Can water rights trading pilot policy ensure food security in China? Based on the difference-in-differences method

Food security is an important foundation for China's economic development and social stability, as well as a basis for stabilizing global food patterns (He et al., 2019; Liu et al., 2020). According to the Food and Agriculture Organization of the United Nations (FAO), food security is defined as ‘the availability at all times of material and economic access to adequate, safe and nutritious food to meet their dietary needs and food choices for an active and healthy life’. To ensure food security, the United Nations' Sustainable Development Goals (SDGs) stated aims to eliminate global hunger and achieve food security. The Chinese government attaches great importance to maintaining and boosting its domestic food security. Its ‘Central Document No. 1’ of the Communist Party of China (CPC) Central Committee provided guidance on food security from 2012 to 2020. More importantly, the document ‘China's food security’ in 2019 proposed the implementation of an in-depth national food security strategy. However, food security in China has faced a series of problems such as demand increases (Zhang et al., 2016; Liu et al., 2019), arable land reductions or degradation (He et al., 2019), and water shortages (Dinar et al., 2019; Lan et al., 2021).

Because water is the most basic input element in the food production system, effective management and distribution of water resources are essential to ensure food security in various regions (Li et al., 2010).¹ As a large agricultural country, China's agricultural water consumption accounts for about 62% of total water used.² Popularizing water-saving irrigation technology and improving agricultural water use efficiency are key steps to promote the intensive use of water resources, save agricultural water, and ensure the stable development of agriculture (Fei et al., 2021). From 2015 to 2020, the government's ‘Central Document No. 1’ put forward the implementation of national agricultural water-saving actions, acceleration of completion of water-saving renovation facilities in large- and medium-sized irrigated areas, and increase of agricultural water-saving efforts. Among them, the ‘Central Document No. 1’ for 2016, 2017, and 2019, respectively, explicitly pointed out that reform of comprehensive agricultural water pricing should be steadily promoted, agricultural water pricing should be reasonably determined, the mechanism of water-saving incentives and targeted subsidies should be established, and agricultural water use efficiency should be improved. The Ministry of Water Resources of PRC selected Henan, Ningxia, Jiangxi, Hubei, Inner Mongolia, Gansu, and Guangdong as pilot provinces (municipalities) in 2014 and began to implement a water rights trading pilot policy (WRTPP) in these provinces (municipalities).³ This policy uses the economic benefits from water rights trading⁴ as the main incentive for farmers to reduce their water consumption, establishing a water rights trading system, a water price system, and a water-saving incentive system as measures to promote the transformation of agricultural water use into a conservation-oriented way (Bigelow & Zhang, 2018).

Existing studies have shown that water rights trading can promote water redistribution (Wang, 2012). It can also improve the economic efficiency of agricultural irrigation water and help guarantee food security in countries with water shortage (Gohar & Ward, 2010). However, some studies showed that due to the high implementation cost, farmers' profits from water rights transactions are limited (Sun et al., 2016). In addition, higher water rights trading prices may cause farmers to switch to higher-value cash crops (Danso et al., 2021). Although this can increase farmers' incomes, it has a negative impact on helping ensure food security. Thus, the question of how the WRTPP affects food security remains open, along with the question of whether reducing water use in agriculture will have a negative impact on ensuring food security. Therefore, it is important to evaluate how the WRTPP can improve agricultural water-saving irrigation technology and help ensure food security.

The WRTPP mainly affects China's aim to ensure food security in the following ways. First, by raising the water price and establishing water-saving incentive mechanisms, the policy encourages farmers to improve the irrigation system and replace the traditional irrigation method with effective water-saving irrigation technology, which can help ensure sufficient water supply for the cultivating grains and increasing grain output (Yoo et al., 2013; Deng et al., 2020). Second, the WRTPP, which formulates effective agricultural water allocation guidelines and promotes optimal allocation of water resources, can improve agricultural water use efficiency to help guarantee food security (Misra, 2014; Wang et al., 2017).⁵ Third, the WRTPP adjusts agricultural irrigation water prices, which raises the cost of using agricultural water and increases the risks of planting cash crops. In order to reduce costs and avoid risks, farmers would then tend to plant fewer high-water-consuming crops and plant more food crops with low water consumption (Berbel & Gómez-Limón, 2000; Doppler et al., 2002), which can increase grain yield.

