Water scarcity increasingly constrains vegetable production in dry subhumid and semi-arid agroecosystems where smallholder irrigation systems dominate. This study quantified crop water requirements and irrigation scheduling patterns for major vegetable crops cultivated in Ndeiya, Kenya, using the FAO CropWAT 8.0 model. Household survey data from 397 smallholder farmers, laboratory-derived soil hydraulic properties, and climatic data (2014–2024) were integrated to parameterize CropWAT simulations for cabbage (Brassica oleracea var. capitata), tomato (Solanum lycopersicum), and small leafy vegetables including kale (Brassica oleracea var. acephala), spinach (Spinacia oleracea), African nightshade (Solanum scabrum), and amaranth (Amaranthus spp.). Seasonal crop evapotranspiration (ETc) ranged from approximately 420–520 mm for cabbage, 480–610 mm for tomato, and 350–430 mm for small leafy vegetables depending on production season. Effective rainfall contributed about 57% of crop water requirements during wet seasons but declined to less than 20% during dry seasons, where irrigation supplied more than 80% of total crop water demand. Growth-stage analysis showed that development and mid-season stages accounted for over 60% of seasonal ETc across all crops, with tomato exhibiting the highest peak water demand. Simulated irrigation schedules indicated net irrigation requirements exceeding 350 mm during dry-season production, with irrigation frequency strongly influenced by saturated hydraulic conductivity, which ranged from 1.58 to 34.35 cm h⁻¹.Comparison with farmer irrigation practices revealed predominant reliance on manual watering methods involving large and infrequent water applications, which increases the risk of deep percolation losses. The results demonstrate the importance of integrating locally calibrated climatic, soil, and crop data into irrigation modelling frameworks to improve irrigation scheduling and water-use efficiency in smallholder vegetable production systems within water-scarce environments.

IntroductionGlobal climate change alters the spatiotemporal distribution of soil water, reshaping plant water use strategies in water-limited ecosystems. However, seasonal shifts in plant water-source use and uncertainties associated with different water-source partitioning approaches remain insufficiently quantified in desert steppe ecosystems.MethodsUsing stable hydrogen and oxygen isotopes combined with soil water content (SWC), we investigated the seasonal water sources of Stipa klemenzii and Cleistogenes songorica in a desert steppe in Inner Mongolia from May to September 2025. Three approaches, the Direct Comparative Method (DCM), IsoSource, and MixSIAR models, were applied to identify and quantify plant water sources.ResultsThe results showed that SWC in the 0–5 cm layer exhibited pronounced temporal variability and isotopic enrichment due to evaporation, whereas stability increased with depth. The 20–40 cm layer, constrained by a calcic horizon, served as a stable and isotopically depleted water source during the late growing season. The MixSIAR model exhibited superior performance in quantifying water source contributions compared with the DCM and IsoSource approaches. Both species predominantly utilized water from the 0–10 cm layer during the early and peak growing stages, shifting to water from the 20–40 cm layer when shallow moisture became limited later in the season. Under intensified competition for surface soil water, C. songorica increased its reliance on 10–20 cm water, thereby reducing hydrological niche overlap with S. klemenzii. The proportional similarity (PS) index peaked in July–August, indicating intensified hydrological niche overlap during the period of maximum water demand.DiscussionThese findings demonstrate depth- and season-dependent water partitioning among dominant herbaceous species in the desert steppe and highlight the importance of Bayesian isotope mixing models for quantifying plant water sources under changing precipitation regimes. The results provide insights into the adaptive water-use strategies of desert steppe plants in response to future climate change.

Agricultural intensification in Eastern Africa has raised concerns about the transport of pesticides and nutrients from farmland into surface waters, posing risks to ecosystems and human health. This study systematically reviews the peer-reviewed literature published between 2010 and 2024 to assess the extent, patterns, and drivers of agrochemical contamination in rivers, lakes, and reservoirs across the region. Reported pesticide concentrations ranged from <0.01 to 0.55 μg L−1, with several studies indicating exceedances of drinking-water or environmental guideline values, particularly for organophosphate and carbamate compounds. Nutrient enrichment was widespread, with nitrate concentrations of 0.99–5.6 mg L−1 and phosphate levels of 0.16–2.0 mg L−1, frequently linked to eutrophication. Many studies showed strong seasonal variability, with higher concentrations during rainy periods due to increased runoff and erosion. Variability among findings reflected differences in land use, catchment characteristics, sampling design, and analytical approaches. Where evaluated, mitigation measures such as vegetated buffer strips, cover cropping, and improved nutrient management were associated with reductions in agrochemical runoff of approximately 50–80%. Overall, agrochemical contamination is widespread across Eastern African basins and influenced by agricultural practices and hydrological dynamics, highlighting the need for strengthened monitoring, improved stewardship, and broader adoption of mitigation strategies.

