Legume integration in smallholder farming systems for food security and resilience to climate change

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 1 / 20 OPEN ACCESS Citation: Melese M, Getachew B, Woldemeskel E, Gunnabo AH (2025) Legume integration in smallholder farming systems for food security and resilience to climate change. PLoS One 20(8): e0327727. https://doi. org/10.1371/journal.pone.0327727 Editor: Charles Odilichukwu R. Okpala, University of Georgia, UNITED STATES OF AMERICA Received: July 20, 2024 Accepted: June 19, 2025 Published: August 13, 2025 Peer Review History: PLOS recognizes the benefits of transparency in the peer review process; therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. The editorial history of this article is available here: https://doi.org/10.1371/journal. pone.0327727 Copyright: © 2025 Melese et al . This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, RESEARCH ARTICLE Legume integration in smallholder farming systems for food security and resilience to climate change Meseretu Melese 1*, Bereket Getachew 1, Endalkachew Woldemeskel2, Ashenafi Hailu Gunnabo 1 1 College of Natural and Computational Sciences, Arba Minch University, Arba Minch, Ethiopia, 2 World Agroforestry (ICRAF), ILRI-Addis Ababa Campus, Addis Ababa, Ethiopia * meseretu2023@gmail.com; meseretu.melese@amu.edu.et Abstract A random sample of 847 households (HHs) in southern Ethiopia was used to assess

the impact of HH characteristics, land and livestock ownership, seasonal variations, and agricultural challenges on cereals and legumes, crucial to community livelihoods. A structured survey was integrated into the ODK data collection tool, validated, and used with trained agricultural agents, and analyzed using an R statistical package. Farm productivity was significantly influenced by gender, since male headed HHs produced 25.5% more yield than female headed HHs. Livestock ownership, land cul- tivation, farm productivity and product utilizations were also varied among the HHs. Furthermore, agricultural practices like labor utilization, fertilizer and composite appli- cation, and use of improved seed varieties significantly affected the farm productivity. Besides, maize was identified as the principal and top-priority crop, while common bean (legume) was the second-priority crop for local people. This shows that legumes were important in the region’s agricultural systems, but some farmers experienced reduced productivity due to poor agronomic practices. Consequently, a substantial proportion of farmers (>50%) faced food shortages from February to June, represent- ing the peak of the dry season and the beginning of the rainy season (April to May). Integrating early-maturing legumes in the farming system would help to escape the food shortage periods. Many farmers disclosed that the cost of chemical fertilizers’ was unaffordable, indicating a need for options like use of rhizobia inoculants and showed interest to use on their farms for improved productivities. Introduction

Smallholder farmers in Sub-Saharan Africa have begun to encounter significant alter- ations in their environmental conditions, particularly those related to climate changes. The indicators of climate change, including elevated temperatures, extreme drought

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 2 / 20 conditions, the proliferation of pests and diseases, as well as erratic rainfall patterns [1]. The consequences of climate variability resulting a shortage of food, water deficit, outbreaks of infectious disease of both human and animal diseases, and losses of biodiversity which result in a loss in endemic and adaptive food sources [2]. The region’s overreliance on rain-fed agriculture, climatic changes such as irregular and unreliable rainfall patterns, and rapidly growing populations [3] pose significant con- cerns to food supply [4]. To cope with the impacts of climate change, there is a rising interest in the significant restructuring of agricultural systems throughout Africa that enhances farmers’ resilience to climate change [5,6]. Agriculture is an important sector in Ethiopia’s economy, with a significant con- tribution to the GDP (32.6%), and export share (77%), and 72.7% of the working population is dependent on it [7,8]. Small-scale farmers, who own less than 2 hect- ares of land [7] make up 80% of the population in the country and play a significant role in agriculture. These farmers utilize subsistence farming methods and produce more than 95% of the country’s crops [8]. The main crops produced by those farmers include cereals, legumes (pulses), oilseeds, vegetables, root crops, fruits, and cash crops like coffee and khat, with suboptimal yields [6]. To reduce vulnerability of smallholder farmers, agricultural intensification is needed

to increase the productivity of fragmented plots, maintaining ecological function and increase resilience to shocks [9]. The cultivation of legumes is pivotal in the pursuit of sustainability owing to their capability to assimilate atmospheric N2 through sym- biotic relationships with rhizobia; they furnish organic resources and can mitigate other limitations by enhancing soil fertility [10]. The relation among legumes, sus- tainable intensification, and the improvement of farmers’ livelihoods is extensively documented. Moreover, legumes provide organic inputs that positively influence the chemical, physical, and biological properties of soil, thereby enhancing agricultural productivity [9]. Grain legumes constitute a significant category of staple food crops in Ethiopia, ranking second to cereals, and account for 10% and 87% of the overall annual grain output within the nation, respectively [11]. A comprehensive analysis reveals that legumes constitute 12.90% of the total national agricultural land dedicated to farmlands [9]. More than twelve distinct legu- minous species are cultivated within the country [14]. Among these, four predominant legume species include faba bean (Vicia faba L.) (30%), common bean (Phaseolus vulgaris L.) (19%) chickpea (Cicer arietinum L.) (12%) and field peas (Pisum sativum L.) (14%) [8]. Smallholder farmers have derived significant advantages from legumes as sources of food, specifically excellent sources of proteins for poor farmers [12] and animal fodder [13], as well as tools for soil nutrient enhancement. Both herbaceous

