Semi-arid Kenya Research Articles

Effect of Water Conservation Technologies on Growth and Yield of Pearl Millet with Green Gram Intercrop in Semi-Arid Kenya

Effect of Water Conservation Technologies on Growth and Yield of Pearl Millet with Green Gram Intercrop in Semi-Arid Kenya

Forage yields and quality of Cenchrus ciliaris and Panicum maximum ecotypes under varied harvest intervals in a semi-arid environment in Kenya

Abstract. Kisambo BK, Wasonga OV, Kipchirchir OK, Karuku GN, Kirwa EC. 2023. Forage yields and quality of Cenchrus ciliaris and Panicum maximum ecotypes under varied harvest intervals in a semi-arid environment in Kenya. Intl J Trop Drylands 7: 102-111. Livestock production in Kenya typically relies on native pastures for nutrition and efforts are ongoing to develop varieties adapted to semi-arid conditions. A field experiment was conducted in a semi-arid environment to evaluate harvest intervals’ influence on the yield and nutritional attributes of selected grass ecotypes of two native grasses used in reseeding and fodder production. The grasses included buffel grass Cenchrus ciliaris Kilifi (KLF), C. ciliaris Magadi (MGD), Guinea grass Panicum maximum Isinya (ISY) and P. maximum Taveta (TVT). They were planted in a randomized-complete block design in a split-plot arrangement and maintained under rain-fed conditions. Forage harvests were performed at 3 harvest intervals i.e., 14, 28 and 84 days, simulating different utilization regimes in semi-arid Kenya. Biomass yield, forage accumulation and quality of the grasses were determined. The highest yields were obtained at 28-day harvest intervals and were 74% higher than the 14-day interval, although almost similar to the 84-day interval harvests. Forage accumulation rates varied significantly (p <0.005) between ecotypes and harvesting intervals. Crude Protein (CP) declined significantly with maturity, from a mean of 11.67% for the 14-day harvesting interval to 5.22% at the end of the season and varied among treatments. In Vitro Dry Matter Digestibility (IVDMD) increased with increasing harvest interval. However, fiber components-Nutrient Detergent Fiber (NDF), Acid Detergent Fiber (ADF) and Acid Detergent Lignin (ADL) increased with plant age. Harvest intervals had a significant (p <0.05) influence on the yield and qualitative attributes of the grass ecotypes. C. ciliaris ecotype MGD and P. maximum ecotype TVT are viable options for further performance evaluation in semi-arid environments as efforts to develop new range fodder varieties are accelerated.

MODELLING OF POTATO CROP WATER PRODUCTIVITY AND YIELD RESPONSE UNDER SUBSURFACE DRIP IRRIGATION SYSTEM

The need for increased food production by applying low water quantity is pausing more challenges to farmers. The production of Irish Potatoes in Kenya in arid and semi-arid areas is challenging for most farmers due to low yields. The purpose of the study was to simulate potato crop water productivity. A field experiment was conducted at Egerton University during the 2021-2022 dry season. The effect of deficit subsurface drip irrigation allied with superabsorbent polymer soil amendment on growth parameters and yield of potatoes was evaluated. Twelve treatments composed of three water application levels 70%IL, 85%IL,100%IL and four super absorbent polymer (SAP) application rates No SAP, 6 kg/ha, 10 kg/ha,and 14kg/ha laid in factorial experimental design were applied in December 2021 to May 2022 season. Irrigation was undertaken when the allowable water depletion reached 50%. The AquaCrop model was utilised to predict soil water content, biomass, canopy cover, dry yield, and water productivity (WP). The 100% water application level with 0kg/ha SAP was used in model calibration, whereas the remaining treatments were used to validate the model. The model simulated results compared with observed canopy cover, biomass and WP produced a good performance fit with R2 range of 0.86 to 0.98, root mean square error (RMSE) of 10.6%, NSE of 0.9, and Wilmot's degree of agreement of 0.98. However, the model underestimated the water content due to the application of SAP in the soil. Because the SAP improved soil characteristics relevant for water holding capacity without changing the physical texture and structure of the soil. The findings indicated that the combined effect of SAP and subsurface drip resulted in increased yield in deficit water application. The calibrated model was successfully applied in simulating WP and yield. The calibrated AquaCrop model can be applied in planning, operation and management of potato-irrigated farms that will lead to improved water productivity and yield in water constrained areas like semi-arid Kenya.