Smallholder farmers in semi-arid regions worldwide face persistent water scarcity, declining soil fertility, and increasing climate variability, which constrain food production. This study investigated soil and water management practices and their effects on soil health, crop productivity, and adoption among smallholder vegetable farmers in a semi-arid area in Kenya. A mixed-methods approach was employed, combining survey data from 397 farmers with a randomized field experiment. Results showed that hand watering (88.7%) and manure application (95.5%) were prevalent, while only 5.7% of farmers used drip irrigation. Compost and mulch treatments significantly improved soil organic carbon (p = 0.03), available water capacity (p = 0.01), and gravimetric moisture content (p = 0.02), with soil moisture conservation practices strongly correlated with higher yields in leafy green vegetables (R = 0.62). Despite these benefits, adoption was hindered by high water costs (42.6%) and unreliable sources (25.7%). Encouragingly, 96.2% of respondents expressed willingness to pay for improved water systems if affordable and dependable. The findings stress the need for integrated water-soil strategies supported by inclusive policy, infrastructure investment, and gender-responsive training to enhance resilience and productivity in smallholder farming under water-scarce conditions across sub-Saharan Africa and other regions globally, contributing to global sustainability targets such as SDG 6, 12 and 15.

Rangelands are essential ecosystems for livestock grazing, wildlife conservation and other uses. However, East African rangelands face multifaceted challenges of land degradation exacerbated by climate change. This study examined the impact of manure and grass-legume mixtures on herbaceous plant species diversity, cover, and biomass production in the Karamoja border region between Kenya and Uganda. Using a randomised complete block design, four treatments, these being grasses (G), grasses with legumes (G+L), grasses with manure (G+M), and grasses with legumes and manure (G+L+M), were applied to the study sites, alongside natural regeneration and open grazing areas. A total of 97 herbaceous species were identified, with 66 species recorded in West Pokot and 54 in Napak. The dominant species were Bothriochloa insculpta in West Pokot and Heteropogon contortus in Napak. The reseeded grasses Cenchrus ciliaris and Chloris gayana were more frequent in the West Pokot and Napak sites, respectively, while Macroptilium atropurpureum was the most frequently-occurring legume across both sites. Natural regeneration and the G+L treatment exhibited the highest species diversity (12 species) while G+M treatments yielded the highest biomass, attaining 1 458 kg ha-1 in West Pokot and 2 299 kg ha-1 in Napak. The findings highlight the potential of integrating native grasses, forage legumes and manure to restore degraded rangelands and enhance forage production.

As nitrogen pollution increasingly threatens water quality in the Lake Victoria Basin, it is essential to investigate the spatial factors influencing nitrogen source use. Understanding these determinants is crucial to inform effective strategies to combat eutrophication, enhance nutrient management, ensure food security and promote sustainable ecological development. This study investigated spatial variation of N sources, the farmers' socio-demographic and farm characteristics factors influencing farmers' choice of nitrogen sources. Data was collected from 1,500 farmers between October and December 2020. The farmers were randomly selected in Kenya, Rwanda, Uganda, Burundi and Tanzania country sub-basins within the Lake Victoria basin (LVB). Spatial autocorrelation was used to evaluate the spatial variation of the nitrogen sources while the Optimized Parameter Geographical Detector (OPGD) model was used to identify the factors influencing the choice or use of N sources. The OPDG results indicate that the country of residence and livestock ownership are the primary factors accounting for 31.9% and 22.1% of the variation in nitrogen sources across the entire Lake Victoria Basin, respectively. The major sub-basin factors influencing the use of N sources were both farm characteristics (types of crops grown and farm size) and social socio-demographic factors of the farmer (education). These findings highlight the need for tailored strategies, accounting for geographical variations, farm characteristics and socio-demographic factors are essential when formulating nitrogen management strategies and policies at local and regional scales within the LVB.

