization and irrigation management, the highest grain yield (7,808.38 kg ha⁻¹) was observed in AWD with a medium N application rate. Overall, the AWD irrigation regime emerged as an effective strategy for concurrently conserving water, boosting rice grain yield, and mitigating greenhouse gas emissions from rice paddies.

Meena et al. (2019) conducted research on irrigation management strategies in wheat to optimize water usage in areas facing declining water resources. Wheat holds the position of the second most crucial food crop both in India and globally. In regions dedicated to wheat cultivation, a significant challenge arises from the rapid depletion of water resources. This study aimed to investigate the hypothesis that reducing the amount of irrigation water would sustain the grain yield of the popular Indian wheat variety HD2967. Over three consecutive years, water use, crop yield, and water use efficiency of wheat were assessed across 13 distinct irrigation treatments. The highest yield (5,372.4 kg/ha) was observed when the crop received full irrigation (60 mm of water at all five critical crop-growth stages), a result statistically comparable to yields achieved under 25% deficit irrigation (45 mm) at all growth stages. The treatment with 50% irrigation (30 mm) at all five growth stages, despite conserving 50% water, incurred a significant yield penalty (4,788.1 kg/ha = 10.9% loss). Practices adhering to the normal recommended irrigation amount (60 mm) exhibited lower water use efficiency (WUE) values (1.88 kg/m³), while 25% deficit irrigation, i.e., 45 mm at all five stages, demonstrated significantly higher WUE (2.23 kg/m³) in sandy loam soils. The treatment resulting in a saving of 750 m³ of water per hectare proved to be the most economically viable option, offering cost-savings on water, electricity, and labor. Embracing 45 mm irrigation at all crop growth stages can enhance irrigation water use efficiency without compromising yield, presenting itself as a practical water-saving approach in regions grappling with diminishing water resources.

Hanipah et al. (2020) enhanced the management of water irrigation to improve water usage efficiency. The transformation of land use from agriculture to an industrial city occurred in Karawang, accompanied by an increase in water consumption for industrial purposes. This shift resulted from inadequate water management, particularly in terms of distribution and control, affecting both the industrial and agricultural sectors. The area of irrigated land decreased from 97,037 ha in 2009 to 90,062 ha in 2017, while dry land increased from 22,063 ha in 2009 to 46,299 ha in 2017. This shift demonstrated the adverse impact of insufficient irrigation water management on the reduction of fertile paddy fields. To address this issue, the research aims to develop an action plan for water irrigation management in West Telukjambe District, Karawang Regency. The study utilized stakeholder analysis, incorporating data from observations, interviews, irrigated land area, and the availability of irrigation water. The findings revealed overlapping and missing roles among stakeholders responsible for irrigation water management in West Telukjambe. Model simulations indicated an expansion in the irrigation service area, reflecting improved performance by each stakeholder. Consequently, integrated management of irrigation systems is crucial to regulate distribution and enhance the efficiency of water irrigation.

Adopting water-efficient irrigation methods, such as drip and precision irrigation, is another vital aspect aimed at delivering water directly to the root zone of plants, minimizing water wastage, and enhancing overall water use efficiency. Additionally, weather-based irrigation involves utilizing weather data to make informed decisions, adjusting irrigation plans to account for upcoming weather conditions and natural precipitation. Energy efficiency is addressed by implementing practices such as using renewable energy sources for water pumping and employing energy-efficient irrigation equipment to reduce overall energy consumption. Monitoring and reporting mechanisms are established to regularly assess the performance of the irrigation system, generating reports on water usage, system efficiency, and crop response, aiding in the identification of areas for improvement and informed decision-making.

Irrigation systems play a crucial role as effective entities in addressing the growing need for food, as well as contributing to the advancement, sustainability, and productivity of the agricultural sector. The effective utilization of water resources and the success of crop and orchard production hinge on the design, management, and operation of irrigation systems. Holzapfel et al. (2009) scrutinize knowledge and research that aids in discerning the primary criteria and processes essential for enhancing the design and management of irrigation systems. This is rooted in the fundamental concept that these systems facilitate more efficient and sustainable agricultural development. The design and management of irrigation systems should be grounded in pertinent criteria, encompassing considerations of agronomic, soil, hydraulic, economic, energetic, and environmental factors. Achieving optimal design and management at the farm level is a pivotal factor for the judicious use of water, economic progress in agriculture, and its environmental sustainability.

Furthermore, training and education initiatives are integral, providing farmers and irrigation system operators with insights into best practices, water conservation techniques, and optimal utilization of irrigation technology. Lastly, compliance with local regulations and guidelines related to water use and conservation is crucial, contributing significantly to sustainable water management practices within the realm of irrigation system management.

Micro-irrigation systems represent a modern and efficient approach to water delivery in agriculture, designed to enhance precision and water use efficiency. These systems, also known as drip or trickle irrigation, involve the controlled application of water directly to the root zone of plants through a network of tubing, pipes, and emitters.

Micro-irrigation systems boast several key components and features that make them a sophisticated and eco-friendly approach to irrigation. Drip emitters, including various types like inline drip tubing, drip tape, and point-source emitters, strategically release water directly to the base of individual plants. The system relies on a network of durable tubing and pipes, resistant to clogging, to transport water from the source to the emitters. Filters and pressure regulators prevent clogging and ensure a consistent flow, optimizing performance. Control valves regulate water flow, and automation through timers and controllers allows for precise scheduling based on plant water requirements, weather conditions, and soil moisture levels. Soil moisture sensors enhance efficiency by providing real-time data for dynamic irrigation adjustments.

Kumar et al. (2009) implemented an integrated approach combining water harvesting with a gravity-fed micro-irrigation system to efficiently manage water resources in terraced lands for vegetable cultivation. Enhancing and sustaining productivity in hill agriculture within the North-West Himalayan Region (NWHR) presents a significant challenge due to the ecological fragility characterized by altitudinal, climatic, and topographical variations. This study aimed to explore the potential for water resources development and utilization in crop production through gravity-fed micro-irrigation, thereby improving water utilization in the terraced landscape of the NW Himalaya. Water was harvested from a distant ultra-low-discharge water source, directed to a lined tank, and integrated with a micro-irrigation system (MIS) designed to operate by gravity. The system demonstrated satisfactory performance, with flow rate variation, Christiansen uniformity coefficient, and distribution uniformity recorded at 26.5%, 86.3%, and 87.5%, respectively. In comparison with check basin irrigation, the system achieved water savings of 41.1% and 33.3% for vegetable pea and French bean, respectively. Moreover, the water use efficiency of the system surpassed that of check basin irrigation. Economic indicators, including net present value, benefit-cost ratio, internal rate of return, and payback period, were employed to evaluate the gravity-fed MIS, resulting in values of INR 160,523 (1$ = 40.50 INR), 1.78, 12.2%, and 3.38 years, respectively. The integration of the gravity-fed MIS with water harvesting is recommended for effective and economical water utilization in vegetable cultivation on terraced lands within hill farming systems.

The satisfaction of farmers with drip irrigation technology and the factors influencing it, utilizing the European Satisfaction Model (ESM), has been examined by Rouzaneh et al. (2021). A cross-sectional survey, conducted on paper, involved 174 farmers in the Behbahan county of southwest Iran. The analysis using ESM revealed that the perceived ‘hard’ quality had a positive influence on perceived value. Additionally, the study found that perceived value, perceived image, and both ‘hard’ and ‘human’ quality had direct impacts on farmers' satisfaction. These four variables collectively accounted for 68% of the variance in farmers' satisfaction. Furthermore, loyalty was significantly and positively influenced by both satisfaction and perceived image. In light of these findings, recommendations were put forth to enhance farmers' satisfaction and, consequently, promote the wider adoption of drip irrigation among Iranian farmers.