Do farmers use climate information in adaptation decisions? case of smallholders in semi-arid Kenya

Integration of climate information in farm-level adaptation decision is crucial to manage climate change induced risks. The Government of Kenya is mandated to manage and disseminate climate information to enhance adaptation to climate change. However, the use of climate information on farm-level adaptation has not been explored. The purpose of this study was to: identify the climate information accessed by farmers, establish the association between using climate information and the adaptation strategies adopted, examine the factors influencing adaptation decisions, find out how climate information were used and the benefits and constraints of using the information . Data was collected from 432 households randomly selected from semi-arid areas in Machakos, Makueni and Kitui counties. The Multivariate probit model was used to analyse data. The results showed that farmers accessed short and medium-term forecasts; decadal forecasts and agrometeorological advisories. There was a significant association between using climate information and the climate change adaptation strategies adopted by the farmers. Demographic, socio-economic and institutional factors significantly influenced farmers’ adaptation decisions. Farmers used the climate information for tactical, short-term farm operations. Benefits of using climate information were manifested in reduced crop loss, increased yield and farm revenue. However, farmers’ use of climate information was constraint by economic and technical factors. The study recommends that the Government enforces policies that empowers farmers to access the requisite farm inputs and facilitate the provision of agrometeorological advisories to increase local-level utility of climate information. The Government should formulate and implement policies that strengthen the provision of timely, simplified and adequately actionable climate information that suit farmers‘ climate change adaptation needs.

Striving to be resilient: the role of crop-poultry integrated system as a climate change adaptation strategy in semiarid eastern Kenya

Climate change continues to pose significant challenges to food security and livelihoods of smallholder farmers specifically in semi-arid regions. One approach that holds prospects for climate risk management is climate-smart agriculture (CSA). CSA has concentrated on crop practices with little attention to livestock especially indigenous (village) chickens as a potential practice that can be combined with crop agriculture. This study considers the adoption of three CSA practices: improved maize seeds (IS), soil management (SM), indigenous chicken (IC) enterprise and their various combinations. Using survey data collected from 300 farming households in semiarid Kenya, we estimate the impact of integrated crop-poultry system adoption on food security and farm income using multinomial endogenous treatment effect models. Robustness checks are conducted using alternative identification strategies. Results show that, generally, the adoption of IS, SM, IC and their combinations reduces the number of months without enough food and increases farm income. When we consider the magnitude of the impacts, interesting results emerge when a combination of the CSA practices are considered. The highest impact is observed with the joint adoption of SM & IC and IS &IC. Broadly, the empirical findings suggest that integrated systems (in our case crop-poultry integration), deserve both policy and research attention as they provide synergistic benefits that improve climate resilience and household welfare.

Effect of Tillage Method and Mulch Application on Growth and Yield of Green Gram in Semiarid Kenya

Conservation tillage is regarded as the best practice for crop production in drylands. However, their effect on the green gram (Vigna radiata (L) Wilczek) has not been much documented in ASALs of Kenya. A field study was conducted during the 2018-2019 short rains with the aim of evaluating the effect of tillage methods and mulch application on the growth and yield of two green gram varieties in Katumani and Mwea. A randomized complete block design (RCBD) with a split-slit plot arrangement and three replicates was used. The main plots were tillage methods zero tillage (ZT), furrow-ridge (FR), and conventional tillage (CT). Subplots were mulched plots with plant residue (3 t·ha−1) and plots without mulch applied (0 t·ha−1) and in the sub-subplots were two green gram varieties (N26 and KS20). Data was collected on plant height, number of primary branches, root biomass, shoot biomass, number of pods per plant, number of seeds per pod, 1000 seed weight, grain weight (t·ha1), and harvest index. Data was subjected to the general analysis of variance using GenStat 15th statistical software. Mean separation was calculated using the least significant difference LSD at a 5% probability level. Results showed that tillage methods and mulch application significantly affected growth, yield, and yield component. Furrow-ridge recorded superior effects ahead of zero tillage and conventional tillage. Mulch application had significant effects on growth, yield, and yield component. Variety N26 under the treatment of furrow-ridge mulched with 3 t·ha−1 had a greater number of branches, plant height, yield, and yield components in both experiment sites. The application of mulch had a positive impact on growth, yield, and yield component. Furrow-ridge and zero tillage with mulch emerged to be the most efficient techniques for better green gram yield in Katumani and Mwea. This can be recommended for increased crop production in areas that receive insufficient rainfall.