and tree legumes possess the capacity to rejuvenate soil fertility in degraded land- scapes and mitigate the processes of land degradation [14]. Despite the country’s potential for growing the legumes many Ethiopian soils lack essential nutrients such as nitrogen, phosphorous and potassium which are crop yield limiting factors [15]. Among these soil nutrients, nitrogen (N) is an essential macronutrient for plants, and its availability highly influences the plant productivity [16], needing frequent replenishment. Consequently, prompt resolutions to the issues and reproduction in any medium, provided the original author and source are credited. Data availability statement: All relevant data are within the paper and its Supporting Information files. Funding: The research was funded by the Fund for Innovation and Development (FID) and focused on the adoption of Rhizobium Inoculant Technology (ARIT) at Arab Minch University, Ethiopia. Competing interests: The authors have declared that no competing interests exist.

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 3 / 20 pertaining to soil fertility are imperative; chemical fertilizers have historically been advantageous over extended periods; however, their overutilization has resulted in deleterious environmental repercussions [17]. Besides the effect of N-fertilizer on the environment, smallholder farmers often do not afford the prices, have poor access to the fertilizers in their vicinity and consequently produce crops below their potential [18]. Thus, smallholder farmers choose to add legumes as an alternate source of N-fertilizer because of their N2-fixation capability when in symbiosis with soil bacteria called rhizobia [19]. Thus, farmers can fill in geographical and temporal gaps in cropping systems by using intercropping legumes with cereals and rotating their crops [20]. Notwithstanding all the above potential benefits, the area under legume cultivation is small in most farming systems in SSA (Sub-Saharan Africa) [15], with the most prominent legumes being grain legumes because grain legumes have the benefit of supplying immediate returns to smallholder farmers [14]. They can be integrated with all farming systems, as solo crops in rotation with cereals [21], as intercrops between root crops, banana (Musa paradisiaca) or Enset (Ensete ventricosum) [19] and still the yields vary seasonally and across locations [22]. Their inclusion in the farming system still embraces traditional practices with poor or no input supply.

Though it has been claimed that legume cultivation and agriculture have increased in sub-Saharan Africa due to expan- sion, it is not sufficient to feed the population. Adding to this, in remote parts of sub-Saharan Africa inputs and modern technologies are less likely accepted as the technologies slowly reach the areas and farmers have poor access to. So, the farmers are left behind. In Ethiopia, there exists significant potential for legume production; however, the actual output and productivity of legumes remain below this potential. This discrepancy can primarily be attributed to various environmental and climatic influences, inadequate utilization of agricultural inputs, restricted access to improved seed varieties, and sub- optimal extension services. Consequently, this research endeavor has been undertaken to analyze the determining factors of the production status of legumes among smallholder farmers at the household level. The findings were initiated to generate data for measuring the performance of HHs, farming and management practices, vulnerability to climate change, risk aversion strategies, and enhancing production systems. Furthermore, it evaluates pertinent issues regarding strate- gies that warrant governmental attention and intervention, as well as promising methodologies in the relevant contexts. Additionally, we sought to evaluate farmers’ willingness to adopt novel technologies such as biofertilizers to facilitate future intervention strategies. Methodology Description of the study area

The study was done at the South Ethiopian regional government which is situated between approximately 6° 51′ 10″ N, 37° 45′ 16″ E. The area encompasses four of the traditionally defined Ethiopian agro-ecologies such as Kolla, Woina-dega, Dega, and Wurch [12]. However, the region’s main distinguishing feature is a rich and humid midland, home to Ethiopia’s densest rural population. Most districts are densely populated, including the Rift Valley dry plains, such as the Gamo, Konso, and Derashe districts; in contrast, settlements in the South Omo area follow Omo basin and cover a wide geographical area, with sparsely distributed agro-pastoral patches of villages [23]. Agriculture accounts for about 92% of the population’s income and home consumption [21]. Except for Konso, and pastoral areas in Omo valley, the enset based farming system is dominant in the highlands of the region. Teff (Eragrostis teff), maize (Zea mays), barley (Hordeum vulgare), wheat (Triticum aestivum), faba bean (Vicia faba), field pea (Pisum sativum), and common bean (Phaseolus vulgaris) were grown for both commercial and domestic purposes in lowland and midland altitudes of the region. In the study area, the principal cash crops include banana (Musa paradisiaca), coffee (Cof- fee arabica), mango (Mangifera indica), sesame (Sesamum indicum), cotton (Gossypium hirsutum), khat (Catha edulis) and apple (Malus domestica), tomato (Solanum lycopersicum), vegetables and spices. Khat has been expanding and

replacing coffee- and enset-based agroforestry systems in the highlands of most of the study area. Among the livestock,