Li, J., Zhang, Z. et al. (2019) conducted a study on the impact of micro-sprinkling with varying irrigation amounts on the grain yield and water use efficiency of winter wheat in the NCP (North China Plain), aiming to ensure wheat production and enhance water productivity in the region. To address these goals and reduce irrigation in the NCP, a two-year field experiment on winter wheat was carried out from 2016 to 2018. Micro-sprinkling irrigation, involving different irrigation amounts (60 mm, MI60; 90 mm, MI90; 120 mm, MI120; and 150 mm, MI150), was implemented, with the traditional local water-saving and productive flooding irrigation method (TI120) used as a control. The study focused on investigating grain yield (GY), dry matter accumulation (DM), root system distribution, and water utilization. The results revealed that the GY of MI60 decreased by 5.1%–13.4% compared with TI120, MI90 showed comparable GY to TI120, while MI120 and MI150 exhibited significant increases. The higher GY in micro-sprinkling treatments was attributed to a significant increase in 1,000-grain weight (TGW), resulting from delayed senescence in flag leaves during grain filling and increased post-anthesis DM. Additionally, roots predominantly distributed in the 0–60 cm soil profile and micro-sprinkling ensured adequate soil water supply in these areas during critical growth stages. Furthermore, micro-sprinkling, with reduced irrigation treatments, significantly enhanced root system growth into deeper soil layers, improving moisture absorption and utilization. In comparison with TI120, the same irrigation amount treatment under micro-sprinkling (MI120) significantly increased water use efficiency (WUE) due to higher GY and lower seasonal evapotranspiration (ET). MI150 increased WUE due to higher GY and comparable ET, MI90 achieved similar WUE to TI120, and MI60 exhibited similar or lower WUE compared with TI120. In summary, a judicious reduction of irrigation amount under micro-sprinkling (MI90) can ensure winter-wheat grain yield and efficient utilization of irrigation water in the NCP.

The combined approach of irrigation methods and fertilization rates to enhance the growth and water-fertilizer use efficiency of young mango trees has been explored by Li et al. (2021). In southwest China, improper irrigation and soil nutrient deficiencies adversely impact the normal physiology and growth of tropical fruit trees, particularly mango (Mangifera indica L.). In an effort to identify the optimal fertigation mode for mango trees, the study examined the effects of three micro-irrigation methods (micro-SI, drip irrigation (DI), and micro-moistening irrigation (MM)) on various parameters such as photosynthetic characteristics, hydraulic conductivity, growth, and water-fertilizer use efficiency of young mango trees. This investigation encompassed four fertilization rates (0 g plant⁻¹ (FN), 9.3 g plant⁻¹ (FL), 18.6 g plant⁻¹ (FM), and 27.9 g plant⁻¹ (FH), using a compound water-soluble fertilizer) within a randomized block design experiment. The findings revealed that DI and MM increased the net photosynthetic rate (Pn) by 17.50% and 28.95%, root hydraulic conductivity (Kr) by 39.65% and 52.69%, shoot hydraulic conductivity (Ksh) by 48.63% and 82.38%, total dry mass (DM) by 27.44% and 47.13%, water use efficiency (WUEET) by 43.27% and 73.17%, fertilizer agronomic efficiency (FAE) by 45.92% and 95.41%, and partial factor productivity of fertilizer (PFP) by 33.96% and 54.44%. However, they reduced transpiration rate (Tr) by 6.61% and 16.38%, leaf with petiole hydraulic conductivity (Kl + p) by 13.11% and 30.32%, and water consumption (ET) by 10.38% and 14.85% compared with SI. Increasing the fertilization rate significantly enhanced Pn, Tr, total hydraulic conductivity (root to leaf), total DM, healthy index (Hi), and WUEET. The maximum values were observed in the FM condition. FAE showed an initial increase followed by a decrease, while PFP gradually reduced with the rising fertilization rate. The MMFM condition (MM irrigation with a moderate fertilization rate of 18.6 g plant⁻¹) exhibited the highest total DM and WUEET, surpassing SIFN (CK) by 2.32 and 2.58 times, along with the largest FAE of 4.95 kg⁻¹. Consequently, MMFM emerged as the optimal coupling mode of irrigation method and fertilization rate, significantly promoting the growth, and improving the water-fertilizer use efficiency of young mango trees.

Previous studies have offered valuable insights into sustainable agricultural practices, water management, and crop productivity enhancement. The results indicate that the most effective approach involves MM irrigation coupled with a moderate fertilization rate, fostering growth, and enhancing the efficiency of water and fertilizer use. Together, these studies present valuable insights for researchers, policymakers, and practitioners seeking to tackle water scarcity, elevate agricultural productivity, and advocate for sustainable farming techniques.

Micro-irrigation's ability to conserve water is a standout feature, not only delivering water directly to the root zone with minimal losses to evaporation or runoff, but also maximizing water use efficiency. The system can also incorporate fertigation, the simultaneous application of water and fertilizers, ensuring targeted and efficient nutrient delivery for healthy plant growth. With versatility tailored to various crops, soil types, and topography, micro-irrigation systems find applications in orchards, vineyards, row crops, and greenhouses. Beyond operational benefits, these systems contribute to sustainable agriculture by minimizing water wastage, reducing soil erosion risks, and promoting responsible water resource use. In summary, micro-irrigation systems present a holistic solution for farmers, enabling them to optimize water use, boost crop yields, and adhere to sustainable agricultural practices.

Efficient water irrigation refers to the judicious and effective use of water resources in agricultural practices to achieve optimal crop growth while minimizing water wastage. The effectiveness of irrigation, as gauged by the amount of water needed to irrigate a field, farm, basin, irrigation district, or an entire watershed, is referred to as irrigation efficiency (Howell 2005). This term, crucial in engineering, requires a comprehensive grasp of soil and agronomic sciences to optimize the advantages derived from irrigation. A heightened comprehension of irrigation efficiency holds the potential to enhance the judicious utilization of limited and diminishing water resources, thereby contributing to the improvement of crop and food production in irrigated areas.

Efficient water irrigation practices are essential for addressing water scarcity challenges, promoting sustainable agriculture, and ensuring the responsible management of water resources. As global water concerns continue to grow, the adoption of these efficient irrigation methods becomes increasingly crucial for the long-term viability of agriculture.

Levidow et al. (2014) conducted a study on enhancing water-efficient irrigation, emphasizing the potential economic benefits and environmental alleviation associated with innovative irrigation practices. Extension services have played a role in disseminating essential knowledge to farmers, aiding in the adoption of viable solutions, and maximizing the advantages of irrigation technology. Despite investments in technological advancements often resulting in elevated water prices, the full potential benefits in terms of water efficiency have not been realized. Farmers frequently face challenges in obtaining information about crop water requirements, effective irrigation practices, and the yield response to various water management techniques, contributing to uncertainties in on-farm water efficiency. This is exemplified in two case studies where there is a notable need for improvement but a lack of a knowledge-sharing system to guide farmers and resource managers in identifying opportunities for enhancements.