Gender in adoption of improved pigeon peas and its effect on food security Kenya

ABSTRACT This paper examines the adoption of improved pigeon peas in female-headed households (FHHs) and male-headed households (MHHs) in semi-arid Kenya and its effect on yield as a proxy for household food security. Cross-sectional data were obtained from 450 households through a multi-stage sampling approach. We applied the endogenous switching regression model to establish the determinants of adoption decision and their effects on yield. Results showed that adoption increased crop yield. The adopting MHHs had significantly higher yield compared with the FHHs. The difference in yield was explained by both observed and unobserved characteristics in gender of the household head.

Reducing Climate Risks by Improving Food Production and Value Chains: A Case of Sandy Soils in Semi-arid Kenya

Due to climate change and variability, extreme weather events are becoming more frequent worldwide, causing significant reductions in agricultural production and food security. The livelihoods of smallholder farmers, especially those eking out a living by farming on sandy soils, are particularly affected. We examined this issue using the case of Makueni County, a semi-arid area with sandy soils in south-eastern Kenya. Using survey data from 202 households, we examined extreme weather events affecting smallholder farmers and current management strategies used to mitigate the consequences. We then performed field experiments to assess potential gains of implementing sub-surface water retention technology (SWRT) in the region. Finally, we held group discussions with stakeholders in food value chains (FVC) to identify ways of managing climate risks to smallholder farmers. Analysis of the survey data showed that 199 of 202 farmers surveyed had experienced an extreme event associated with climate change and variability during the previous five years. Of these 199 farmers, 161 reported having changed their farming practices to adapt, especially to drought (70%) and increased temperature (22%). Common adaptation practices included early planting, reducing the area under cultivation, and water harvesting. In the field experiments, using SWRT resulted in a 50, 100, 150, and 170% increase in maize grain yield, cob numbers, cob weight, and maize stover biomass, respectively, compared with the control (without SWRT). Stakeholder group discussions along the FVC demonstrated a need for synergy among actors to mitigate climate risks caused by extreme weather events. These findings suggest that diversification of management strategies at farm level, combined with external inputs (new technologies, improved seeds, etc.) and services (credit access, learning from peers and professionals), will be instrumental in reducing future climate risks to smallholder farmers. Improving access to viable markets and fostering mutually beneficial linkages with post-harvest processors would add value to farm produce, thus further increasing income and the capacity of smallholder farmers to manage climate risks.

Coping with drought: Narratives from smallholder farmers in semi-arid Kenya

Globally, drought impacts more people than any other natural hazard. However, drought is also the most complex natural hazard, and its impacts are not evenly distributed across the landscape or among human populations. Just as the impacts of drought vary, so do the coping strategies used by people during drought. The research to-date on drought coping strategies in Sub-Saharan Africa are highly quantitative, focused on top-down interventions, and do not emphasize individual perceptions, experience, and autonomous decision-making when coping with drought. This paper aims to fill these gaps by examining the human experience of coping with drought through narratives from farmers in Burat and Kinna, Isiolo County, Kenya. This paper highlights (1) their perceived impacts of drought, and (2) the various coping strategies used. A total of 83 interviews were conducted in 20 households. Results found that the perceived impacts of drought were decreased agricultural productivity, livestock hunger, death, and relocation, a lack of water in rivers, human hunger and disease, and violent conflict. The strategies for coping with drought included changing agricultural practices, adopting irrigation, relying on aid, charcoal burning, casual labor, livelihood diversification, and others. Importantly, these coping strategies can be classified into four categories: livelihood diversification, longer-term livelihood strategies, short-term coping activities, and erosive coping strategies. This research contributes to the effort to better document and understand farmers’ perceptions and strategies to cope with drought through qualitative research methods and from the perspective of the individual smallholder farmer, which is important for making context-specific policy and project recommendations aimed at smallholder farmers.