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 4 / 20 goats, sheep, donkeys, mule, etc. were raised to provide food and income for HHs and used to ploughing land and their manure as natural fertilizer. Farmland holdings in the region are small, thus farmers use numerous cropping methods, including intercropping and crop rotation, to maximize output per unit area and lower the risk of crop failure due to climate change. Intercropping has become a widespread practice in the research area [26], and farmers make additional revenue while alleviating the food scarcity period. Cereals like maize and sorghum are often intercropped with common beans, faba beans, and field pea [24]. About 57 to 100% of the maize production area is intercropped in early and late belg (small rains) seasons with beans [25]. Field peas and faba beans are commonly grown in rotation with barley, wheat, and potatoes in the highlands. For the current study, we purposely selected potential legume producing districts from Konso, Gamo, Gofa, and South Omo Zones based on the information obtained from regional agriculture office. Household (HH) data The HH survey was conducted during 2022–2023. Information was collected on legume and other crop production and production constraints at the HH level from zones (the administrative structure next to the region) and seventeen districts within the zones. From each zones, two to three districts were purposely chosen, taking into account the area size and

population number of the respective districts. Furthermore, the selection process incorporated variations in agro-ecology and the potential for legume production, achieved through consultations with local administrative officials and agricultural expertise from the zones. From each district, three kebeles (the smallest administrative structure) were selected and added to 51 kebeles in two farming seasons and three agro-ecologies (highland, midland and lowland) (S1 Fig). Sampling techniques and sample size determination The study population or farms in the research region were chosen using stratified random sampling. The zones were con- sidered as strata. After determining the required sample size, the proportions used to select the samples from the study area. For determining the sample size for the strata, we adapted the following formula from [26]: n = [∑ ( Ni2∗pi∗ (1 – pi) /wi ) ]/[ (N2∗e2/Z2_ {α/2}) + ∑ (Ni∗p∗ (1 – p)) ] Where n is the sample size needed, N is the total population size, L is the total number of strata (Zone), Z alpha over two is the value of the upper tail probability of the standard normal, distribution Z = 1.96 for α = 0.05 significance level, Pi is the subpopulation proportion of farmers who have knowledge about legume-rhizobium inoculant technology for stratum i and i = 1, 2,…, L, e is the level of precision/marginal error/, Ni is the size of stratum (Zone) i and wi is the estimated proportion of Ni to N Considering N1 = N. Gamo ≤ 35518 N2 = N. Gofa ≤ 35436 N3 = N_S. Omo ≤ 18745 N4 = N. Konso ≤ 26519 N5 = N.

Basketo ≤ 1634 N6 = N. Amharo ≤ 6056 e ≤ 0.035 marginal error. It varies from 1% to 5%, p = 0.50, since no research has been done on this issue and there was no information about p. The sample size n is the equation for n = 779. District agri- cultural experts selected kebeles for a study based on potential and agro-ecology. Data collection Structured questionnaires were designed to collect data on socio-demographic and economic, agricultural, and service- related factors. It also included HH crop production priority (considering legumes, cereals, root crops, vegetables, fruits, and spices), owned livestock, production challenges, and their land holding sizes. The questionnaires were developed in English and then translated into Amharic. Agricultural expertise from districts and agricultural extension workers from each kebele were trained and used for data collection. We used Open Data Kit (https://opendatakit.org), a digital data collec- tion tool and uploaded it to a secured data repository (Kobo Toolbox, https://kobotoolbox.org). In areas where the data

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 5 / 20 collectors failed to use the tool or had no smartphone, we employed paper-based data collection and later incorporated. In this case, an extra 10% contingency was added to the estimated household number, adding the total number of house- holds to 859. To ensure data quality, incomplete and wrongly filled forms were discarded and the remaining was combined with ODK data. Interviews included questions about all legume crop species produced by the household, followed by more in-depth questions about the target legume, the production constraints, the seasonal effect on the production and intensification method, and their perception of rhizobia inoculant technology. Data analysis The collected data were downloaded from the Kobo Toolbox repository, while data collected on paper base were filtered and manually curated before combining with the data downloaded from the tool. In total, 847 household responses were subjected to descriptive and inferential statistical analysis using R software version 4.3.2. Farm sizes were characterized as small (<1 ha) and large (≥1 ha) by slightly modifying the FAO category [27], while livestock owned by the farmers was expressed in tropical livestock unit (TLU) and categorized as small and large TLU according to Tache et al. [28]. Correla- tions between demographic variables and farmers’ productivity were analyzed using the agricolae package in R software.