The responsibility for efficient water management is sometimes deferred to speculative possibilities, such as additional supplies from treated wastewater reuse or prolonged periods of low water pricing. This displacement of responsibility, coupled with the assumption that farmers' irrigation practices already possess adequate water use efficiency, may hinder efforts to enhance efficiency. To address this, a continuous exchange of knowledge is imperative, allowing all relevant stakeholders to share responsibility throughout the entire water supply chain. With this collaborative approach, more water-efficient management could offer broader environmental advantages while providing economic incentives for farmers.

Cut-off irrigation as a viable strategy to enhance water use efficiency and improve the productivity, quality, and storability of select onion cultivars also has been introduced by Geries et al. (2021). The significance of water management has become a common theme in discussions surrounding high-yield farming and contemporary agricultural best practices. Conducted in the northern region of Egypt, specifically in Kafr El-Sheikh Governorate, a field experiment utilized four cut-off furrow irrigation treatments (100%, full irrigation – considered as a control; 90%, 80%, and 70% of strip length) to evaluate the impact of reduced water supply on onion (Allium cepa L.) production, considering three different cultivars (Giza red, Giza 20, and Behairy red). Employing a strip-plot design with three replicates over two consecutive seasons (2014–2015/2015–2016), the study revealed that, irrespective of onion type, the 80% water supply level resulted in higher marketable and total bulb yield (t/ha), along with improved quality traits and storability compared with other irrigation treatments. The observed interspecies differences were generally minimal, with significant variations mainly noted in Giza red and Behairy red for all examined characteristics, with the best results obtained under the 80% irrigation level. Aside from enhancing overall quality and harvestable yield, this treatment demonstrated favorable consumptive water use efficiency, water productivity, and significant water-saving benefits. While the maximum water saving occurred with the 70% irrigation treatment, it was accompanied by an economically unacceptable yield. In contrast, the traditional technique (100% water supply) consumed considerably more water, exceeding the most effective treatment (80%) by 1,195.77 cubic metres per hectare (equivalent to 11.96 cm in depth/height). In conclusion, the cut-off irrigation technique proves to be an efficient and effective intervention for increasing onion yields while preserving post-harvesting quality and achieving water savings. However, extending the scope of the study beyond onions is crucial to expanding the benefits to other crops and ensuring adequate water management under deficit irrigation conditions.

Abu-Awwad (1999) conducted a study investigating the impact of mulch and varying irrigation levels on soil evaporation, transpiration, evapotranspiration, and onion yield in a controlled glasshouse pot experiment conducted from December 1, 1996, to May 14, 1997. The experiment involved applying five different irrigation levels to both covered and open clay loam soil surfaces, each replicated four times. Daily measurements of water losses through evaporation and/or transpiration were taken by weighing, with irrigation water administered weekly. The quantity of irrigation water for each treatment was determined based on weight differences. Increasing irrigation water significantly elevated evapotranspiration and/or transpiration. The use of mulch led to a notable reduction in evapotranspiration, while transpiration increased significantly compared with treatments with open soil surfaces. Covering the soil surface resulted in a nearly 70% reduction in the required irrigation water for onion crops across all irrigation treatments compared with open soil surface treatments, as it eliminated wet soil surface evaporation. The increased water application raised the evaporation–transpiration ratio due to a greater amount of water available for evaporation. In the onion crop, the majority of irrigation water (approximately 1.7 times transpiration) was lost through evaporation. For both covered and open soil surface treatments, the measured potential transpiration depth was around 150 mm, in contrast to approximately 400 mm of evapotranspiration depth in the open soil surface treatment. Covered soil surface treatments exhibited significantly higher onion yields than open surface treatments at lower water levels, primarily due to substantial soil evaporation in the open soil surface conditions. However, as the total water applied increased, onion yields for open and covered soil surfaces became comparable. Maximum water use efficiency in the covered soil surface treatment was observed at the highest water level (W4 = 197 mm irrigation), whereas in the open soil surface treatment, the maximum water use efficiency occurred at the intermediate water level (W2 = 209 mm irrigation).

LEPA (low energy precision application) irrigation as a response to assess the yield and water use efficiency of corn (Zea mays L.) has been implemented by Howell et al. (1995). In the Southern High Plains, there is a notable expansion of centre-pivot sprinklers, and the utilization of LEPA application methods is widespread to mitigate water application losses, make use of relatively low well-yields, and decrease energy demands for pressurization. The research focused on evaluating the LEPA irrigation impact on corn grown in slowly permeable Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll). The field study, conducted during the 1992 and 1993 cropping seasons in Bushland, Texas, explored the effects of varying irrigation amounts. In 1992, characterized by a wetter-than-normal season, grain yields ranged from 0.6 to 1.2 kg/m². In 1993, a season with slightly less rain, grain yields varied from 0.4 to over 1.5 kg/m², corresponding to increasing irrigations from no-post plant irrigations to fully meeting crop water use. Full irrigation amounts ranged from 279 mm in the wet year to over 640 mm in the more normal year. A significant relationship was observed between grain yield and water use over the two years, expressed as GY (kg/m²) = 0.00169 (WU (mm) – 147), with an R² of 0.882 and an Sy/x of 0.10 kg/m². Deficit irrigation, even with LEPA, reduced yields by impacting seed mass and kernels per ear. Dry matter yield and grain yield exhibited a proportional relationship. LEPA irrigation demonstrated efficiency in allocating applied water to crop water use. For LEPA on the Pullman-type soils with furrow dike basins, irrigation amounts should not exceed 25 mm for alternate furrows (0.76 m rows).

The agriculture sector is currently grappling with the significant challenge of adopting innovative and efficient irrigation methods, as highlighted by Difallah et al. (2017). A linear programming model has been introduced to streamline water usage optimization. The core concept of this model involves assessing the efficiency or inefficiency of precipitation to ascertain the necessary irrigation water quantity for optimal water utilization. To implement this approach, the decisional structure of the ‘knapsack’ problem was employed, and the integration of linear programming with this form yielded satisfactory results. Field experiments were carried out in Algeria, and a model utilizing linear programming was developed based on calculated budgets. A comparison between the outcomes of the model and observation from the field indicates a potential 28.5% reduction in water consumption.

Li, J., Gao, Y. et al. (2019) conducted a thorough comparison of various irrigation strategies using saline water in tomato production, considering aspects such as soil properties, plant growth, fruit yield, and fruit quality. The increasing use of saline water in regions facing freshwater scarcity has become a common practice for crop cultivation. However, the continuous application of saline water often leads to detrimental effects on the soil–crop system. This study delved into the impact of different saline water irrigation strategies on soil properties, tomato plant growth, fruit yield, and fruit quality. The irrigation approaches encompassed continuous freshwater irrigation (FI), continuous saline water irrigation (SI), blending saline water with freshwater (BI), alternating irrigation with saline water and freshwater (AI), and irrigating with freshwater in early sensitive stages followed by saline water in later tolerant stages (CI). Overall, saline water irrigation negatively influenced the soil–crop system by elevating pH, electrical conductivity, salt ions (Na⁺, Cl⁻, and SO₄^2–) in soils, sodium adsorption ratio in soils, and Na+ content in plant tissues. Simultaneously, it reduced K + /Na+ in both soils and plant tissues, along with the relative growth rates of plant height and leaf area, plant biomass, and fruit yield (when comparing SI versus FI). However, the adverse effects were generally mitigated by the BI, AI, and CI treatments compared with the SI treatment. Although there was no significant difference in soil properties among the BI, AI, and CI treatments, the AI treatment consistently demonstrated higher fruit yield compared with the BI and CI treatments, even showing no significant difference compared with the FI treatment in two out of three cropping seasons. Furthermore, the AI treatment significantly enhanced the levels of vitamin C, soluble sugar, solids, glucose, fructose, and sucrose in tomato fruits compared with the FI treatment. These findings suggest that alternate irrigation (AI) proves more effective than blending (BI) and cycling (CI) irrigation in alleviating the detrimental effects of saline water on the soil–crop system.