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Strawberries are a valuable crop in Kenya with the potential for significant economic contributions. However, strawberry production in the country has been facing considerable challenges, impacting its economic potential. This study examined the influence of organic manure on strawberry growth and characteristics in Kabete and Mbooni areas in Kenya. The study used a randomized complete block design (RCBD) with three replications. Treatments included livestock manure (well composted mixture of chicken, goat, and cow manure), bokashi manure, and a control, coded as LivManure, BokManure and Control, respectively. Growth parameters including leaf area, number of white flowers and number of runners, as well as yield parameters such as the number and weight of strawberries were assessed from the 3rd to 10th week after transplanting, during the short rain season of 2021. Using R statistical software, linear models were fitted to datasets from both study sites and analyzed using one-way ANOVA, followed by post-hoc tests for multiple comparisons. The rigorous analysis of the Kabete and Mbooni datasets provided insightful revelations about the influence of different treatments on strawberry characteristics, and geographical disparities between the two regions. The analysis of variance (ANOVA) outcomes unveiled significant treatment effects in both sites, with F(2,69) = 62.57, p < 0.001 for Kabete and F(2,69) = 49.02, p < 0.001 for Mbooni, highlighting distinct influences of treatments on log values within each group. Post hoc analyses, including Tukey tests and bootstrap comparisons robustly validated the significant differences among the three treatments in each site, supported by p-values <0.001. Effect sizes were also employed to reinforce the findings, and planned contrasts were set to gain more power in the analysis of variance. Comparison between Kabete and Mbooni indicated a significant difference of 9.78 units, with Mbooni area exhibiting significantly higher strawberry characteristics compared to Kabete. The results showed that LivManure treatment had the highest mean in both sites, followed by BokManure and Control treatments, respectively. These findings have important implications for agriculture, and highlight the potential benefits of using LivManure treatment to improve strawberry characteristics in similar agroclimatic settings. These observations can be attributed to the beneficial effects of livestock manure on soil health, which include buffering of the soil reaction, provision of essential plant nutrients and enhancement of soil faunal activities. Balanced use of livestock manure is recommended to enhance soil macro and micronutrients, and soil reaction for improved growth and yield of strawberry.

Erosion by water is one of the most common types of soil degradation which occurs in all climatic regions and is widely considered to be a serious threat to the long-term viability of agriculture in many parts of the world. Lake Ol Bolossat in Nyandarua County, Kenya, is a high altitude lake that was formed on Rift Valley escarpment and faces the challenge of siltation due to increased soil erosion. Over the last few decades, the lake has been encroached and lake area has been overgrazed reducing the vegetation cover around the Lake. An assessment of spatial soil erosion loss was conducted using USLE model and GIS which showed that most parts of the Lake catchment have soil loss beyond tolerable levels of nine tons per year. The soil erosion range was between zero and 22, 525.5 tons per year. The land uses that were more vulnerable to soil loss are croplands, grazing lands with sparse vegetation and barelands which had soil loss ranges of 10–50 tons, 100 to 1000 tons and 500 to 22,525.5 tons per year respectively. The study recommended for immediate interventions by policy makers, researchers and development partners in curbing the soil loss problem.

In this paper, we use a discrete choice experiment conducted among pastoralists in four different semi-arid counties in Kenya characterized by different land tenure regimes to analyze how pastoralists make tradeoffs between tenure security and grazing flexibility - the so-called pastoralist paradox. Results show that there is one group of respondents who are desperate for change and seem to prefer either group or private title deeds to their current situation. A second, smaller group has strong preferences for the status quo, which could be driven by their relatively short migration distances. Concerning index-based livestock insurance, the basis risk suffered by insured pastoralists due to underprediction is high, but willingness to pay (WTP) for livestock insurance should still be high enough to ensure maximum uptake, leaving current low uptakes hard to explain. The worry about climate change is high but does not translate into increased WTP for more secure tenure or formal livestock insurance.