Similarly, multiple linear regressions were used to evaluate the effect of different farm factors on the farmers’ productiv- ity. We employed the ggplot2 package to visualize the results of the analysis. Results Demography of the households To study the factors influencing farm productivity and livelihoods of the farmers, 847 HHs were interviewed, and their responses were analyzed. Accordingly, the ages of the respondents (HHs) ranged from 21 to 83 years of age. The aver- age family size of the HHs was 6.81, representing on average a large family size and a preponderance of rapid population growth in the country. HHs from pastoralist areas had the maximum number of the family size (20), with large farm size holding capacity. The HH size in adult equivalent scale (AES) was estimated to be 4.74. The educational qualifications of the participants were delineated as follows: individuals categorized as illiterate constitute 44.46%, those who have completed primary education account for 39.1%, respondents with secondary education represented 13.22%, and those who have attained post-secondary or university degrees comprised 3.31% (Table 1). Given this, the educational level of the head of the HHs had no effect on agricultural output in the area, since their productivity (in tons) did not differ probably due to lower proportion (3.31%) of the HHs heads with Post-secondary education and above. Relating the demography of the HHs to total Table 1. Household characteristics. Variables Category No. Percent Productivity (in tons) Sex of HH head Male 794 93.74 3.13 ± 0.70

Female 53 6.26 1.86 ± 0.41 Age of the HH Male 21-83 Na 1.86 ± 0.41 Female 30-55 Na 3.13 ± 0.70 HH head Educational Illiterate 377 44.51 2.32 ± 0.41 Primary 331 39.79 2.50 ± 0.43 Secondary 112 13.22 2.82 ± 0.51 Post-secondary 21 2.48 2.58 ± 0.87 University 7 0.83 2.23 ± 1.38 HH Size (AES) Mean of AES 4.74 ± 0.61 Na Na Where: HH = households; AES = Household size in adult equivalent scale, Productivity = Mean farm productivity per year, Na = not estimated. https://doi.org/10.1371/journal.pone.0327727.t001

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 6 / 20 farm productivity (aggregate farm product per year divided by land farmed in that specific year) was not surprisingly differing among the HH educational status. As the level of the HH head education increased, farm productivity did not improve. On the other hand, male-headed HHs had significantly higher mean farm productivity per year per hectare, probably since male- headed HHs had access to farm inputs, more formal interaction with agricultural extension service providers, and become better in adopting varieties & implementing agronomic management (Table 1). The study explores the relationship between family size and crop production in a region, revealing that larger families face challenges in food insecurity due to limited resources sharing, and addressing this requires enhancing cropping intensity and diversification. In terms of land possessions, some respondents had no arable land and relied on the cottage industry for a living, while the largest land possession reported was 8 ha (Table 2). The farmers annually cultivated between 0.1 and 6 hectares of the arable land mentioned, resulting in significant diversity in both agricultural practices and crop yields. Production records indicated that a maximum of 16 tons was harvested per year, contrasting with the minimal yield of 0.1 tons during the same period, highlighting the wide range of output across farms. Majority of their output was used for domestic use (in most cases up to 90%) and savings during tough times (common

for farmers with surplus farm produce) that have been strongly varied from 10–90% among the HHs. Wealthier farmers or households sold enough to generate income and have modest living and sent their children to school. Livestock possession was predominantly concentrated in lowland regions, with the highest of TLU (38.52) documented in the pastoralist territories of the South Omo zone. A limited number of individuals residing in the highland areas of the region exhibited a complete absence of livestock ownership, resulting in a pronounced variability in livestock possession at the individual household level. Consequently, the data demonstrated considerable variability, accompanied by excep- tionally high standard deviations (Table 2). Farm challenges cross the study area Most people in the study area depended on agriculture for their livelihood, and agricultural goods were their main source of income. Population increases shrunk the farm sizes and made the people farm more fragmented land, affecting their entire productivity. The growing population and its effects on development and agriculture have been the subject of con- tentious debate locally and globally. In the current study area, there was a conversion of natural forests, sacred forest, and uncultivable areas into farmlands (personal observations during survey of the study sites), indicating the challenges of land shortage and the strategy of the communities to cope with challenges. Land fragmentation

The research sites displayed a noteworthy degree of land fragmentation, despite the continual expansion of agricultural territories and the establishment of new settlements in remote regions. Land fragmentation intensity has been defined at the district and zone levels within the research area (Fig 1. tif). Table 2. Farm characteristics owned by the households. Variables Mean sd Min Max Arable land (ha) 1.71 1.21 0 8 Land cropped 1.33 0.95 0.1 6 Product in tons/farm/year 2.89 2.94 0.1 16 Farm product sold (%) 18.59 15.52 25 75 Farm product consumed (%) 68.07 23.4 10 90 Farm product saved (%) 12.02 12.78 10 90 Tropical Livestock Unit (TLU) 5.2 4.22 0 38.52 https://doi.org/10.1371/journal.pone.0327727.t002