For this reason, this research attempts to determine whether the WRTPP will have a positive impact on helping ensure food security. If so, will food security be ensured by improving agricultural water-saving irrigation technology? Based on the data of 29 provinces (municipalities) in China from 2009 to 2018, this study uses a difference-in-differences (DID) model to examine the effects of WRTPP on helping ensure food security, which is measured by total grain yield, grain yield per area, and grain yield per capita. The empirical results show that: firstly, compared with the non-pilot provinces (municipalities), the WRTPP is conducive to helping ensure food security in the pilot provinces (municipalities). Specifically, the pilot policy has improved the total grain yield, grain yield per unit area, and grain yield per capita in the pilot provinces (municipalities). It has significantly increased the total grain yield and yield per unit area of rice, wheat, and corn. Secondly, after discussing the mechanism, it is found that the WRTPP can encourage farmers to adopt agricultural water-saving irrigation technology, which can improve irrigation water efficiency and increase the total grain yield and grain yield per unit area. Finally, further analysis shows that the WRTPP has a dynamic effect on the promotion of total grain yield and grain yield per unit area. This positive effect begins to increase after the third year of policy implementation, and reaches the maximum in the fourth year of policy implementation. Therefore, the WRTPP will help ensure food security for a long time.

This paper mainly has the following three important contributions. Firstly, it confirms the promoting effect of the WRTPP on grain yield, thus complementing the existing theoretical basis for studies on the influencing factors of helping ensure food security (Abebaw et al., 2020; Kansiime et al., 2021). Currently, in the relevant literature on the relationship between water rights policies and ensuring food security, more attention is paid to water price reform (Aidam, 2015), water rights trading (Xu et al., 2020), or other single systems on food production. Little attention is paid to the impact of the WRTPP on helping ensure food security from an overarching perspective. Secondly, from the perspective of agricultural water-saving irrigation technology, the paper studies the influence mechanism of the policy on food security. The findings indicate that facing increased water costs, farmers will actively adopt water-saving irrigation techniques to increase grain yields. The evidence can not only provide a comprehensive analysis of how the policy affects food yields but also help to clarify the key role of water-saving irrigation technology in contributing to helping ensure food security. Thirdly, we use the DID method to evaluate the net effect of the policy on food security. We took the provinces (municipalities) implementing the policy as the experimental group to construct a double difference at the regional and temporal levels, which overcame the estimation bias existing in previous studies.

Some prior studies have focused on the impact of water rights reform on food production. Optimizing the allocation of irrigation water resources through water rights reform has been found to be an effective way to improve grain production efficiency and realize food security (Li & Guo, 2014). Existing studies have focused on the positive impact of water rights on food production (Gohar & Ward, 2010). The study found that confirming water rights can reduce the competition for water and ensure the grain yield (Theesfeld, 2018). However, some studies have shown that water rights reforms have led to low-income small farmers becoming unwilling to adopt advanced irrigation technology or increase grain planting area, which has a negative impact on grain production (Mamitimin et al., 2015).

Some studies focused on the effect of water-saving irrigation technology on grain production. In terms of the impact of water-saving technology on food security, many studies concentrate on water-saving facilities construction, water-saving subsidies, and water-saving technology adoption. Their research results show that water-saving technology can effectively alleviate water resource constraints on agricultural production to improve agricultural economic benefits and stabilize grain yield (Berbel & Mateos, 2014). Especially in China, which has a serious agricultural water shortage, promoting water-saving technology through incentive mechanisms is conducive to resolving the water shortage crisis and promoting food security (Feike & Henseler, 2017).

Other studies have confirmed the roles of climate change, government intervention and many other factors in promoting or inhibiting food security. No unified conclusion has been reached regarding the impact of climate change on helping ensure food security. Some studies suggest that climate change has significant negative effects on food availability and stability (Bocchiola et al., 2019). Other studies suggest that climate change improves agricultural production conditions and thus positively impacts crop yields (Shi et al., 2014). Moreover, the conclusion of the impact of government intervention on helping ensure food security is also not unified. Some studies prove that government agricultural intervention policies, such as subsidies, will be conducive to helping ensure food security (Nhantumbo et al., 2016). However, other studies have shown that government interventions have limited impacts on ensuring food security (Lunduka et al., 2013).