The economic efficiency of irrigated agricultural enterprises using a non-radial data envelopment analysis approach was evaluated by Azad et al. (2015). In contrast to prior studies employing radial measures within data envelopment analysis to determine efficiency scores based on overall production technology, their approach involves the computation of non-radial measures. This method helps comprehend the efficiency of individual inputs utilized in the production process, allowing for the decomposition of economic efficiency into water use efficiency and managerial efficiency. This breakdown facilitates the derivation of an efficiency score specifically for water as an environmentally sensitive input in irrigated crop production systems, surpassing the traditional measurement of water use efficiency. The findings reveal that while the overall efficiency of the examined irrigated enterprises is notably high, water use efficiency scores are relatively low. This suggests that Australian irrigated farms exhibit superior efficiency in overall farm activity management but face challenges in effectively managing water resources, posing a threat to the industry's sustainability.

Notably, there is considerable variation in water use efficiency scores among irrigated enterprises and across regions. Analyzing these disparities can offer valuable insights for current policies and future initiatives aimed at enhancing water use efficiency, ultimately contributing to a more sustainable irrigation industry.

Clothier & Green (1994) conducted an analysis of root-zone processes and their role in optimizing the efficient use of irrigation water. The imperative for a more effective agricultural utilization of irrigation water stems from heightened competition for water resources and the escalating demand for environmentally conscious irrigation practices. This review, dedicated to the 25th Jubilee volume of Agricultural Water Management, focuses on three key root-zone processes influencing water use efficiency in irrigation. First, the discussion revolves around the contribution of macropores in facilitating the preferential transport of irrigation water to deeper layers during infiltration under both sprinkler and flood systems. Suggestions are made to achieve a more uniform entry of irrigation water into the root-zone by aligning the sprinkler rate with the soil's matrix hydraulic conductivity or by modifying the soil surface macro-porosity prior to flood irrigation. Second, the environmentally adverse leaching of chemicals during irrigation can be mitigated by initially washing applied fertilizer into dry soil with a small amount of water. This initial water pulse, drawn into the soil's microporosity through capillarity, carries dissolved fertilizer, making it resident and available for plant uptake while minimizing subsequent leaching risks. Concurrently, initially resident solutes in dry soil, such as salts, are more effectively displaced by infiltrating irrigation water. Lastly, observations through time domain reflectometry (TDR) of changing SWC in the kiwifruit vine's root-zone and direct measurements of sap flow within individual roots underscore that plants can rapidly adjust their spatial water uptake patterns in response to irrigation. The pivotal role of near-surface roots in water uptake is emphasized. Considering these three root-zone processes reinforces the proposition that more efficient and environmentally sustainable water management can be achieved through higher-frequency applications of smaller irrigation amounts.

An integrated approach aimed at enhancing water use efficiency (WUE) through a comprehensive understanding of the physiological mechanisms governing crop responses to water deficit was promoted by Kang et al. (2021). Water use efficiency, representing the ratio of plant carbon gain to water utilization across diverse spatiotemporal scales, encompasses intricate factors related to physiology, agronomy, engineering processes, and management practices. Addressing the global water scarcity challenge and ensuring food supply necessitates the improvement of WUE at different scales, involving an in-depth comprehension of crop physiological responses to water deficit and the innovation of field water management technologies. The review delves into the latest developments and future prospects in the research domain dedicated to enhancing WUE at various scales, highlighting key challenges and potential practical solutions. The proposed strategy revolves around a water-saving, quality-enhancing, and highly efficient water use approach, incorporating diverse advanced technologies to improve WUE.

This comprehensive management approach is based on an understanding of crop physiological responses to water deficit, crop water requirements throughout their life cycle, precision irrigation management informed by real-time crop response monitoring, and crop water-yield quality models. The review aims to serve as a valuable resource for researchers in water management communities, fostering the sustainable development of water-saving agriculture in regions facing water shortages.

Ma et al. (2020) conducted a study comparing the effectiveness of direct root-zone irrigation, a novel subsurface drip irrigation strategy focused on water conservation, with traditional SDI methods, to elucidate the potential advantages of direct root-zone irrigation. The two-year investigation assessed the performance of Vitis vinifera L. cv. Cabernet Sauvignon in a commercial vineyard situated in a semi-arid region of southcentral Washington State, USA, with loamy sand soil. The study examined plant water status, root characteristics, grape yield, berry attributes, and crop water use efficiency under three irrigation rates. Direct root-zone irrigation, when contrasted with SDI, demonstrated a 9%–12% improvement in grape yield and a 9%–11% enhancement in crop water use efficiency across varied climate conditions. The effects on berry composition were minor and potentially adjustable through irrigation rate modulation. Furthermore, grapevines subjected to direct root-zone irrigation exhibited a 48%–67% reduction in root number in the upper soil profile (0–60 cm) at high and moderate irrigation rates, accompanied by decreased water stress, as indicated by higher midday stem water potential. The primary factor influencing berry morphology was found to be irrigation rate, with reduced irrigation leading to decreases in berry weight, size, and quantity. Direct root-zone irrigation emerges as a promising tool for enhancing yield and crop water use efficiency, offering the potential for deep rooting to alleviate water stress in grapevines during seasonal droughts and the flexibility to modify berry morphology and composition by adjusting water usage.

Irrigation practices for rooftop greenhouses cultivating tomatoes in urban agriculture have also been optimized by Parada et al. (2021) . The increasing urban population underscores the importance of efficient urban agriculture (UA) concerning water and nutrient utilization. Addressing the irrigation needs of UA becomes crucial in urban areas where water resources are often scarce. This study aims to explore three fertigation management practices in a rooftop greenhouse for tomato cultivation in Barcelona: (1) open management (OP); (2) recirculation (RC), utilizing 30% of drained water for irrigation; and (3) the same recirculated management of RC with an additional 15% reduction in freshwater input (RR). Despite variations in water and nutrient inputs, all three practices yielded similar results: 16.2, 17.9, and 16.8 kg·m⁻² for OP, RC, and RR, respectively. In terms of water use efficiency, RR demonstrated the highest efficiency at 48.7 L kg⁻¹ of tomatoes, followed by RC (52.4 L kg⁻¹) and OP (75.2 L kg⁻¹). RR exhibited a 7% improvement in water use efficiency. Regarding environmental performance, RC showed superior results in most impact categories during the operational phase, particularly in marine and freshwater eutrophication, with 44% and 93% fewer impacts than OP due to nutrient recirculation and reduced nutrient leaching. Despite the additional equipment required, the recirculation management displayed better infrastructure performance in the range from 0.2% to 14% depending on the impact category. This study provides valuable insights for evaluating urban agricultural projects, encouraging sustainable practices aligned with UA's sustainability.

