Adoption and sustained use of the arborloo in rural Ethiopia: a cross-sectional study

In rural Ethiopia, only 19% of the population has access to improved sanitation, which has no doubt contributed to high levels of diarrhea, trachoma, and helminth infection. Low-cost sanitation options are needed in Ethiopia, but few studies have assessed their effectiveness and sustainability. The composting arborloo is one such option. Catholic Relief Services (CRS) has promoted the arborloo since 2004. Eighty thousand Ethiopian households have constructed arborloos with their assistance. We assessed the arborloo’s adoption and sustainability in 20 communities that received arborloo promotion. We surveyed 690 households and conducted 24 key informant and 33 in-depth interviews. Over two-thirds [462 (67.0%)] of surveyed households constructed an arborloo; 352 (76.2%) sustained use and 65 (14.1%) moved to a more permanent latrine. There is a clear role for the arborloo in rural Ethiopia to increase the rate of sanitation adoption, sustainability, and movement up the sanitation ladder. We found no evidence that sustainability differed by arborloo age or socioeconomic status. Sustainability was most strongly associated with use of the arborloo pit for planting and a cement slab. Slab subsidy discontinuation after 2012 may negatively impact sustainability. However, CRS sanitation marketing could increase slab access, maintain sustainability rates, and decrease reliance on programing for sanitation solutions. doi: 10.2166/washdev.2015.149 om https://iwaponline.com/washdev/article-pdf/5/3/412/385323/washdev0050412.pdf er 2019 Dionna Fry Matthew C. Freeman (corresponding author) Department of Environmental Health, Rollins School of Public Health, Emory University, 1518 Clifton Rd NE, Atlanta, GA, USA E-mail: mcfreem@emory.edu Dejene Mideksa Yeshewahareg Feyisa Bekele Abaire Catholic Relief Services Ethiopia, PO Box 6592, Addis Ababa, Ethiopia Argaw Ambelu Department of Environmental Health Sciences and Technology, College of Public Health and Medical Sciences, Jimma University, PO Box 807, Jimma, Ethiopia Katherine Cunliffe Catholic Relief Services, 228 W Lexington St, Baltimore, MD 21201, USA