To sum up, existing studies have focused on food security from different aspects, but there is still a lack of research on the impact of the WRTPP on helping ensure food security. Because this policy is an effective tool to promote the adoption of agricultural water-saving irrigation technology and reducing water conflict between industry and agriculture, it is necessary to explore its impact on agricultural production, especially on helping ensure food security. In addition, few studies have analyzed the impact of water rights reform on helping ensure food security from the perspective of improving agricultural water-saving irrigation technology. Based on this, we will comprehensively evaluate the impact and mechanism of the WRTPP on helping ensure food security.

Water rights and the corresponding trading market can help address water shortages by establishing tradable permits for water resources (Delorit et al., 2019). Rational water rights distribution is conducive to coping with the pressures caused by uneven water resources distribution, e.g., helping farmers who need more water to obtain sufficient supplies to ensure effective irrigation of land and thus improve agricultural incomes (Bekchanov et al., 2015). As a policy to adjust the water resources allocation and promote the adoption of water-saving irrigation technology, the WRTPP will help ensure food security in the following ways.

First, the WRTPP can promote increased uptake of agricultural water-saving irrigation technology. Under the dual pressure of industrial water crowding and limited agricultural water rights allocation, farmers will have greater incentive to improve their water-saving irrigation technology, thus increasing irrigation efficiency (Fang & Zhang, 2020). Furthermore, the WRTPP provides water-saving subsidies while establishing a water market and adjusting water prices, which encourage farmers to invest in irrigation systems and adopt water-saving technology (Gao et al., 2014; Kahil et al., 2015). Water-saving technologies such as drip irrigation and sprinkler irrigation can improve the water absorption rate of crops and meet the water demand for the growth of food crops to increase crop yields (Brinegar & Ward, 2009; Deng et al., 2020), thus helping ensure food security. In addition, studies have shown that when cotton fields are completely converted to grow wheat, the promotion effect of drip irrigation technology on food yield plays the largest role, so the promotion effect of water-saving technology on food security varies with different crop plantation structures (Lee & Jung, 2018).

Secondly, by adjusting agricultural water prices, the WRTPP can improve agricultural water use efficiency, which will then help ensure food security. The policy adjusts the agricultural water price and increase the irrigation cost. Water pricing is an effective management means to promote the efficient allocation of agricultural water, which can improve the production efficiency of agricultural water and help ensure food security⁶ (Gohar & Ward, 2010; Wang et al., 2017). Because rational irrigation is one of the effective measures to increase grain yield, the policy improves agricultural water efficiency, and alleviates the pressure of water shortage to ensure grain yield by means of water resources integrated management (Kang et al., 2017; He et al., 2019).

Finally, the WRTPP can help ensure food security through adjusting the plantation structure. Existing studies have confirmed that water price reform increases the opportunity cost of agricultural irrigation, which makes farmers plant more food crops with low water consumption instead of cash crops with high water consumption, a change in behavior that helps ensure food security (Berbel & Gómez-Limón, 2000; Ørum et al., 2010).⁷ For example, Doppler et al. (2002) took Jordan as an example to prove that the water rights allocation system could help farmers obtain greater economic benefits from agricultural production through the adjustment of plantation structure and water allocation strategy, but a rise of water price would increase the investment risk of farmers and reduce the planting of fruits, vegetables, and other crops with high economic value added. Based on the above analysis, the following hypothesis is proposed:

• Hypothesis 1: Water rights trading pilot policy can support food security.

• Hypothesis 2: Water rights trading pilot policy can help guarantee food security by improving the adoption of water-saving irrigation technology.

Our research objects are 29 provinces (municipalities) in China from 2009 to 2018. The 2013 Central Economic Work Conference proposed to achieve basic self-sufficiency in cereals and absolute safety in rations. It can be seen that rice, wheat, and corn, as the three main grains, are of great significance to ensure food security. According to the ‘China Rural Statistical Yearbook’ over the years, Hainan Province's rice yield accounts for less than 1% of the country's total yield and its wheat yield and corn yield have been zero since 2013. The yield of rice in Qinghai Province is zero and the total yield of wheat and corn accounts for about 0.14% of the total yield in the whole country. Therefore, in order to make the estimation results accuracy, we exclude Hainan Province and Qinghai Province and finally use panel data from 29 provinces (municipalities) in China to obtain 285 actual observations. In order to effectively analyze the impact and mechanism of the WRTPP on helping ensure food security, the data in this article comes from the ‘China Statistical Yearbook’, ‘China Rural Statistical Yearbook’, ‘Agricultural Statistical Yearbook’, and Chinese National Bureau of Statistics.