Wang et al. (2021) compared various irrigation methods to assess their impact on the yield and water use efficiency of jujube trees. The scarcity of water resources poses a challenge to jujube cultivation in southern Xinjiang, and the adoption of water-saving irrigation technologies is essential to address this issue. The study aimed to evaluate the response of irrigation water use efficiency, jujube yield, and quality to different irrigation technologies, specifically vertical tube irrigation at three water-pressure levels (0.8, 1.0, and 1.2 m) and SDI used as a control. Over a two-year field experiment, vertical tube irrigation demonstrated water savings ranging from 37% to 70%, with water use efficiency being 1.4–4.3 times higher than SDI. Hui–jujube trees irrigated through vertical tube irrigation exhibited slightly increased yield and reduced fruit cracking (25%–83%) compared with those irrigated with drip irrigation. Moreover, a significant improvement (P < 0.05) in the sugar–acid ratio was observed. The continuous water supply in vertical tube irrigation maintained a stable SWC in the main root layer (20–60 cm), creating an optimal soil–water–air environment for jujube growth. Vertical tube irrigation achieved water savings by delivering water directly to the main root layer through buried emitters, minimizing water evaporation from the upper soil layer. The irrigation water amount in vertical tube irrigation was proportional to the water supply pressure, with the highest water use efficiency observed at the lowest pressure (0.8 m). These findings provide a scientific foundation for implementing vertical tube irrigation in arid regions.

Zhang et al. (2021) investigated the effectiveness of continuous regulated deficit irrigation (CRDI) in enhancing water use efficiency (WUE) and drought resistance in peanuts. While RDI has proven valuable in improving peanut WUE for sustainable industry development, prior studies focused on single growth periods, limiting water-saving potential. This study, employing a split-plot design, applied three levels of water deficit treatment – severe (H1/J1, 45% field capacity), moderate (H2/J2, 55% field capacity), and mild (H3/J3, 65% field capacity) – during the flower-pegging (H) and pod-setting (J) stages. Moderate CRDI (H2J2) consistently enhanced the instantaneous WUE of peanut leaves. Yield did not significantly decrease under the H2J2 treatment, being only 4.47% lower than the H3J2 treatment, which had the highest yield. The highest WUE was observed in the H2J2 treatment (1.87 kg⋅m⁻³). Upon reaching the lower SWC limit during the pod-setting stage, the proline content in the H1J1 treatment was 13.57 times higher than H3J3, indicating substantial drought stress. In the second instance, the proline content in H1J1 was 7.14 times higher than H3J3, demonstrating improved peanut drought-resistance due to the drought-rehydration exercise at the flower-pegging stage and alleviation of drought stress in the pod-setting stage. The study concludes that moderate CRDI is beneficial for enhancing peanut drought-resistance in arid and semi-arid areas while significantly promoting higher WUE.

Efficient utilization of irrigation water has become a paramount concern in agricultural production due to the rising global population and depleting water resources. This is in line with Nair et al. (2013) in their review on comprehensive examination of the effectiveness of irrigation water use, considering various disciplinary perspectives. The significance of irrigation water efficiency is further underscored by apprehensions about climate change, which may result in a more arid climate in the future. Despite being a widely used term among plant physiologists, agronomists, irrigation engineers, and economists, the definition and interpretations of irrigation efficiency vary across different disciplines. This review has presented and compared irrigation water use efficiency through the lenses of various disciplines, facilitating a mutual understanding among researchers from different fields and promoting multidisciplinary thinking and research.

The lesson learned from these previous studies is that efficient water irrigation relies on a multifaceted approach encompassing various key strategies. Smart irrigation systems stand at the forefront, incorporating cutting-edge technologies such as sensors, data analytics, and automation. These systems enable the precise monitoring and control of irrigation processes in real-time, ensuring crops receive the optimal amount of water precisely when needed. Drip and micro-irrigation systems play a pivotal role by delivering water directly to the root zone, minimizing losses to evapotranspiration and runoff. Micro-irrigation components, including drip emitters and efficient tubing, further contribute to water conservation and the targeted application of water resources. Soil moisture monitoring utilizes sensors to regularly assess soil moisture levels, facilitating the customization of irrigation schedules based on the actual water requirements of crops, thereby preventing over-irrigation.

Weather-based irrigation integrates weather data into management systems, allowing for dynamic adjustments to irrigation schedules based on anticipated precipitation. Water-saving technologies, such as soil moisture retention practices, rainwater harvesting, and the cultivation of drought-resistant crops, enhance water use efficiency across diverse agricultural contexts. Precision agriculture involves the adoption of precision farming techniques, ensuring the precise application of water, fertilizers, and other inputs tailored to the specific needs of distinct areas within a field. This targeted approach minimizes waste and maximizes the efficient utilization of resources. Education and training form a crucial component by providing farmers with insights into best practices in irrigation, water conservation, and the effective utilization of modern irrigation technologies. This knowledge empowers farmers to make informed decisions, ultimately optimizing water usage and contributing to sustainable agricultural practices.

In Indonesia, irrigation technology is crucial for agricultural productivity, especially for smallholder farmers who form the bulk of the farming community. Despite advancements in irrigation technology, the adoption rate among these farmers remains low due to a combination of socio-economic, technical, and environmental challenges. Traditional irrigation methods, such as surface irrigation through canals and rivers, continue to dominate, while modern technologies like drip irrigation, sprinkler systems, and smart irrigation remain underutilized (Bukchin & Kerret 2020). These modern systems, though more efficient, face barriers to adoption, primarily due to their high initial cost and the limited access smallholder farmers have to credit and financing. Many of these farmers operate on small landholdings, which limits the economic viability of investing in modern irrigation systems that are better suited to larger-scale operations.

Another major challenge is the limited technical knowledge and training available to smallholder farmers. Operating modern irrigation systems requires skills that many farmers lack, and without adequate support or training programs, the complexity of these systems becomes a significant hurdle. Institutional and policy barriers also play a role, with government initiatives often focusing on large-scale irrigation infrastructure rather than tailored solutions for smallholder needs. Bureaucratic delays in accessing subsidies and other forms of support further impede adoption. Additionally, water access is a persistent issue, exacerbated by climate change (Arifah et al. 2022; Purwanti et al. 2022). Irregular rainfall and prolonged dry seasons, particularly in eastern Indonesia, reduce the availability of water resources, making even the most advanced irrigation systems less effective (Rejekiningrum et al. 2022).

Social and cultural factors also influence adoption rates. Farmers are often hesitant to adopt new technologies unless they see successful implementation in neighboring farms (Tiemann & Douxchamps 2023). In regions like Bali, where traditional irrigation systems such as the Subak are deeply embedded in local culture, there is resistance to more modern, individualized irrigation methods. Despite these challenges, efforts are being made to address them. The Indonesian government has introduced programs such as the Irrigation Acceleration Program and supports community-based water-user associations. However, these efforts need to be strengthened with expanded training programs, better financial mechanisms like microcredit for smallholders, and localized water management technologies, such as solar-powered pumps and rainwater harvesting systems, that are more suited to the needs of smallholder farmers. Encouraging peer learning through demonstration plots and farmer-led workshops could also help overcome skepticism and build trust in modern irrigation technologies (Djufry et al. 2022).

The adoption of irrigation technology by smallholder farmers in Indonesia, particularly in regions like East Java and Aceh, is of great importance for improving agricultural productivity and adapting to climate change (Agussabti et al. 2022; Wijayanto et al. 2022). However, despite its potential benefits, widespread adoption has been hindered by a variety of socio-economic and infrastructural challenges.