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 7 / 20 At the zone level, small-scale farmers in Basketo, South Omo, and at lower altitudes of Gamo zones exhibited larger farmland (>2ha) holdings, while considerable number of farmers experienced farmland fragmentation (<2.0 ha) in Konso, Gamo, and Gofa highlands (Fig 1a, S2 Fig). Not surprisingly, at district level, all farmers cultivated <2ha farm sizes, except for North Ari district (Fig 1b). The allocation of land per household (6.8 persons/HH) was found to be insufficient for food production (S2 Fig). Subsequently, younger HH members started migrating to urban areas, while others were looking for non-agricultural practices. Tropical livestock unit (TLU) In the study area, mixed farming and pastoralist practices were common. Most respondents had a variety of livestock spe- cies that constituted local breeds and reared using low-input/low-output husbandry techniques. Residents in pastoral regions had the largest number of tropical livestock units (TLU) compared to HHs living in other lowlands that practiced crop-livestock mixed farming. The highest TLU was estimated for farmers residing in South Omo, where the pastoralists live in the region. Despite the effect of drought (climate impact) on the livestock population in the pastoral area, still a substantial number of TLU was recorded from the area (S2 Fig; Table 2). In the lowlands of Gamo, farmers focused on fruits mainly banana and

vegetable productions, and had a small livestock population when compared to pastoralist areas but had a large population when compared with the highland and midland dwellers. Nowadays, in Gamo low lands, the farmers are changing forests and grazing lands to banana plantations, which reduced the number of livestock being reared by the HHs (S3 Fig). Farmers who possess a significant number of TLU primarily utilizing oxen for ploughing tend to yield a greater number of cereals in comparison to legumes. This can be attributed to the fact that utilizing oxen for ploughing allows farmers to Fig 1. Farm sizes by zone (a) and by district (b). shows the average farm size per household in hectares by zone (a) and district (b). The figure illus- trates the spatial variation in farm size distribution by comparing mean landholding sizes across districts (subdivisions within zones) and zones (adminis- trative units below the regional level). https://doi.org/10.1371/journal.pone.0327727.g001

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 8 / 20 effectively cultivate larger areas of arable land, which in turn influences their preference for growing major cereals such as maize, teff, wheat, and barley (S4 Fig). Agricultural intensification To feed the growing national and regional populations, agricultural intensification through organic/chemical fertilizers and improved agricultural practices have been recommended. Accordingly, besides chemical fertilizers, organic fertilizers such as animal manure, compost, green manure and biofertilizers have been in use for over decades. In the current study area, manure application was common among HHs living in highlands, whereas those living in lowlands possessed many live- stock but rarely used manure or compost to improve their farm fertility (Table 3). Table 3. Farm practices affecting mean farm produce per ha per year. Farm characters No. % Mean farm product (ton/ha/year) HHs that hired labor 219 25.86 2.43a HHs that not hired labor 628 74.14 1.84b HHs that used organic fertilizer 377 44.51 1.98b HHs that not used organic fertilizer 470 55.49 2.13 a HHs that used compost as organic fertilizer 193 22.79 1.94a HHs that not used compost as organic fertilizer 654 77.21 2.10 a HHs that used manure as organic fertilizer 240 28.34 2.05a HHs that not used manure as organic fertilizer 607 71.66 2.07a HHs that fertilized legumes 139 16.41 1.91 a HHs that not fertilized legumes 704 83.59 2.10 a HHs that used urea fertilizer 653 77.10 2.11 a

HHs that not used urea fertilizer 194 22.90 1.92 a HHs that used DAP fertilizer 218 25.75 2.58a HHs that not used DAP fertilizer 629 74.26 1.87b HHs that used NPSB fertilizer 343 40.41 1.81b HHs that not used NPSB fertilizer 504 59.50 2.24a HHs that believe their farms have poor soil fertility 55 6.49 1.69b HHs that believe their farms have moderate soil fertility 665 78.51 2.12a HHs that believe their farms have good soil fertility 127 14.99 1.93ab HHs that have hilly farms 119 14.05 2.17ab HHs that have plain farms 525 61.98 1.93b HHs that have valley farms 203 23.97 2.35a HHs that reported occurrence of pests on their farm 385 45.45 2.14a HHs that reported no occurrence of pests on their farm 462 54.55 2.00a HHs that reported occurrence of weeds on their farm 729 86.07 2.14a HHs that reported no occurrence of weeds on their farm 118 19.93 1.61b HHs that reported occurrence of disease on their farm 665 78.51 2.01b HHs that reported no occurrence of disease on their farm 182 21.49 2.27a HHs that have knowledge about rhizobium inoculants 25 3.00 2.14a HHs that have no knowledge about rhizobium inoculants 822 97.00 2.06a HHs that reported drought in the farm 652 73 2.07a HHs that not reported drought in the farm 195 27 2.06a HHs that used rhizobia inoculant 0 0.00 0.00 Treatments with the same letter were not significantly different. https://doi.org/10.1371/journal.pone.0327727.t003