Density-dependent maize (Zea mays L.) yield increase in trade-off in reproductive allocation and water use under ridge-furrow plastic-mulching

• Maize yield responses to increasing planting densities were studied in RFM system. • Individual yield declined while population one increased first and then decreased. • This difference resulted from improved soil water availability as affected by RFM. • Optimal density had better trade-off between reproductive and vegetative growth. • Allometric R–V relationship explained density-dependent yield formation under RFM. The law of constant final yield and allometric theory have been seldom used to explore density-dependent yield formation and water use in rainfed farming systems, particularly in ridge-furrow mulching (RFM) system of maize. A two-year RFM field experiment was conducted using maize variety Yuyuan7879 in semiarid Kenya from 2015 to 2016, with four planting densities: 5.2 × 10 4 (D52, conventional density), 6.0 × 10 4 (D60), 6.9 × 10 4 (D69) and 8.5 × 10 4 (D85) plants per hectare. The grain yield and aboveground biomass per plant were significantly decreased with increasing density across two growing seasons. However, the population grain yield significantly was increased from D52 to D60 (from 3395.1–4471.7 kg ha −1 ) but declined significantly from D60 to D69 and D85 (p < 0.05) in 2015 and 2016, respectively. Meanwhile, the population aboveground biomass was significantly promoted from D52 to D60 (p < 0.05) and then remained relatively stable in D69 and D85, achieving a state of constant final yield. Under the improved soil storage, the RFM system raised the rational planting density from conventional D52 to D60 with regard to population yield. Water use efficiency for population yield (WUE G ) was the highest at D52 and D60, followed by D69, and the lowest at D85. However, the WUE for the aboveground biomass (WUE A ) was significantly lower in D52 than D60 and D85. Principal component analysis suggested that the population grain yield and WUE G were significantly positively associated with the reproductive allocation and leaf growth. This result was further affirmed by the allometric relationship between leaf biomass and body size, since the allometric exponent (<1) was raised with density. Allometric relationship between reproductive and vegetative mass demonstrated that the D60 treatment achieved a relatively balanced allocation of photosynthetic products into reproductive organs in comparison with other treatments. The RFM application significantly improved the availability of soil water, and the rational planting density of maize for better yield and WUE G . Thus, this phenomenon mechanically resulted from relatively better trade-offs between reproductive and vegetative growth, together with moderately increased leaf growth.

Plant residue mulch increases measured and modelled soil moisture content in the effective root zone of maize in semi-arid Kenya

Difficulties in efficient utilization of seasonal precipitation cause limitations in yields and even total crop failure on rainfed farms in semi-arid East Africa. The objective of the present study was to find out if covering the soil with plant residue mulch at a semi-arid site could retain water in the soil between precipitation events and build dry spell resilience by reducing soil water evaporation and increasing infiltration to deeper soil. Covering soil with plant residue mulch was studied at a smallholder farm in semi-arid Kenya by continuously measuring volumetric soil moisture content with soil sensors at multiple depths in bare soil and in maize (Zea mays L.) plant residue mulched soil. A physically based one-dimensional soil moisture model was calibrated and used to estimate the effect of plant residue mulch on soil moisture over a two-year period (multiple growing seasons). The modelled multiyear time series provides an estimate of the effect residue mulches of different thicknesses have on soil moisture over time. The simple soil moisture model was able to estimate soil moisture in the effective root zone of maize. By comparing measured data from mulched and uncovered soil and by model prediction, it was demonstrated that maize residue mulch conserved soil moisture over time in the effective root zone of maize compared to bare soil. During the two-year period mulching increased the total amount of days when measured relative soil moisture (s) exceeded water stress limit of maize (s*) by 24%–46%. Moisture accumulated in the mulched profile, especially in the deeper layers of the effective root zone. Calculations indicated that further increasing mulch thickness (δm) from 1 to 3 cm would have increased the total days when s >s* 59%. Furthermore, increasing δm from 3 to 5 cm would have resulted in 25% increase in total days when s >s*. According to our calculations mulching (δm > 1 cm) could have maintained s >s* throughout a 19 days dry spell that occurred during the measurement period. The demonstrated moisture conserving effect of mulch increases with δm, but availability of plant residue may set limits on mulch application rates. The results suggest that maize residue mulching is as an accessible and feasible method for conserving soil moisture in the effective root zone in dryland smallholder systems in East Africa.