INTRODUCTION
One such low-cost option is the arborloo, an ecological sanitation (eco-san) approach that is designed to utilize composted material for tree planting, which was developed in Zimbabwe in 1998 (Morgan ). By eliminating the barriers of cost and time, the arborloo has the potential to increase the rate of rural sanitation adoption in Ethiopia, which could in turn decrease the burden of sanitationrelated infectious disease (Simpson-Hebert ). As a lowcost technology, promotion of the arborloo is especially well suited to Ethiopia in today's context, since the government implemented a zero-subsidy sanitation policy in 2012.
The arborloo includes a household-dug pit (which should measure 0.8 m wide and 0.5-1 m deep), an optional ring beam to protect the pit, a concrete slab (which should be light and overlay the ground by at least 0.1 m on all sides), and a superstructure (Morgan , ). The household generally provides the labor to dig the shallow pit and build the arborloo, thus this element of the arborloo does not have a monetary cost to adopters who are generally engaged in non-wage labor, although there is an opportunity cost since adopters must invest 2-5 hours in building the arborloo (Morgan , ; Simpson-Hebert ). If the opportunity cost were to be monetized, the household labor costs for digging the arborloo pit range from $0.18 to $0.44 for 2-5 hours of labor (U.S. Department of State ). If the household chooses to include a ring beam, the supplies to make bricks and cement cost $3.5-5. The cement slab costs $5.00-6.60 to purchase, although some households choose to utilize free natural materials to construct a slab. Since the arborloo is moved often, the superstructure should be portable or easily replaceable.
The superstructure is most often made of local materials (woven reeds or sticks), but if purchased, materials for a cement superstructure may cost an additional $10 (Smet ). While an arborloo could cost from $0 (natural materials' slab) to $22 if all materials are purchased, no households surveyed in this study purchased materials for a superstructure; therefore, the cost estimate for the arborloo used throughout this paper is $5-10 (Hebert ; Mara ). The arborloo is a low-cost eco-san option as compared to other eco-san options and improved latrines.
Other eco-san options generally cost between $58 (fossa alterna) and $400 (urine diversion); ventilated improved pit latrines generally cost between $52 and $400, although these figures will vary by country (Smet ). In 2010, a traditional pit latrine with a cement slab cost $32-121 in Ethiopia. The larger, thicker slab costs $15-44 and labor to dig the 3 m deep pit ranges from $17 to $77 (Hansch ; Hebert ). A traditional pit latrine with a slab made out of natural materials (improved or unimproved) costs from $17 to $77 for the labor to dig the 3 m deep pit (Hansch ; Hebert ). These costs are still much higher than those for the typical arborloo latrine in Ethiopia (Hansch ; Hebert ).
After the arborloo is constructed, a layer of leaves, ash, and/or soil is placed in the pit, and the same components are added after each use to accelerate composting and reduce odor and flies (Morgan , a). Once the pit is two-thirds full, which generally occurs every 6 months, the pit is backfilled with a thick layer of soil and a fruit tree is planted on the nutrient rich pit (Morgan , a). The household digs another arborloo pit once the first one is filled, and the concrete slab and superstructure are moved to the new pit ( Figure 1). This process is repeated as pits are filled (CRS b).
The arborloo is considered ecological sanitation (Esrey   Eco-san options generally fall into two overarching categories: (1) urine-diversion latrines separate urine for use and utilize desiccation (drying) to treat feces, and (2) composting latrines such as the arborloo, fossa alterna, and modified Blair latrine that utilize decomposition to treat combined urine and feces excreta (Winblad et al. ).
Since arborloos have shallower pits and the excreta composts relatively quickly (usually 3-4 months) they have a lower risk of groundwater contamination as compared to deeper, unlined latrine designs (Esrey et al. ; Winblad et al. ). The arborloo can also be utilized in waterscarce areas both because the design does not require water and because the crops planted on the arborloo pit may exhibit increased crop resiliency in drought conditions (Esrey et al. ). The shallower arborloo is also a good option in areas where soils are rocky or sandy, as is the case in much of Ethiopia (Morgan ; Simpson-Hebert ; Seremet ). In a 2004 evaluation of their sanitation programs, Catholic Relief Services (CRS) Ethiopia found that the rocky and sandy soils found in much of Ethiopia were unsuitable for the deeper conventional pit latrine or ventilated improved pit latrine designs that they were promoting. Their evaluation found that rocky conditions caused difficulty in digging the 3 m deep pits and sandy soils often caused the deeper pits to collapse once constructed (Seremet ). CRS Ethiopia also found that these two deeper pit latrine designs, which require thicker, more expensive slabs and hired labor to dig the pit, were too costly for the rural Ethiopian population at $60 per conventional improved latrine and $150 per ventilated improved latrine (Seremet ). In response to these issues, CRS Ethiopia began promoting the arborloo, an improved sanitation option, in 2004 in partnership with the Global Water Initiative, since it has a shallower 0.5 m deep pit, a thinner, cheaper cement slab, and therefore a relatively lower cost ($5-10). Since that time, CRS Ethiopia has assisted in the construction of over 80,000 arborloos throughout Ethiopia (CRS a; Tolessa ). In 2012, the Ethiopian government changed its WASH policy to mandate a zero subsidy model. As a result, a household seeking to construct an arborloo must now pay the full cost of the arborloo and seeds/seedlings. The cost of a slab produced by CRS partners is $5-6.60 and the supplies to construct a ring beam are an additional $3.5 (Morgan , ; Simpson-Hebert ; Hebert ). This government policy change necessarily altered the program implementation strategy, and sanitation marketing was prioritized to increase access to slabs and seedlings for purchase through local marketplaces.

Research aims
We assessed the sustained use of arborloos within CRS program areas in rural Oromia region, Ethiopia. By identifying factors that may contribute to the sustained use of arborloos, we provide evidence for implementation of arborloo interventions in rural areas. We also examined arborloo adoption in program areas and factors associated with households beginning arborloo use.

Ethics
The study was deemed exempt by the Institutional Review Board of Emory University, as it was a program evaluation.
Verbal consent was obtained from respondents.

Study design
We used a two-stage, stratified sampling approach, where the three partner organizations operating in distinct geographic areas were each considered as strata. We calculated our sample size based on a 75% chance of households ever having an arborloo, a design effect of 2, 80% power, and a significance level of 0.05. With an additional 10% for non-response, our sampling target was 625 households in 20 communities.
The gott (community) was our primary sampling unit. Our secondary sampling unit, households, were selected by simple random sampling from a census list of all households in the gott obtained from the government, the CRS partner organization, or from community leaders. All households in the gott were eligible for inclusion in the study. The enumerators skipped over a selected household (replacing it with a different one from the census list) if an adult member of that household was not available or if the household declined to participate in the study.