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 9 / 20 Many farmers apply urea, diammonium phosphate (DAP), or blended NPSB to enhance their crop yield and sustain soil fertility (refer to Table 3). A diverse spectrum of chemical fertilizer applications (ranging from 0 kg to 100 kg per hectare) was reported within the region, with some exceptional instances surpassing 100 kg/ha (illustrated in Fig 2. tif). In general, the predominant proportion of farmers utilized 50 kg of fertilizer per hectare, whereas a minority resorted to using 120, 150, 200, or 300 kg of fertilizer per hectare. An inadequate amount of fertilizers (<50 kg/ha) was observed among farmers from the Gamo zone. Notably, an extraordinary application of 200 or 300 kg of fertilizer per hectare was recorded in South Omo. Despite the reported suboptimal agricultural outputs, the majority of households (77.10%) incor- porated urea into their farming practices. As shown in Fig 2, those farmers applied exceedingly small (mostly <50 kg/ha) quantity of fertilizer that might not contribute to the yield. However, as indicated above, application rates remain significantly below the required level. The HHs from the high- lands believed that their farms had good soil fertility, but the yield reported was lower than the farmers who believed that their farms had moderate soil fertility but that productivity could be increased by hiring labor. The use of organic and chemical fertilizers did not result in significantly higher yields compared to farmers who did not

adopt these agricultural practices. However, the application of chemical fertilizers generally enhanced productivity, with the exception of treatments involving NPSB, which did not exhibit a positive effect. Interestingly, 62% of the farmers had plain land and produced 3.61 tons of mean farm product per hectare, which was 1.05 tons higher yield than the yield from valley lands. Some farmers reported using fertilizers against legumes, but their yield was lower than those who did not use fertilizers. The key objective of this study was to know about the use of rhizobia inoculants in the region and only 3% of the farmers heard about it but they never used it. Some HHs reporting no problems with weeds, pests, diseases, and droughts on their farms and they had better farm products. Briefly, challenges encountered on farms more importantly affected the yield of the farmers than the effects of using fertilizers and employing labor. Diversity of crop on farm and farmer’s priority crop It has been a long time since intervention was introduced to farms to improve farm productivity in sub-Saharan Africa. One of such interventions was farm intensification that focused on introducing crop diversification on farms. To understand the diversity of crops growing in smallholder farmers’ field and priority crops of the households, farmers were asked to list type of crops ever grown on their farm. More than 20 crops were recorded, of which maize, sorghum, wheat, barley and teff were reported as the first five priority crops on the farm (Fig 3. tiff).

It was recognized that the cereal crops were the primary crops grown on the farms across the study area (with some exceptions) while the legumes become the second priority crops. Among the legumes, common bean was the number one crop among the second and third priority crops. It was succeeded by sorghum, teff, and maize. The dominance of the common bean as the second and third priority crops would reflect its longtime adoption in the region. The degree of legume intensification within the region was notably suboptimal. Only 16.41% of farmers apply chem- ical fertilizers in conjunction with local legume varieties (refer to Table 3). Conversely, a respectable number of farmers cultivated improved seed varieties without the application of fertilizers on their farms. Among the improved common bean varieties, Nasir, Red Wolayta, Acos, Hawassa Damue, and Sari119 were identified, whereas the maize varieties BH540, BH541, and BH548, along with the sorghum varieties Mirti Zer, Merera, and Gudina, were acknowledged by the farmers. These improved seed varieties were released by agricultural research centers and subsequently introduced to the farming community by agricultural extension agents. 98% of the respondents confirmed that with improved varieties application of fertilizers boosts crop yields. Legume production and potential in the region The primary objective of this research was to ascertain the potential for legume production and its challenges and evalu-

ate the application of rhizobium inoculant (biofertilizer) in enhancing the quality of legume crops in the study site (Fig 4. tiff.

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 10 / 20 This information was sought to use in the development and execution of legume-rhizobium inoculation technology in the area, aiming to amplify legume yield among indigenous farmers. Thus, the survey investigated legume productivity in the region, finding common bean as the most important legume crop accounting for 45% of the yield. Cowpea follows at 16%, while faba bean and groundnut showed potential for development. Significant legume cultivation was observed across all the three agro-ecologies (Kola, Woinadega and Dega), needing developing a center for their appraisal (Fig 4a). The majority of those legumes’ diversity was recorded in the Gamo zone while a respectable number of them grow in Konso zone. Hence, we further explored the potential of the legumes in Gamo and Konso zones to show the two contrast- ing cases. In both zones, common bean was the most produced legume (84% in Konso and 41% in Gamo) (Fig 4b, 4c). Besides common bean, mung bean became the second most important legume crop, which was recently gained the attention of the farmers due to its market value and being one of the Ethiopian Commodity Exchange (ECX) crops. The mung bean has become a commercial crop in Gofa zone and is rapidly expanding and gaining momentum in other parts of the region. However, farmers reported severe damage to the crop by pests and declining market value, demanding for intervention. On the other side, a greater variety of legumes grew in Gamo than in Konso, reflecting variations of legume

cultivation between the zones in the region. To that end, only 3% of the farmers know about the rhizobia inoculants but never use it to enhance legume productivity (Fig 4d). Fig 2. Average fertilizer application (kg/ha) during a single cropping season across the study area. And it also shows the mean fertilizer usage per hectare and compares variation in application rates within the zone. https://doi.org/10.1371/journal.pone.0327727.g002