Gender Analysis of Smallholder Farmers’ Adaptive Capacity to Drought in Semi-arid Kenya

Gender Analysis of Smallholder Farmers’ Adaptive Capacity to Drought in Semi-arid Kenya

Water productivity and its allometric mechanism in mulching cultivated maize (Zea mays L.) in semiarid Kenya

Allometry is extensively used to describe the scaling relationship between individual size and metabolite allocation. Micro-field rain-harvesting system can improve soil water availability and thus alter the allocation of individual biomass among organs. Yet the eco-physiological mechanism based on allometric scaling theory has been little investigated under various mulching conditions. A field experiment was conducted using maize variety Yuyuan7879 in Juja, Kenya for two growing seasons (cross-year) from 2015 to 2016, and from 2016 to 2017 respectively. Four treatments were designed as ridge-furrow mulching (RFM) with black plastic mulching (RFMB), transparent plastic mulching (RFMT), grass straw mulching (RFMG) and conventional flat planting (CK). We found that RFMB, RFMT and RFMG significantly increased grain yield by 106%, 109% and 32% in 2015, and 101%, 96% and 30% in 2016 respectively, in comparison with CK. Mulching treatments improved soil temperature and moisture and significantly increased crop water productivity (CWP). Mulching treatments drastically changed the allometric relationship between metabolic rate (leaf biomass) and individual size (lgy = αlgx + lgβ), and optimized the size-dependent reproductive allocation. In the relationship between leaf biomass (y-axis) vs aboveground biomass (x-axis), mulching treatments significantly declined the value of α (α < 1; P < 0.01), suggesting that less photosynthetic product was allocated in leaves in mulching treatments than in CK. As for the allometric relationship between grain yield and aboveground biomass, the α was generally significantly more than 1 in RFMB and RFMT, and significantly less than 1 in RFMG and CK, demonstrating that more photosynthates were allocated to reproductive growth under plastic mulching. Also, the variation of allometric relationship between reproductive and vegetative biomass provided further evidence that plastic mulching facilitated substance transportation from vegetative to reproductive organs. In conclusion, plastic mulching significantly improved soil hydrothermal condition, increased individual reproductive allocation and ultimately improved grain yield and CWP at population level.

GIS ANALYSIS OF PHYSICAL ACCESSIBILITY TO FOOD MARKETS IN THARAKA REGION OF KENYA

In semi-arid rural Kenya, most households travel long distances to access food markets. This has negative effects on food consumption and the use of market facilities. Over70 % of farmers in Tharaka Constituency lack access to formal markets often relying on contracted middlemen who buy at farm gate for traders in major urban centres. Studies on intra-variation in accessibility to market services remains scanty, yet market purchases account for most food consumed across urban and rural areas. Distance defines accessibility and performance of market facilities in most areas where food insecurity and malnutrition are common. This study used Geographic Information Systems (GIS) to measure physical accessibility to open air markets within semi-arid Tharaka, a constituency where vulnerability to acute food shortage is comparatively high. Normative, administrative and geospatial datasets were used in the analysis. Results showed that geographic accessibility to local market centres vary spatially across the villages. In terms of market accessibility, 40.4% of the total population live in areas with high inaccessibility risks while 36.1% are found in places with low inaccessibility risks and only 23.5% of the population exists in areas with moderate inaccessibility risks. This means a large proportion of deprived population live in villages within high to very high inaccessibility risk areas. This spatial inequity has implications on household food security and explains the chronic problems of hunger and malnutrition experienced in the area. Therefore, markets within high inaccessibility risk areas should be upgraded and infrastructure thereof improved to enable food mobility across these areas.

Integrated crop-livestock farming offers a solution to soil fertility mining in semi-arid Kenya: evidence from Marsabit County

ABSTRACT Low-input agriculture is prevalent in sub-Saharan Africa but it cannot deliver future food security. Soil nutrients are being mined by small-scale farmers who continue to remove large quantities of nutrients from their soils without using sufficient manure or fertilizer inputs to maintain soil fertility. Declining soil fertility must be addressed in order to achieve sustainable intensification. A large increase in nutrient inputs is seen as a requirement but small-scale farmers face severe constraints in obtaining supplies of mineral fertilizer. Better use of available livestock manure is a possible solution. We present here a case study from Marsabit County in the largest, most arid, and least developed region of Kenya. Evidence was gathered from field studies at four locations during 2016 and 2017 combined with a farmer survey. We show that a typical smallholder farm can achieve satisfactory yields and an acceptable nitrogen balance through better use of available livestock manure. An acceptable balance can also be achieved for phosphorus, however, there is a deficit for potassium. This case study demonstrates that an integrated crop-livestock farming system offers a potential solution to soil nutrient mining and can provide a pathway to sustainable intensification for small-scale farmers in a challenging semi-arid environment.