Range exclosures have been used as a tool to restore degraded communal grazing lands in Tigray region of Northern Ethiopia. Although there seems to be ecological evidence of success in rehabilitation of degraded rangelands in Tigray, there is unclear translation of these achievements into socio-economic benefits. It was hypothesized that this could be partly attributed to poor governance of the range exclosures occasioned by low participation and weak rules. This paper tried to characterize the exclosure governance system in Tigray Region of Northern Ethiopia to understand the key and interconnected exclosure governance elements of public participation and rules at the grass-roots level. Tanqua-Abergele located in the lowlands of Tigray was systematically selected from districts under Sustainable Land Management Programmes (SLMP). Five Tabias were selected from the district for the governance study. Data was collected from 331 surveyed households, 43 Key Informants and 72 Focus Groups. The results of binary logit regression showed that public engagement in exclosure governance was determined by gender, age, training in SLMP, Tabia and administrative role ( p < 0.05). Participation of local community during exclosure selection varied significantly with respondents’ administrative roles ( p = 0.026), age group ( p = 0.001), SLMP training ( p < 0.001), and gender ( p = 0.007). The main challenges reported to undermine sustainability of the exclosure programme were illegal grazing and encroachment of exclosures. Communities were not adequately involved in decisions on establishment, formulation of bylaws, and benefit distribution. This has led to incidences of forceful access to resources within exclosures, often resulting in conflicts among guards and community members. Institutionalizing exclosure management at village level is necessary to provide ownership and responsibility to the communities and for the sustainability of the rangeland rehabilitation programme.

Land rehabilitation through exclosures has been recognized as a promising practice in the restoration of degraded drylands. This study evaluated woody species density, diversity, cover, and biomass production from three regeneration approaches (EMTs): (1) Naturally Regenerated (ENR) exclosures, (2) exclosures with Soil and Water Conservation Structures (ECNR), and (3) those enriched with exotic and local plant species in addition to SWC structures (ECP) among which empirical evidence of comparisons are lacking for appropriate decision making of which restoration strategy to promote. Primary data were collected from a total of 72 study plots located across transects laid within exclosures and in adjacent grazing areas with similar ecological condition. Interview with 331 households and focus groups was used to further understand the effects. Regression analysis revealed that the mean difference in herbaceous and canopy cover, herbaceous and woody biomass, and woody species density and diversity of the three EMTs was statistically significantly higher than in the adjacent open grazing areas. Moreover, herbaceous biomass in ECP differed significantly from that of ECNR. The results indicated that ENR and ECP equally enhanced the selected vegetation parameters. This is predominantly attributed to the comparable responsiveness of many degraded areas to natural regeneration as they do to active regeneration approaches. Implementation of natural regeneration is suitable for immediate recruitment of strategy in terms of resources, time, and meeting objectives before decisions are made for assisted models of exclosure that require massive campaigns to construct soil and water conservation structures and huge seedling production in the dryland areas.

In Tigray, northern Ethiopia, land degradation has generally undermined the environmental goods and services (EGS) those local communities depend on for their livelihoods. Massive sustainable land management programs (SLMP) to restore degraded land have temporarily ceased to be accessible free of charge to communities because human and animal interference were seen as the main drivers of the problem. The SLMP deals with agricultural productivity and land degradation through integrated watershed and landscape management where exclosures are key components. As a result, the expected translation of restoration outcomes into meaningful economic benefits for local communities is critical to the sustainability of the program. The current research deviated from previous studies by focusing on tangible benefits extracted by local communities from exclosures. A survey to understand the actual economic impacts of exclosures on the local communities was conducted in five villages of Tanqua-Abergele district of Tigray. We interviewed 331 households, 43 key informants and five focus groups each composed of 12–16 participants. Regression analysis revealed that the role of household heads in the village, governance and distance to the nearest exclosure were significantly associated with higher contribution of exclosure to household (CEHH) income. While gender showed positive but no significant effect on CEHH income, level of education was significantly against. A binary logistic regression showed that role of household heads in the village, governance system and gender had statistically significant association with higher benefit–cost ratio (BCR). While exposure to several sustainable land management training has positive but no significant effect, education levels were significantly against BCR. Discussions revealed that exclosures brought benefits to the local communities with increased water, enhancement of plant biodiversity and recovery of degraded lands. However, local communities are not making maximum tangible benefits and the contribution to household income is minimal which could counter exclosure expansion and sustainability. Maximizing benefits through designing of new irrigation sites to utilize the increment of water, planned harvest of grass for construction and animal feed, deployment of modern bee hives inside and near exclosures and creation of opportunities to collect wild fruits remain to be crucial.