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 11 / 20 Farm problems A number of factors affecting farm productivity have been reported. As such, farmers experienced climate change induc- ing irregular rainfalls, droughts, incidence of pests and diseases, etc. Majority of the HHs (73%) reported the occurrence of drought on their farm. The drought, exceptionally limited crop production in lowlands of Gamo, South Omo, Konso, and Gofa that faced greater risks of climate fluctuations (droughts and short rainfalls) spilling over several months (Fig 5.tiff). Besides drought, farmland topology induced variations in farm productivity due to runoff. Consequently, farms on sloppy and valley areas had low productivity. Farmers were expanding farms into hilly terrains primarily driven by the limited availability of land, making the problem more intense. Other important factors on the farm include pests and diseases. The abundance of pests varied across zones and destrict, probably linked to agro-climatic conditions of the areas. Nearly 50% of HHs reported pests on farms, while 78% claimed that diseases on their farms (Table 3). The farmers believed that improved seeds would tolerate diseases and pests, and they were requesting for the seeds as well as inputs that they can access at their vicinities (S5 Fig). Food shortage months of the year To explain the food self-sufficiency of the farmers throughout the region, the months of the year that the farmers experi-

ence drought and food shortage was assessed. The region experiences two distinct cropping seasons, namely, Meher and Belg, allowing the farmers to produce twice a year. Meher allows the farmers to grow crops from June to September and harvest in October while Belg allows crop to grow from March to May [29]. Accordingly, farmers experienced food shortage over several months from January to July, though the magnitude var- ied from month to month. From February to June, majority of the farmers (>50%) experienced severe drought and had no Fig 3. Crop priority selection at the household level in the research region. As a reflection of regional preferences for crop production, the figure shows the first, second, and third priority crops chosen by households. https://doi.org/10.1371/journal.pone.0327727.g003

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 12 / 20 Fig 4. Legume production potential (4a) and farmer knowledge of rhizobia inoculation in the study area. The figure compares the most and least diversified legume-producing zones (4b&c) and presents farmers’ access to information and knowledge about rhizobia inoculation(4d). https://doi.org/10.1371/journal.pone.0327727.g004 Fig 5. Food Shortage months in the study area. shows the study region’s seasonal distribution of food shortages. The months with the highest rates of food scarcity (peak hunger months) and those with little to no reported food shortage are shown in the figure. Patterns of food insecurity at the house- hold level throughout the year are reflected in the seasonal trend. https://doi.org/10.1371/journal.pone.0327727.g005

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 13 / 20 sufficient food to feed the household. The pick of the food shortage was reached in May and thereafter started to sharply drop, since the respondents begun harvesting of vegetables and early maturing crops like legumes such as common beans in June, the end of Belg season. In the region, two distinct rainy seasons such as Meher and Belg are wet seasons, allowing the farmers to produce twice a year. Meher allows the farmers to grow crops from July to September and harvest in October while Belg allows crop to grow from March to June. Given those conditions, farmers had sufficient food from July to January, but their farm produce was not sufficient to use in the drier months (Fig 5). Discussions As Sub-Saharan, the country’s economy depends on agriculture [30]. Since the country’s food production potential did not fulfill domestic demand, it imports a huge amount of food and industrial products that cost billions of dollars. It covers the costs from international donations, remittances, and domestic revenues. To fulfill its food production for self-sufficiency, the country has started massively transforming its agriculture, adopting several new agricultural practices and innovative technologies. Several universities and agricultural research centers have been playing a vital role in adopting and intro- ducing new and innovative agricultural technologies into the country [31]. Rhizobium inoculant technology is one of such

agricultural technologies being effectively used in in other countries, but poorly used in Ethiopia [32], particularly in south- ern Ethiopia. To adopt and use the rhizobium-inoculant technology in smallholder farmers’ fields, this study was initiated to generate data for measuring the performance of households, farming and management practices, and vulnerability to climate change and legume production potential. It further wanted to generate first-hand information on the farmer’s liveli- hood and their willingness to adopt the modern technologies like biofertilizers for future interventions. Accordingly, survey data were collected in the regions and described household characteristics, farm variability, agricultural practices, farm problems, climate factors and interest of the farmers towards adopting the rhizobia inoculant technologies. Farm variability across the study area Farm variability refers to the variations in soil composition, crop types, agricultural practices, pest infestations, plant varieties, altitude, soil moisture, soil nutrient levels and harvest outputs from farms within a specific spatial and temporal context. The region’s farming systems were distinguished by significant crop-livestock farming systems with high crop diversification and livestock holding. The diverse agro-ecological settings provide for a variety of farming and livelihood systems [34]. Drought, one of the region’s climatic factors, has been identified as a significant impediment to people’s