In the context of cassava farmers in East Java, as discussed in the study by Muhaimin et al. (2020), the adoption of new technologies, including improved crop varieties, was shown to enhance agricultural income and household food security. However, the study also found that this adoption process can be uneven and may negatively impact the food insecurity management strategies of smallholder farmers. This suggests that while technology adoption can increase productivity, it might not necessarily be aligned with traditional risk-management practices. For these farmers, adopting new technologies might mean stepping out of their comfort zone, where traditional farming methods have long served as a safety net, albeit with lower productivity. The challenges here stem from a combination of factors, including limited financial capacity, lack of access to technology, and the uncertainty of adopting unfamiliar methods, especially in regions susceptible to climate variability and market fluctuations.

Smart farming technology (SFT) offers a modern solution to these challenges, yet the transition from conventional farming to SFT, as explored by Agussabti et al. (2022), remains slow, particularly for smallholder farmers in Aceh. One of the key challenges highlighted is the lack of readiness among farmers, primarily due to limited technical capacity and economic constraints. Although the farmers and extension workers exhibited a positive perception toward SFT, the significant investment required for smart devices and the technical expertise to operate them posed barriers. The divide between extension workers, who are more prepared to embrace SFT, and the farmers, who often struggle to afford and understand such technologies, highlights the need for targeted support. These findings underscore the necessity for capacity-building programs and subsidies to lower the cost of technology adoption, thereby helping farmers overcome the economic and educational barriers to smart farming.

In rice farming, technology adoption faces additional challenges in the form of environmental factors. As seen in the study by Connor et al. (2021), the adoption of sustainable farming technologies in Central Java has been met with various obstacles, including time constraints and the unsuitability of technologies to local field conditions. Farmers in riparian wetlands in Indonesia, for example, face unpredictable flooding and drought, which make it difficult to adopt and consistently apply modern irrigation systems. Lakitan et al. (2018) describe how farmers in South Sumatra, who manage land prone to both drought and flooding, require affordable and relevant technologies to improve water management. However, government intervention is necessary to build infrastructure such as polder systems to regulate water levels and make the land more arable. Without such support, smallholder farmers are left with few options for improving their water management, hindering their ability to adopt new technologies.

The study by Dewi et al. (2022) in North Aceh further demonstrates how environmental stressors such as salinity severely limit the ability of farmers to adopt improved farming techniques. In this case, salinity not only reduced the arable land but also decreased the productivity and income of farmers. Farmers responded to this challenge by either abandoning their land or, in some cases, improving irrigation systems to counter salinity. However, those who chose to invest in irrigation infrastructure often faced financial burdens that limited the extent of their improvements, indicating that technological adoption is heavily influenced by the economic capacities of individual farmers.

The combination of environmental challenges and limited access to capital is a recurring theme across smallholder farming systems in Indonesia. The study on climate change adaptation by Purwanti et al. (2022) found that participation in farmers' groups and access to agricultural-related infrastructure were significant factors in increasing the capacity of potato farmers in East Java to adapt to changing climate conditions. However, for many smallholder farmers, accessing such infrastructure and technologies is challenging, especially in more isolated regions. Infrastructure, particularly irrigation, plays a crucial role in resilience to water scarcity, as indicated by Aguilar et al. (2022), who showed that irrigation infrastructure and direct access to water sources were strongly associated with resilience to water scarcity in South Sulawesi.

Ultimately, the current state of irrigation technology adoption in Indonesia is marked by an uneven distribution of resources, knowledge, and readiness among smallholder farmers. While there are numerous success stories of technological adoption improving productivity and income, significant barriers remain. These include environmental challenges such as water scarcity and salinity, economic constraints like the high cost of technology, and social factors such as the low capacity of farmers to absorb and implement new methods. Overcoming these challenges will require concerted efforts from both the government and private sector to provide infrastructure, financial support, and education, ensuring that smallholder farmers have the necessary tools to adapt and thrive in an increasingly unpredictable agricultural environment.

Evapotranspiration (ET) is the combined process of water evaporation from the soil surface and transpiration from plants. Evapotranspirative irrigation systems aim to deliver water to crops based on their actual water needs, as influenced by environmental factors such as temperature, humidity, wind, and solar radiation. Evapotranspirative irrigation is categorized as a form of simple yet smart irrigation. Nevertheless, smallholder farmers have not embraced smart irrigation technology utilizing micro-controllers due to its elevated operational expenses. This research introduces strategies that design irrigation systems using uncomplicated automated technology based on the principle of evapotranspiration, aiming to alleviate the associated high costs.

Ardiansyah et al. (2019) conducted a theoretical study focused on enhancing water application efficiency in paddy field plots through the application of evaporative irrigation. The emphasis of this study is on the implementation of precision farming, which does not necessarily require sophisticated control technologies. Precision agriculture, guided by the principle of providing the right input at the right place, time, amount, and using the right tools, is the underlying concept. At the tertiary plot level, the provision of irrigation water for paddy fields has not been executed precisely. Typically, water allocation from tertiary canals is based on a planting plan, potentially leading to excessive water supply and reduced water productivity. The study's objective is to investigate the theoretical aspects of applying evaporative irrigation to paddy field plots and establish design principles for its implementation. The theoretical results indicate the need for a controller pipe to gauge water thickness in paddy field plots. The pipe controller manages the opening of the irrigation lid based on the float–ballast principle. The design principle involves simulating the reduction in the controller's water level, illustrating the decrease in water thickness in the plots. The tolerated water depth for paddy growth serves as the limit for providing irrigation water to the plots. The quantity of irrigation water supplied matches the plant's water needs during the ongoing paddy growth phase. An example of the controller-pipe water-level design for initiating and ceasing irrigation is set at 117.8 and 300 mm, respectively. The total water requirement for one crop season is calculated as 625 mm. With evaporative irrigation application, initial conditions of sufficient water eliminate the need for irrigation water until the 31st day. Subsequent irrigation water application until harvesting only requires 477 mm. This water provision aligns with the daily calculated plant water requirements (Ardiansyah et al. 2019).

Muharomah et al. (2021) and Muharomah et al. (2023) have formulated an evapotranspirative subsurface irrigation model, which underwent testing using water lettuce in Bogor, Indonesia. This form of automatic irrigation relies on the fundamental concept of plant response to evapotranspiration. Specifically designed as subsurface irrigation, this method is distinguished by its high efficiency. The irrigation system regulates water supply through a floating valve, which responds to the rate of water loss due to evaporation. Remarkably, this system operates without the need for electricity to adjust the floating valve, as it functions automatically based on a predetermined water level. The automatic floating valve is directly linked to the main water reservoir, facilitating water delivery to the pot through a connected-vessel principle. According to this principle, if a vessel is filled with a liquid, all connected vessels will maintain an equal water level. The evapotranspirative subsurface irrigation technology demonstrated effective functionality during the study. The automated irrigation system, utilizing a floating valve, appropriately distributed water throughout the planting period, ensuring consistent water levels. Moreover, the model effectively drained excess water volume from the planting pots caused by heavy rainfall. The model exhibited commendable performance in both physical and economic water productivity. Tested with water lettuce over three planting periods, the model yielded 2,516.1 g of biomass, with a total water consumption of 204.3 litres during the growth period. The irrigation water supplied amounted to 1.9 litres. The physical water productivity in this study was 12.32 g L⁻¹, irrigation water productivity reached 1,307.34 g L⁻¹, and economic water productivity was IDR 9.2/kg. Notably, the economic water productivity indicated potential cost savings of approximately IDR 22.7/kg in terms of irrigation water expenses for crop production.