FAO measures food security from four dimensions, namely availability, accessibility, utilization, and stability. Using these indicators can accurately measure the food security. However, we cannot get the data at the provincial level in China. Additionally, stabilizing grain yield is still the key to ensuring China's food security.⁸ Existing studies also show that crops yield is very important to ensure food security (Parker et al., 2020). The long-term low level of food production will threaten global food security (Ray et al., 2015). Furthermore, the Food Security Index of FAO includes the average value of food production in the dimensions of availability.

Therefore, we select food security as the explained variable, which is measured by total grain yield, grain yield per unit area, and grain yield per capita (Ali et al., 2018; Liu et al., 2021). According to the China Rural Statistics Yearbook in 2019, the yield of rice, wheat, and corn accounted for 34.77, 21.55, and 42.16% of China's total grain yield, respectively, and other food crops only accounted for 1.52% of the total grain yield. Therefore, we select the total yield and yield per unit area of these three main grains to further analyze the impact of WRTPP on helping ensure food security.

WRTPP is the explanatory variable of this study. If the province (municipality) i belongs to the pilot area in year t, the value is 1; otherwise, the value is 0. Specifically, the Ministry of Water Resources issued the ‘Notice of the Ministry of Water Resources on the Implementation of Water Rights Pilot Work’ in 2014, proposing to launch water rights pilot projects in seven provinces (municipalities), including Ningxia, Jiangxi, Hubei, Inner Mongolia, Henan, Gansu, and Guangdong. Based on this, we select seven pilot provinces (municipalities) as the experimental group, and the remaining provinces (municipalities) as the control group.

Based on previous research (Liu et al., 2021), in the analysis, we control the characteristic variables of provinces (municipalities), including infrastructure construction, industrial structure, disaster degree, effective irrigation rate, pesticide input, machinery input, labor input, fixed asset input, time, and province fixed effects. Table 1 provides the variables' definitions.

The DID method has been widely applied in econometrics (Ashenfelter & Card, 1985; Girma & Görg, 2007; Wang et al., 2021). Recently, there are also studies that apply the DID method to evaluate the implementation effect of environmental policies (Elrod & Malik, 2017; Gehrsitz, 2017). For example, Mori-Clement (2019) combines the DID method with matching techniques to identify the effect of CDM investments on development and poverty. However, few studies have applied the method to evaluate the implementation effect of the WRTPP. Therefore, this paper uses the DID method to analyze the net effect of the pilot policy on helping ensure food security.

Among them, i represents province (municipality) and t represents year. Y_it represents the food security of province (municipality) i in year t. We use total grain yield, grain yield per unit area, and grain yield per capita to measure food security. Treat_it indicates whether the province (municipality) i belongs to the pilot province (municipality) in year t. Treat_it=1 means that province (municipality) i is a pilot province (municipality) in year t. Otherwise, Treat_it=0. X_it represents the control variables at the provincial level. μ_t represents the time fixed effect. λ_i represents the province fixed effect. ε_it is the random perturbation term. In formula (1), the coefficient of interest in this paper is β₁. If the estimated value of β₁ is greater than 0, it means that compared with non-pilot provinces (municipalities), the policy helps guarantee food security in the pilot provinces (municipalities). Table 2 reports the summary statistics for all variables.

Table 3 reveals the main conclusions of this study, using the DID method to analyze the impact of WRTPP on helping ensure food security. Column (1) of Table 3 examines the impact of the policy on total grain yield. The results show that the coefficient sign of the DID method estimator Treat is positive and significant at the 1% level, indicating that after controlling other influencing factors, compared with non-pilot provinces (municipalities), the policy improves total grain yield in the pilot provinces (municipalities) increased by 6.8 percentage points. This initially supports our hypothesis 1. Columns (3) and (5) further report the results of the policy on the grain yield per unit area and the grain yield per capita, respectively. The results present that the coefficients of the estimator Treat were significantly positive at the 5 and 1% levels, respectively, indicating that the results in Table 3 have sufficient accuracy and stability. Hypothesis 1 has been further verified. Moreover, these findings are comparable with the existing literature. Goetz et al. (2017) revealed that the water rights allocation agreement can effectively alleviate the drought constraints on food production. The results in columns (2) and (4) are significantly positive at the 1 and 5% levels, respectively, indicating that the policy implementation has increased total grain yield and grain yield per unit area of three main grains in the pilot provinces (municipalities), respectively, 11.1 and 3%. Therefore, the study indicates that the WRTPP can indeed help guarantee food security.