Qualitative data
Key informant interviews (KIIs) and in-depth interviews (IDIs) were conducted by trained researchers in Oromiffa or Amharic according to the participants' preference. CRS staff or partner staff translated the interview responses to English. Rigorous notes were taken and pertinent quotes were recorded in English at the time of the interviews.
Thirty-three IDIs with community members were conducted to examine household level experience with the arborloo and to elucidate the reasons behind the associations seen in the survey data. Interviews were conducted with households who currently had an arborloo (20), with households who had stopped using their arborloo (8), and with households who never had an arborloo (5). Topics covered in the IDIs included the respondents' opinions on and experiences with their arborloo. Respondents were asked about any sanitation-related assistance CRS provided, why they chose to adopt the arborloo or not, and why they stopped using the arborloo if applicable.
Twenty-four KIIs were conducted with community and kebele leaders, health extension workers, WASH committee members, and health development army members. Interviewees articulated the community-wide experience with the arborloo. Leaders were asked about where community members heard about the arborloo, why community members chose to construct the arborloo or not, what community members felt the arborloo's advantages and disadvantages were, and reasons why community members stopped arborloo use. Interviewees also discussed the community's sanitation training and experience with planting on the arborloo pits.

Data analysis
Survey data were entered into Excel 2010 then cleaned and analyzed using SAS 9.3 (Cary, NC, USA). Multi-level categorical variables were combined into logical groups when the cell frequency was less than 3%. Family size was recoded as a categorical variable using the mean family size for rural Oromia region, which is five (Zewoldi ). The number of years since a household built their arborloo was also recoded as a categorical variable with three levels: 0-2 years ago, 3-5 years ago, and 5-10 years ago. McKenzie ), so all non-binary categorical variables used in the PCA were recoded as binary (Vyas & Kumara-nayake ). The number of hectares a household owned was included as a continuous variable to help alleviate data truncation and clustering concerns. The number of various animals owned was recoded from a continuous count to binary variables because these data were skewed. When households had a missing value for one of the categorical SES variables, the household was assigned the median value for that variable; when a continuous variable was missing the mean value for that variable was assigned.
Only 4.9% of households had a missing SES data point.
SES is presented in quintiles with the lowest quintile (1) being the poorest of the poor and the highest quintile (5) being the least poor households.
To account for our sampling design, survey responses were weighted by the probability of selection at the cluster and strata levels. Survey procedures were utilized in SAS 9.3 to account for population variances in the survey design.
We conducted a bivariate analysis using logistic regression to assess determinants of surveyed households ever having an arborloo. We used households self-reported use of present and past latrine types to establish sustained arborloo use. We conducted a bivariate analysis using logistic regression to assess characteristics of the households, their arborloo usage, and the sample that were associated with sustained arborloo use. A multivariate logistic model of factors associated with sustained arborloo usage is presented.
Qualitative data, including field notes on responses and pertinent quotes that were collected on paper interview guides, were organized by respondent and question then entered into Excel 2010. The number of households and leaders expressing the same idea were enumerated and outliers were noted. When enumerated interview data were examined, trends in the interview responses could be perceived and themes emerged; they are presented with the number of respondents who expressed that opinion noted or in ranked order. This allows the reader to establish if the presented opinion was an outlier or if a large number of the interviewees expressed this opinion.

Demographic characteristics
We conducted a total of 690 surveys in 20 communities. The respondents' median age was 35 years (range 18-88 years) ( A vast majority of respondents stated they (558, 80.9%) had a latrine at the time of the survey, while 58 (8.4%) previously had a sanitation facility but did not any longer and 74 (10.7%) never had one; 462 (67.0%) of households reported they had an arborloo at some point. Among those households that had a toilet at the time of the interview, 63.1% currently had an arborloo and 36.9% had a traditional or improved pit latrine (Table 1).

Factors associated with arborloo adoption
We found evidence of a meaningful difference in arborloo adoption by the partner organization (  (Table 2). Some differences were found between arborloo adoption and SES, but there was no clear trend. Respondents also chose to adopt the arborloo because they felt it provided them more privacy and because the design attracted fewer flies than other traditional latrine designs. KII respondents were also asked why some households chose not to adopt the arborloo. Respondents said that households did not adopt the arborloo because they never received a slab (10 respondents), they did not understand the importance of sanitation and hygiene (four respondents), or they already had a different latrine design (two respondents). Leaders also reported that households did not adopt the arborloo because they did not feel like digging the pit or were unable to do so, because it took up too much space, or because the shallow pit was prone to flooding (one respondent each). Some leaders noted that arborloo adoption had increased after community members saw the success early adopters were having with the seedling planting. Community members reported that they chose not to adopt the arborloo because they did not like the design, which necessitates frequent movement of the latrine and reinvestment in the latrine's superstructure with that movement. Other respondents chose not to adopt the arborloo because their household moved locations often, their compound was small, the shallow pit could easily flood, or they felt they were too old to dig the pit.