Efficient water-saving irrigation is frequently hindered by the timing of water application, as supplying water based on predetermined time intervals may not align with the actual water needs of the plants. Therefore, considering water provision through irrigation based on the amount of evaporation that takes place becomes essential to meet the specific water requirements of the plants. Amalia et al. (2020) developed an evaporative irrigation system tailored for regions with low precipitation. The effectiveness of evaporative irrigation was examined in regulating the distribution of drip irrigation water. The experimental crop, specifically peppers, thrives in arid conditions, making the combination of evaporative and drip irrigation technologies well-suited to address the water requirements of these plants. The research spanned five months in a greenhouse, focusing on components of the water balance, including the evaporation rate determined by variations in the water level of the supply tank. Results indicated higher evapotranspiration levels outside the greenhouse compared with inside. In the initial stages of pepper cultivation, evapotranspiration inside and outside the greenhouse measured 5.2 and 4.9 mm/day, respectively. The average evapotranspiration during the observation period was 4.1 mm/day inside and 3.8 mm/day outside. The application of water through the evaporative irrigation system at 5.2 mm/day effectively met the evapotranspiration needs of peppers, which averaged 4.1 mm/day. This water supply stimulated primary branch growth and flowering, contributing to normal pepper-plant development with a calculated crop coefficient ranging from 0.1 to 0.7 (Amalia et al. 2020).

Evapotranspirative irrigation has undergone testing on peat soils in Indonesia, a country boasting an expansive 18 million hectares of peatland. Diansari et al. (2019) conducted a study to assess the productivity of water and floating pots, evaluating the effectiveness of using floating pots for agriculture in wetlands with evapotranspirative subsurface irrigation. This irrigation system involved seeping water from below into the planting medium through porous material. The experiment utilized five types of planting media, consisting of mineral soil mixtures, and varying percentages (0%, 30%, 50%, 70%, and 100%) of peat soil. Lettuce (Lactuca sativa) was chosen as the experimental crop. Over the 41-day planting period, the cumulative actual evapotranspiration was 40.56 mm, with a total water volume of 0.081 m³. Water productivity values for lettuce in planting media with 0% to 100% peat soil ranged from 1.37 to 0 kg/m³, while land productivity values ranged from 1.29 to 0 kg/m². Notably, the lettuce productivity in this study surpassed that of drip wet irrigation with limited water supply, which had a value of 0.61 kg/m³ (Contreras et al. 2008). The findings suggest that cultivating plants on floating pots with an evapotranspirative subsurface irrigation system could be an effective approach to optimize wetlands for agriculture, yielding higher water and land productivity compared with conventional methods.

The utilization of evapotranspirative irrigation technology is applicable for micro-irrigation within a greenhouse setting. Dewi et al. (2020) have introduced a straightforward controlled irrigation technology based on the evapotranspiration principle, designed for the easy cultivation of horticultural plants. This irrigation system operates on the fundamental principles of vessel connectivity and capillarity. As the evapotranspiration process occurs, the water content and level in the growing media decreases. The soil, serving as the growing media, absorbs water through the filter due to matric suction. An automated floating valve connected to the water reservoir releases water automatically when the water level falls below the set point, maintaining it at the reservoir's water level. The water level is set at the filter surface, ensuring that water input is distributed to the root zone based on the capillarity principle of the soil. The crop exhibited robust growth with no instances of plant mortality until the harvest period. The study's results revealed water productivity of 2.2 g L⁻¹ and land productivity of 1,038 g m⁻². The water consumption for cultivation with this system was 0.038 m³ or 38 mm. In comparison, the water consumption for kailan cultivation with SI in the greenhouse is 55 mm (Dewi et al. 2017). This highlights the ability of evapotranspirative irrigation technology to save 40% of water compared with SI when applied inside a greenhouse.

Evapotranspirative irrigation proves to be a beneficial irrigation technology for the mina-padi system in Indonesia (Arif et al. 2021). Paddy cultivation holds a significant place in Indonesian agriculture, particularly through the mina-padi system, combining rice farming with fish cultivation. However, this system is criticized for its perceived water wastage. Arif et al. (2021) proposed an evapotranspirative irrigation approach for the mina-padi system in Indonesia, aiming to conserve water by employing an irrigation floating-ball valve that adjusts water supply based on evaporation and evapotranspiration rates. The developed evapotranspirative irrigation system demonstrated effectiveness in mina-padi farming, as evidenced by low mean absolute errors across three water irrigation regimes: continuous flooded, wet, and dry. Through water balance analysis, it was observed that the dry regime required less water compared with the continuous flooded and wet regimes, with the lowest evapotranspiration rate ranging from 1.65 to 4.09 mm/day. This evapotranspirative irrigation system emerged as a crucial tool for managing evapotranspiration rates, contributing to enhanced land and water productivities while adapting to the impacts of climate change.

Important indicators to see and assess the economic factors of irrigation water are water productivity (Fuadi et al. 2016) and land productivity (Hasanah et al. 2015). Increasing productivity and irrigation water use efficiency in the application of irrigation technology can reduce irrigation water use per unit weight of agricultural produce (Sirait et al. 2015). Gains in water use efficiency can be achieved when water application is precisely matched to spatially and temporally distributed crop water requirements (Hassan-Esfahani et al. 2015). Water productivity of agricultural crops can also be improved by using smaller water supplies (Hasanah et al. 2017).

Nowadays, the most advanced evapotranspirative irrigation technology has been developed by Bogor Agricultural University (IPB) Indonesia, namely the Non-Powered Automatic Fertigator (FONi) as shown in Figure 1. FONi applies the concept of evapotranspiration irrigation that can meet the water needs of plants at any time without using electricity. FONi is a series of plant pots connected to a water supply tank and water level maintained to form a connected-vessel system. The nutrient solution can be put into a water tank to make fertilizer application more practical. This technology can increase irrigation efficiency by almost 100% and is registered under patent registration number P00202215852 in Indonesia.

FONi is related to the implementation of SDGs (Sustainable Development Goals) 3 (Good Health and Well-being), 9 (Infrastructure), 11 (Sustainable Cities), 12 (Sustainable Production and Consumption) and 13 (Climate Change Action) as well as Urban Farming and FAO Family Farming and IPB's efforts in fulfilling nutrition and maintaining family and community health. This technology introduces the non-powered fertigator, which is able to fulfil the needs of water and plant nutrients automatically without the use of electric power. This fertigator is a further development with a portable and knockdown structure.

FONi is a series of special pots, each of which is connected serially and in parallel and gets water/nutrient supply from a supply tank that is maintained by a water bulb-valve. The size of the pots depends on the type of vegetable or fruit plants to be cultivated. The flow of water from the water source to each plant is entirely driven by the suction of the plant roots in the process of actual evapotranspiration. Likewise, soil moisture can be maintained at a moisture content in the range of field capacity (pF 2.54).

FONi can be placed in any open field and crop house (Figure 2), either on the ground or a cemented platform, as long as it is accessible from the water source using a water pipe. Once the fertigator is installed, there is no need to manually apply water and fertilizer except to keep the plants free from pests and plant diseases. Therefore, users do not have to be farmers, but anyone can grow crops using this fertigator by referring to the manual.