Simulating Small-Scale Agricultural Adaptation Decisions in Response to Drought Risk: An Empirical Agent-Based Model for Semi-Arid Kenya

In Eastern Africa, increasing climate variability and changing socioeconomic conditions are exacerbating the frequency and intensity of drought disasters. Droughts pose a severe threat to food security in this region, which is characterized by a large dependency on smallholder rain-fed agriculture and a low level of technological development in the food production systems. Future drought risk will be determined by the adaptation choices made by farmers, yet few drought risk models … incorporate adaptive behavior in the estimation of drought risk. Here, we present an innovative dynamic drought risk adaptation model, ADOPT, to evaluate the factors that influence adaptation decisions and the subsequent adoption of measures, and how this affects drought risk for agricultural production. ADOPT combines socio-hydrological and agent-based modeling approaches by coupling the FAO crop model AquacropOS with a behavioral model capable of simulating different adaptive behavioral theories. In this paper, we compare the protection motivation theory, which describes bounded rationality, with a business-as-usual and an economic rational adaptive behavior. The inclusion of these scenarios serves to evaluate and compare the effect of different assumptions about adaptive behavior on the evolution of drought risk over time. Applied to a semi-arid case in Kenya, ADOPT is parameterized using field data collected from 250 households in the Kitui region and discussions with local decision-makers. The results show that estimations of drought risk and the need for emergency food aid can be improved using an agent-based approach: we show that ignoring individual household characteristics leads to an underestimation of food-aid needs. Moreover, we show that the bounded rational scenario is better able to reflect historic food security, poverty levels, and crop yields. Thus, we demonstrate that the reality of complex human adaptation decisions can best be described assuming bounded rational adaptive behavior; furthermore, an agent-based approach and the choice of adaptation theory matter when quantifying risk and estimating emergency aid needs.

Fully biodegradable film to boost rainfed maize (Zea mays L.) production in semiarid Kenya: An environmentally friendly perspective

Abstract Conventional polyethylene plastic film mulching has been widely used, but its subsequent plastic residue pollution received widespread concern. Fully biodegradable film mulching is viewed as a potential substitution solution, however, it is generally thought not to be efficient as conventional plastic film mulching in field productivity and economic harvest. A two-year field experiment using a newly produced fully biodegradable film was conducted in semiarid Kenya in 2016 and 2017 respectively. Five treatments were designed as: 1) ridge-furrow mulching (RFM) with transparent plastic film (RFMT), 2) RFM with fully biodegradable film (RFMD), 3) RFM with black plastic film (RFMB), 4) RFM with grass straw (RFMG) and 5) traditional flat planting without mulching (FP) as CK. We found that RFMD achieved the similar evaporation-restricted, yield-increased and water-saving effectiveness as RFMT and RFMB did across two growing seasons. The RFMD lowered evaporation by 58.1 mm, while increasing grain yield by 70.16 %, above-ground biomass by 77.7 % and water use efficiency (in reference to grain yield) (WUEG) by 131.8 % in comparison with CK respectively. Furthermore, RFMD increased net economic income by 49.8 % in 2016 and 42.0 % in 2017 respectively relative to CK, as RFMT and RFMB did. It is noted that the degradable film used in this experiment is a non-polyethylene material and still can be maintained for 60 days in a fine physical state. Also, average soil temperature was significantly elevated by 1.6 °C in 2016 and 1.8 °C in 2017 in RFMD respectively, in comparison with CK, which was beneficial to crop growth and grain filling particularly in relatively cool long rainy season. Considering residual film pollution, the biodegradable film showed reliable advantages in environmental friendliness and field productivity. Therefore, it might be a promising farming solution to boost rainfed maize production and environmental sustainability in east African Plateau.