Characteristics of arborloo intervention households
Of the households interviewed, 502 (72.8%) had received a slab from CRS. Most respondents used that slab for an arborloo (62.8%), but 51 (7.4%) used the slab for a traditional latrine and 16 (2.3%) did not use a slab for a  (Figure 2). Households who did not receive a slab but instead used stone or wood to construct their arborloo top were less likely to sustain arborloo use (POR 0.21 95% CI 0.06-0.81) (data not shown). Of the 105 households that reported building their arborloos more than 5 years ago, 67.6% had sustained arborloo use (data not shown).

Factors associated with sustained arborloo usage
We found limited evidence of an association between self-   (Table 4).

Determinants of sustained arborloo usage discussed in the interviews
The 18 community members who currently had an arborloo and all 24 leaders reported that they found the arborloo to be advantageous to themselves or their communities. Respondents  felt the most important arborloo benefit was the ability to plant on the filled arborloo pit. Leaders also said that the arborloo was safer than the traditional latrine, especially for children, since it was shallow and there was no fear of the cement slab collapsing. Respondents mentioned that it was easier and cheaper to construct as compared with the traditional latrine.
One respondent said, 'I paid 300 birr for the traditional latrine to be built, but I can construct the arborloo myself in an hour' Respondents noted not receiving a seedling or having a seedling die determined their switch to a traditional latrine because they did not see the arborloo's benefit without the agricultural benefit, although this association was not seen in the bivariate analysis. Households sometimes stopped using the arborloo simply because the slab broke. Respondents also felt that the pit filled too quickly, frequent movement of the slab increased breakage, and the pits took up too much space. CI 0.16-0.67).

Discussion
We found strong evidence that arborloo usage was sustained in intervention communities, even after many years. In this study, factors such as pit usage, availability of an affordable or subsidized cement slab, seedling availability and survival, cost, and arborloo planning were found to impact sustainability of the arborloo. This evaluation found no clear relationship between household wealth and ability to sustain arborloo facilities. We found compelling evidence for high rates of arborloo adoption, although there were significant differences in the groups that adopted the arborloo.
We found no clear relationship between SES and arborloo adoption. It is possible that this lack of an association was due to the fact that the slabs were provided free of charge between 2005 and 2012, since having a lower SES may limit access to some of the more costly sanitation materials (Mairena   The ability to use composted excreta as fertilizer is an important advantage to beneficiaries (Dankelman et al. ; Tolessa ). Some interviewees reported that they had switched to a traditional latrine when they did not observe this benefit. This association was not apparent in the survey data, but a 2010 rapid assessment of CRS' arborloo programs in east Africa found that access to seedlings influenced whether or not arborloos were adopted (Hebert In this study, interviewees reported that they chose to adopt the arborloo because the design was cheaper than other latrine options. The arborloo has lower initial investment and capital maintenance costs than pit latrines or VIP latrines, since the slab is cheaper and no hired labor is required to dig the pit (Morgan ; Smet ). The arborloo's lower relative cost ($5-10) as compared to other improved sanitation options could be one reason for the arborloo's high rate of adoption in intervention communities. The arborloo's lower cost could decrease the barrier to acquiring household sanitation; it therefore has the potential to increase the rate of rural sanitation adoption in Ethiopia where it is promoted (Simpson-Hebert ).

LIMITATIONS
There are a number of limitations that could impact the internal and external validity of our findings. We used the responses to the households' present and past latrine types to establish sustained arborloo use, which may be subject to bias. Ideally, the proportion of households in an individual community that initially received a slab could have been used as an indicator for sustained arborloo use; however, this indicator could not be utilized in this case because the slabs were not distributed at the community level.
Since this is a cross-sectional study, no causal relationship can be established. There were a number of missing data points in this study which limited our analysis capacity at times. Seedling survival and where households obtained seedlings could not be used in the multivariate analysis of arborloo sustainability because these data were only recorded if a household reported pit usage. Our multivariate model provided limited analysis since this cross-sectional study is meant to be hypothesis generating.

CONCLUSIONS
Here we present an exploratory study on arborloo adoption and sustained use in a certain place and time. It can help inform research questions for future work, contribute to the body of peer-reviewed literature on the adoption and sustainability of ecological sanitation interventions, and provide evidence for implementation of arborloo interventions in rural areas. This study should not be considered a definitive study that is applicable to all settings.
While this research found that a number of factors were associated with arborloo adoption and sustained use, further research is needed to better understand why and how these factors are associated with adoption and sustained usage.
Better understanding why and how these factors impact arborloo adoption and sustained use could help program implementers inform how they can address these factors in current and future programs in order to improve adoption and sustainability for the groups that were seen to have lower rates of adoption or sustained use.