It is worth mentioning that the coefficients of other variables in Table 3 also have important economic significance. The higher the proportion of the secondary and tertiary industries in the industrial structure, the less the food security can be guaranteed. The higher the amount of pesticide input, the greater threat there is to food security. The higher the disaster degree, the more difficult it is to ensure food security. The greater the effective irrigation area, the more food security can be ensured. The higher the investment in fixed assets, the more possible it is to guarantee food security. Additionally, machinery input, labor input, and infrastructure construction are not statistically significant.

We use the DID method to evaluate the impact of the WRTPP on helping ensure food security. However, the effective premise of the method is that if there is no external impact from the policy, the food production trends of the experimental group and the control group are parallel. To this end, we conduct a parallel trend test.

Based on the practice of previous literature, we draw a comparison chart between the experimental group and the control group to illustrate the changing trend of food production. Figures 1–3, respectively, depict the differences in the total grain yield, the grain yield per capita, and the total yield of three main grains between pilot provinces (municipalities) and non-pilot provinces (municipalities). First, the total grain yield, the grain yield per capita, and the total yield of three main grains in the pilot and non-pilot provinces (municipalities) remained basically parallel before 2014. Second, in 2014 and subsequent years, the increase in grain yield in the pilot provinces (municipalities) has obviously expanded. Various indicators in the pilot and non-pilot provinces (municipalities) show greater differences. This result intuitively shows that the policy has a positive effect on helping ensure food security. Third, the changes in grain yield in non-pilot provinces (municipalities) remain stable, namely the policy does not have a significant negative impact on food production in non-pilot provinces (municipalities). Based on this conclusion, it is helpful to further understand the impact of WRTPP on helping ensure food security.

In order to further verify whether the hypothetical conditions of parallel trends are true, we use the data from the early implementation of the WRTPP to test the common trend. In 2009, 2010, 2011, 2012, and 2013, the trend values were assigned to 1, 2, 3, 4, and 5 to construct a time trend variable (Trend) to analyze the linear time trend of pilot and non-pilot provinces (municipalities). If there is no systematic difference between the time trends of pilot and non-pilot provinces (municipalities) between 2009 and 2013, Treat should have statistically insignificant coefficients. Table 4 lists the results of the common trend. The coefficient of Treat is not significant, indicating that there are similar time trends between the pilot and non-pilot provinces (municipalities). Therefore, our research does not violate the parallel trend assumption of the DID method. Our results are robust.

The baseline result and a series of robustness checks confirm that the WRTPP has a significant role in helping ensure food security. How is this effect realized? This requires further exploration of its mechanism. Therefore, this section further discusses the mechanism of the policy on helping ensure food security from the perspective of water-saving irrigation technology.

Among them, Technology_it represents water-saving irrigation technology, which is measured by the ratio of water-saving irrigation area to cultivated area of each province (municipality). Y_it represents the total grain yield and grain yield per capita. The definition of other variables is consistent with formula (1). We also control the characteristic variables of provinces (municipalities).

Table 5 shows the results of the mechanism the policy works. Column (1) presents the impact of the policy on water-saving irrigation technology. The coefficient of estimator Treat is significantly positive at the 5% level, indicating that the policy can promote water-saving irrigation technology increased by 8.8%. Column (2) further reports the results of the technology and total grain yield. The study found that the coefficient of the technology is significantly positive at the 5% level, indicating that the technology has increased the total grain yield by 9%. The adoption of the technology is conducive to helping ensure food security. Column (3) indicates that the policy can increase total grain yield. It can be seen from the results in column (4) that the coefficient of the DID method estimator Treat is significantly reduced. Therefore, the first three columns in Table 5 show that the policy can increase grain production to help ensure food security by improving the adoption of water-saving irrigation technology. Our hypothesis 2 has been initially verified.

At the same time, we explore the impact of the policy on grain yield per capita by improving water-saving irrigation technology. The results are listed in Table 6. The coefficient of the explanatory variable in column (2) is significantly positive at the 1% level, indicating that the technology can significantly increase grain yield per capita. Column (4) reports the results of formula (5). The coefficient of the estimator Treat is significantly reduced, indicating that the policy increases the grain yield per capita by improving the adoption of the technology. This also further validates our hypothesis 2. That is, WRTPP can improve the adoption of water-saving irrigation technology to help ensure food security.