cropping preferences [36]. Farmers plant a mix of co-staples and annual crops to meet their nutritional needs, and they frequently incorporate income crops [28]. As a result, these farms are mixed subsistence agricultural systems that provide significant self-reliance and long-term existence for these populations [35]. As a result, in the research region, the reali- zation of subsistence systems focused on the extensive cultivation of Enset-Coffee-Khat dominant agroforestry cropping systems throughout the highlands, while maize and sorghum combined with common bean production systems were common in the low and midlands. Land fragmentation is the growing of crops on disconnected smaller plots [34]. It is more prevalent in the research area, particularly in places with high and medium altitudes, where population growth is high. It is seen as a top concern, and hence its influence has been seen through the lens of farm efficiency and economies of scale [35]. According to CSA [9] and Belay et al. [35], the population boom, customary land inheritance regulations, and farmers’ usufruct rights are projected to contribute to increased fragmentation. This suggests that the farms they inherit become incredibly small- scale operations that are incapable of becoming productive even with intensification, and certainly not sufficient for the extension programs that primarily focus on technology diffusion to address the problems of rural poverty. Reduced land size led to considerable reductions in yields of the key crops on which the population relies for food and livelihood security

(S7 Fig). Even after a single farming season, respondents revealed that yield reductions fell below their household feed requirements. Because of this, small farm fields did not yield as much, while the fields were farmed on a continual basis

ers were obliged to use chemical fertilizers. The Enset-Coffee-Khat based farming systems in the highlands had better organic fertilizer application practices than other farmers. Agricultural practices and intensification A considerable proportion of the populace areas in rural regions experience the detrimental effects of malnutrition and persistent food insecurity [33]. Food insecurity was more prevalent in pastoralist areas and dry rift valley lowlands districts than in highlands. This was true for chronic food insufficient areas when prolonged drought occurs. During the period of this survey, the lowlands of Gofa (Demba Gofa and Zala), Gamo (Garda Marta of Kamba district) and Konso (Kolme and Karat Zuria districts) were experiencing severe food shortage due to prolonged droughts that had consequences on their agricultural intensification. In light of the previously mentioned issue, Ethiopia has made notable advancements in enhancing agricultural output over the recent decades. Nevertheless, despite these positive developments, the levels of yield and overall intensification have continued to be low. In the region, the intensification system has given prominent attention to the distribution and adaptation of chemical fertilizers in ensuring food security but the promotion of improved seeds, which are considered the core of improvement, has less effort from the extension service providers [34]. We observed the extent to which farmers utilized farming technologies and practices commonly recommended by extension services and government authorities.

Regarding chemical fertilizer applications, previously the government had an annual plan to provide fertilizers on a credit base system to the farmers and it was the mandate of agricultural sectors and political leaders because it was con- sidered integral to the sustainable improvement of agriculture [10]. Now, the farmers adopted the chemical fertilizers, and they claim that their farms did not give enough yields without the use of chemical fertilizers. However, the rising costs and in inaccessibility of the chemical fertilizers in their vicinity was severely affecting their farm productivity. A significant number of smallholder farmers have gained access to improved varieties and technologies through the national agricultural extension system and different technology scaling projects (20). However, it was also observed during the survey and discussion that the farmers were facing seed problems, pests, and disease for which they need improved and resistance varieties. As the current result shows that farmers were growing diverse crops on the farms, which is a result of intensification, reflecting distribution of improved varieties to the area. Crop diversification is thus one of the farm intensification methods that farmers adopted it in most parts of Ethiopia [35]. The same authors also reported that farmers were adopting the use of improved agricultural practices like increasing on-farm tree planting, soil and water conservation, adjusting planting dates, and crop diversification.

PLOS One | https://doi.org/10.1371/journal.pone.0327727 August 13, 2025 15 / 20 These practices become now an integral part of the farm practices in some parts of the study area, yet others have to adopt them. This is common in the Rift Valley of the current study area where climate change and variability are mani- fested through frequent droughts and floods, erratic rainfall and fluctuating mean temperatures [36]. So, crop intensifica- tion in those areas was less likely practiced. Legume production and potential in the region Legumes are the key component of Ethiopia’s smallholder agricultural systems [37]. They are easily adapted farms and used as feed for livestock or as food for humans in a variety of processed forms [38]. These crops are commonly known as “poor man’s meat” because they are crucial to the diets of millions of people in developing countries [39]. Grain legumes are among of the most significant commodities in the study region, after cereals making smallholder farmers to produce diverse of them. More than a dozen different legume species have been growing in some parts of the study area. For instance, in Gamo zone, people adopted growing faba beans, field peas, cowpeas, mung beans, common beans, groundnuts, pigeon pea, etc., making the area one of the potential legumes growing sites. The legumes contribute to smallholder farmers’ income as a more valuable crop than cereals, and to diet as a cost- effective source of protein, accounting for around 15% of protein intake and the land coverage increases in all agro-