Cross-scale relationships between social capital and women's participation in decision-making on the farm: A multilevel study in semi-arid Kenya

Social capital develops through relations between people and groups within community social networks. Women in smallholder agrarian communities often draw on social capital to influence their intra-household bargaining positions, with significant implications for their resource access. However, the extent to which women use different types of social capital to increase their participation in agricultural decision-making remain understudied. This research examines the relationships between women's participation in agricultural decision-making and bonding, bridging, and linking social capital and how broader contextual factors can interact with the pathways through which social capital functions in rural semi-arid Kenya. In 2014, we collected and analyzed quantitative and qualitative data: household (N = 206) and community (n = 127) surveys, key informant interviews (n = 77), twelve focus group discussions, and eight community meetings. Results indicate that women draw on bridging social capital to increase the diversity of their information and training sources. We found that women's participation in decision-making has a positive association with bonding social capital and a negative association with linking social capital. Multilevel analysis reveals cross-scale interactions between poverty prevalence and social capital on women's decision-making participation. Findings suggest that advances in regional development have the potential to amplify the stock and usage of social capital for women's empowerment in smallholder agrarian systems.

Dual plastic film and straw mulching boosts wheat productivity and soil quality under the El Nino in semiarid Kenya

The extreme climate events such as El Nino seriously threaten crop production and agro-ecological sustainability because of the aggravated environmental stresses worldwide, particularly in sub-Saharan Africa. To address this issue, we investigated the effects of dual plastic film and straw mulching in ridge-furrow (RF) system on wheat productivity, soil carbon and nitrogen stocks in a semiarid area in Kenya from 2015 to 2017. The experimental site represents a typical semiarid continental monsoon climate, and soil type is chromic vertisols. Field experiment with randomized block design consisted of six RF treatments as follows: 1) dual black plastic film and straw mulching (RFbS), 2) dual transparent plastic film and straw mulching (RFtS), 3) sole black plastic film mulching (RFb), 4) sole transparent plastic mulching RF (RFt), 5) sole straw mulching (RFS) and 6) no mulching (CK). The results indicated that seasonal dynamics of rainfall and air temperature fit in with the weather type of El Nino over four growing seasons. RFbS, RFtS, RFb and RFt significantly increased soil water storage (SWS), topsoil temperature, aboveground biomass, grain yield and water use efficiency across four growing seasons (p < 0.05) as compared with CK. Among all the treatments, RFbS and RFtS achieved the greatest SWS, AgB, grain yield and WUE, owing to improved soil hydro-thermal status in both treatments. Critically, RFbS and RFtS significantly improved soil organic carbon and total nitrogen, soil bulk density and the C:N ratio following four growing seasons, comparing with other treatments (p < 0.05). Besides, RFbS and RFtS gave the highest economic returns among all treatments. For the first time, we found that dual plastic film and straw mulching could serve as a sustainable land management to boost wheat productivity and improve soil quality under El Nino in semiarid areas of SSA.

Rainfall variability, soil heterogeneity, and role of trees in influencing maize productivity—the case from an on-station agroforestry experiment in semi-arid Kenya

ABSTRACTGiven that crop yield in smallholder farms is influenced by rainfall and soil variability, farmers have designed strategies to address water deficit and enhance productivity, including adopting agroforestry. However, there is insufficient evidence demonstrating the combined effect of rainfall variability, soil heterogeneity and agroforestry treatment on maize productivity in semi-arid Kenya. We evaluated performance of agroforestry trees (Vachellia seyal, V. xanthophloea, Cordia africana, Faidherbia albida and Grevillea robusta) in monoculture and mixed-species treatments in a long-term experiment in Kiambu, Kenya, and their influence on maize intercrop. The trial was laid out in Randomized Complete Block Design having a mix of Cambisol and Vertisol soils. Tree growth and phenology was monitored monthly while maize yield assessed in four cropping seasons. Growth was higher in 2014 for all species compared to other years (P < .001). Cordia africana and F. albida in mixed stand and Cambisols exceeded those in monoculture and Vertisols (P < .001). Maize yield grown under C. africana and mixed-species during 2015/16 season was 54% and 44% higher than the control with corresponding canopy transmittance values of 18% and 24% respectively. Maize yield was highest in 2013/14 season (4.2 t ha−1) with rainfall distribution affecting productivity in 2014/15 season whereby 74% of rainfall was received in 1 month resulting in crop failure. These findings demonstrate the reality of climate (rainfall) variability, and the influence of soil properties heterogeneity while supporting call for mixed-species and encouraging efforts aimed at forecasting rainfall patterns as this affects farming operations.