This FONi invention presents a subsurface fertigation technology governed by the evapotranspiration mechanism. The concept behind this technology is driven by the recognition that effective utilization of irrigation water is crucial to address the unpredictable decline in water resources. The challenge lies in ensuring a water supply that aligns with crop evapotranspiration (ETc) while optimizing soil moisture. In this invention, an irrigation system is devised using technology that can deliver water directly to fulfil ETc without relying on electricity. The system comprises interconnected pots arranged in a series using water pipes at the base of the pots. The initial pot serves as a water-level regulator, and the concluding pot functions as a reservoir for drained water. Irrigation water is directed to pots with water levels below the preset threshold.

All features (parts) of this unpowered automatic fertigator technology for vegetable cultivation are assembled with a knockdown system, where all parts can be prepared separately, and then installed at the desired location (portable). The advantage of this technology is that it does not require a large area of land. The series of technologies can be adjusted to the available land area. This series of technologies can even be applied to roofs of buildings (rooftops).

The working principle of fertigation is controlled by the evapotranspiration mechanism. The basic concept of the fertigation mechanism is built on the simple principles of plant response to evapotranspiration. This unpowered automatic fertigator technology for vegetable cultivation controls the water supply using an automatic float valve based on the level of water loss due to evaporation that occurs. This technology does not require electricity to regulate the automatic float valve because it works automatically at a certain water level. The automatic float valve is directly connected to the connecting pipe from the tower/water reservoir to the fertigation inlet pot, then water is supplied to the fertigation inlet pot and forwarded to the planting pot through a water distribution pipe with the principle of a connected vessel. During the cultivation period, if there is water loss in the planting pot system due to evapotranspiration, the water input controlled by the automatic float valve will automatically flow to the fertigation inlet pot according to needs, namely based on the predetermined water level. The water level in the planting pot will follow the height of the fertigation inlet pot. The water discharge flowing from the fertigation inlet pot to the water distribution pipe will be read through the fertigation water meter, and can be opened or closed manually with the fertigation inlet stopper.

Vegetable cultivation is planted in polybag media that is inserted into the planting pot. The polybag contains approximately 12 litres of rice-husk planting media. The fertigation that flows into the planting pot will soak the polybag so that the plant roots will automatically get water through the subsurface. The water supplied through the subsurface will spread to the soil surface through the principle of capillarity.

This fertigation technology is controlled by evapotranspiration and rain. When it rains, the rainwater that falls will be collected in the planting-pot system. If the volume of rainwater exceeds the empty reservoir volume in the planting pot and has exceeded the infiltration capacity, rainwater will flow out of the planting pot as runoff. The height of the water that exceeds the water level set on the drainage outlet pot will flow through the drainage pipe as a drainage discharge. The height of this drainage pipe is also adjusted according to the height of the specified water set-point. The simplicity and smart design of the FONi system is what enables this irrigation technology to adapt effectively to the diverse challenges posed by climate change.

The performance of FONi has been investigated by Syafriyandi et al. (2023). This study examines the performance of FONi to supply water directly to the root zone and cease when a predetermined water level is reached through a water-level valve. The evaluation focuses on three vegetable types − water lettuces, choy-sum, and spinach − assessing land productivity, water productivity, and plant coefficients as indicators. The irrigation network comprises 12 potted plants, each measuring 33 cm in top diameter, 23.5 cm in bottom diameter, and 31 cm in height, with an additional pot of the same size serving as a water level controller. Automatic water flow initiates when water levels decrease in the individual plant pots, maintaining a set water level 10 cm below the soil surface. Results in land productivity for choy-sum, spinach, and water lettuce are 9.6, 3.6, and 25.1 kg m⁻², respectively. Water productivity values for choy-sum, spinach, and water lettuce are 29.0, 12.3, and 52.4 kg m⁻³, respectively. Crop coefficients range from 0.12 to 1.71 for choy-sum, 0.12 to 0.94 for spinach, and 0.16 to 1.46 for water lettuce. In conclusion, FONi technology is deemed highly effective, efficient, and easy to maintain and operate.

Muharomah et al. (2023), through the Tasikmalaya City empowerment project in vegetable cultivation using FONi, has identified high economic benefits, and the technology has proven to be adaptable to climate change. In the course of implementing FONi with horticultural crops in a field experiment, Kale was harvested after 14 days, and long beans were picked after 48 days. Over this 48-day period, the long-bean yield amounted to 3 kg, achieving land and water productivity of 2.9 kg m⁻² and 2.3 kg L⁻¹, respectively. Continuous CCTV monitoring indicated that long-bean harvesting extended for up to 60 days. The economic gains derived from cultivating long beans and kale in a single season exceeded construction and production costs. The FONi technology has the potential to achieve a highly attractive return-to-cost (R/C) ratio of up to 1.5, indicating substantial profitability. This means that for every Rupiah invested, there is a return of 1.5 Rupiahs, translating into a 50% profit margin. Such a promising R/C ratio highlights the strong economic viability of FONi, demonstrating that it generates 1.5 times the initial investment. In essence, the technology not only covers its costs but also yields a 50% return, making it a highly profitable and worthwhile investment for agricultural projects looking to maximize efficiency and returns. The substantial public interest, evident in a strong desire to adopt this method, implies its potential for widespread application. The ongoing implementation of this approach holds the promise of meeting future nutritional needs, ensuring a plentiful supply of safe and healthy vegetables for all residents. FONi, an advanced technology based on evapotranspirative irrigation, emerges as a solution for irrigation that is both effective and efficient, exhibiting high water productivity while adapting to climate change.

• 1. Research on irrigation technologies and water use efficiency has been conducted globally to harness the considerable potential for water conservation. Utilizing water-efficient technologies and practices alongside incentives for conservation and appropriate regulations, which restrict water allocation and use, is crucial. Identifying optimal, cost-effective irrigation management has the potential to address water scarcity effectively. The adoption of irrigation technology has the added benefit of improving water-efficient irrigation and can lead to significant water and energy savings.

• 2. Implementing smart irrigation as part of irrigation system management is a strategic approach worldwide. Smart irrigation systems can be developed to be cost-effective, efficient, and environmentally friendly. Designing automated water irrigation systems for urban farming can enhance water-saving irrigation scheduling and contribute to the development of efficient automatic irrigation systems. Similarly, the application of micro-irrigation systems in cultivated crops has the potential to substantially increase water productivity and significantly improve yield rates.

• 3. Evapotranspirative irrigation, a form of simple smart irrigation, has the potential to efficiently supply the right amount of irrigation water at the appropriate time. Despite its operational cost hindrance, smallholder farmers have not fully embraced smart irrigation technology that utilizes micro-controllers. This form of irrigation responds promptly to crop water loss through evapotranspiration, replacing water as needed based on predefined levels. FONi, an advanced technology based on evapotranspirative irrigation, provides more precisely measured irrigation water to plants that can further enhance water and economic productivity. In that less irrigation water evaporates less water, this irrigation system contributes to increased land and water productivities, making it adaptive to the impacts of climate change.

This study is part of the e-Asia Joint Research Program entitled ‘Development of Machine Learning and Remote Sensing-based Water Management Platform for Sustainable Agriculture in Asian Deltas’ (MARSWM-ASIA), and thanks are due to the IPB University for providing the additional research fund through the post-doctoral program in 2021.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.