Pastoralist adaptation strategies have to address multiple, overlapping, and often inter-related processes of socio-ecological change. The present study addresses the need for inter-regional comparative studies that account for different geographic, climate, and socio-economic contexts in order to understand how pastoralists adapt to changes in livelihood conditions. The paper uses data from a unique survey study of pastoralist households in four neighbouring counties in dryland Kenya. Taking our point of departure from an empirically based classification of the livelihood strategies available to pastoralists in the Horn of Africa, the survey offers novel insights into adaptation and fodder management strategies of pastoralist individuals and households. The results show that the use of migration as a strategy is more dependent on the ability to migrate than climate conditions. This is the case in localities where a substantial part of the land is subdivided, the population density is high, and where opportunities for migration are subsequently restricted. Diversification of livelihoods as a strategy is largely defined by opportunity. Intensification through active fodder management is mainly common in areas where there has been a proliferation of managed enclosures. Climate change will test the adaptive capacity of pastoralists in the studied region, and diversification and intensification strategies of both herd composition and livelihoods can be seen as strategies for increased climate resilience.

This article presents hydro-chemical and isotopic (δ15N-, δ18O‒NO3−, δ11B) data of water samples and potential nitrate sources from the Nyando river basin, a tributary of the Lake Victoria in Kenya. The data collection involved field sampling of water samples in 23 sampling stations spatially distributed in the basin during nine seasons from July/2016 to May/2018. The hydro-chemical data was generated from the Laboratory analysis of the water samples using the ion chromatogram. Samples for nitrate isotope (δ15N-, δ18O‒NO3−) analysis were prepared via the bacterial denitrification method and analysed using Isotope Ratio Mass Spectrometer. The data, which is categorised in different land use zones and seasons, is important for understanding the spatiotemporal variation in nitrate and solute concentrations and the role of land use on the river water quality. In addition, the δ15N-, δ18O‒NO3− and δ11B values are key for elucidating nitrate pollution sources and potential biogeochemical processes for the management and control of nutrient pollution and eutrophication of the Lake Victoria. Furthermore, the dataset can be of great use in water quality models for understanding non-point pollution dynamics in tropical basins. This article is related to [1].

BackgroundEnhancing soil organic carbon storage in areas under extensive livestock grazing has become a challenge in most arid and semi-arid rangelands in Sub-Saharan Africa. In Kenya for instance, continuous unplanned grazing in community lands has led to overgrazing and degradation of the rangelands. For decades, livestock production has shaped the landscape through various management practices. Grazing can be used to increase soil organic carbon (SOC) content but intensive use of land can lead to its depletion. This study was set out to elucidate the effect of two types of grazing management under varying land cover types on mineral-associated organic carbon (MAOC) and particulate organic carbon (POC) in the soil. The study was carried out in two ranches, Mpala Research Centre (controlled grazing) and Ilmotiok Community Group Ranch (continuous grazing). The experimental design was a completely randomized block design in split-plot arrangement with three replicates. The main plots were the grazing practices; (controlled grazing and continuous grazing); and sub-plots were the land cover types: (bare ground, patches of grasses, and mosaics of trees). These treatments were randomly selected and replicated three times. Three topographical positions (mid-slope, foot slope and bottom land) were used as a blocking factor.ResultsThe interaction had no significant effect on MAOC fraction in any soil depth interval. Controlled grazed zones significantly recorded higher organic carbon content (POC= 0.887% CC SD=0.49) compared to zones under continuous grazing (POC = 0.718% CC SD=0.3). Mosaic of trees (POC =1.15% CC, SD = 0.22) recorded the highest concentration of carbon followed by patches of grass (POC = 0.87% CC, SD= 0.37) and bare ground (POC = 0.38% CC SD = 0.12) had the least.ConclusionThis study shows that grazing practices as well as land cover types have a significant effect on POC but not on MAOC. Mosaic of trees under controlled grazing has higher POC whereas bareground under continuous grazing had the least POC. Destocking should be done under continuous grazed zones to reduce further loss of POC and MAOC and allow vegetation recovery.

Drylands in Sub-Saharan Africa are subject to rapid and enduring population increase, agricultural expansion, land large-scale infrastructure developments, as well as climate change, affecting some 265 million pastoralists and agro-pastoralists. These changes are promoting a transition from traditional pastoralist ways of life characterized by seasonal mobility, towards more sedentary livelihoods based on more intensive and commercial uses of land-based resources. As part of of this ongoing transition, establishment of enclosures on pastoralist commons is emerging as a default, but highly contested, development pathway. Based on a review of the current enclosure debate across the natural, economic, and social sciences, with a geographical focus on the East African drylands, we discuss the potential and limitations of enclosures as land management tool, and propose a conceptual framework for how enclosures can act as an integral part of sustainable pastoralist land use. Such a framework constitute an important piece of the puzzle for more productively linking the urgent need of innovative ways of managing pastoralist rangelands, to the present international and national commitments to restoration of degraded lands.