In order to examine the dynamic effects of the WRTPP on helping to ensure food security, the impact of the policy is broken down into years to observe the changing trend of food production. The results are shown in Table 7. The coefficient of Treat×year₁ represents the impact on grain yield in the first year after the policy implementation. The coefficient of Treat×year₂ represents the impact on grain yield in the second year. The rest can be done in the same manner. The results reveal that the policy has a positive effect on helping ensure food security in the first year and the effect increased after the third year. The promotion effect reached the maximum in the fourth year. Overall, after the policy implementation, food production has been greatly positively affected, indicating that the policy will have a long-term effect on helping ensure food security.

With the development of the international economy and the changing global social and political environment, food security has increasingly become an important issue concerning global food production and consumption patterns. Based on Chinese provincial panel data from 2009 to 2018, we use the DID method to evaluate the impact of China's WRTPP on helping ensure food security and its mechanism. It is found that the policy has a significant promoting effect on food production. After the implementation of the WRTPP, the total grain yield and yield per unit area in the pilot provinces (municipalities) increased, and the per capita share of grain also increased significantly. Furthermore, this effect began to increase after the third year of the policy implementation and reaches the maximum in the fourth year after its implementation. After further analysis of the mechanism, we reveal that the policy can help to achieve a sufficient supply of grain and help guarantee food security by improving the adoption of agricultural water-saving irrigation technology. After a series of robustness checks, the conclusion remains robust. Our conclusions can be used as a reference for other developing countries to alleviate conflicts between food production and agricultural water use.

First, this study confirms that the WRTPP is conducive to helping ensure food security, which enriches the existing research on the factors influencing food security and has important theoretical significance. Existing empirical studies have found that food security is related to many factors, such as water resources (Gohar & Ward, 2010; Hanjra & Qureshi, 2010), land resources (Qi et al., 2018), climate change (Atuoye et al., 2020), and government intervention (Farrukh et al., 2020). However, compared with existing evidence on the impact of other factors on food security, the role of the WRTPP in contributing to help ensure food security still needs further exploration. As a complement, our results demonstrate that the WRTPP can improve grain yields to help ensure food security.

Additionally, this study confirms that the WRTPP can help promote the realization of food security by improving the utilization rate of water-saving irrigation technology. Existing research has shown that the implementation of agricultural water rights can guarantee sufficient supplies to meet the water quota of crops and thus increase crop yields (Li & Guo, 2014). However, few studies have discussed how the WRTPP encourages farmers to adopt water-saving irrigation technology, thereby increasing food production. Thus, from the perspective of water-saving irrigation technology, we have reached this conclusion.

This study provides useful policy implications for effectively solving the contradiction between water resource shortages and food production, namely the need to formulate a scientific and reasonable water right policy, to help promote food security. First, the findings have demonstrated that the WRTPP can help promote food security to a great degree, which fully affirms the development direction of the policy and provides implications for evaluating its effects. Therefore, one policy implication of the study's finding is to suggest that it will be beneficial to further promote these experiences throughout the country and expand the implementation scope of the policy in China. Secondly, the results also indicate that the WRTPP can help guarantee food security by improving the adoption of agricultural water-saving irrigation technology. Therefore, the government must act to protect farmers' water rights, scientifically determine agricultural water consumption and water prices, improve agricultural water-saving facilities, effectively guide farmers to actively adopt water-saving irrigation technology, and ensure the realization of food security through the improvement of technology. Finally, the incentive mode and supporting policies for efficient water-saving irrigation technology should be formulated. Policies should aim to broaden farmers' access to credit information and promote the linkage mechanism between agricultural insurance and loans, which can stimulate farmers' adoption of water-saving irrigation technology to help ensure food security.

However, there are some limitations of this study. Due to the limitation of data availability, food security is merely measured by total grain yield, grain yield per unit area, and grain yield per capita rather than the FAO's comprehensive definition. Furthermore, this paper only investigates the impact of the WRTPP to promote the adoption of water-saving technologies among farmers, the mechanism of WRTPP on helping ensure food security from multiple perspectives can be examined in future research.

The work was supported by the ‘Major Projects of the Humanities and Social Sciences Base of the Ministry of Education (17JJD790015)’; ‘National Natural Science Foundation of China (72103115)’; ‘Humanities and Social Science Research General Project of the Ministry of Education (21XJC790008)’; ‘China Postdoctoral Science Foundation (2020T130393)’.

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