Michael Kinyua

In sub‐Saharan Africa, there is growing interest in conservation agriculture practices, including reduced tillage (e.g., ripping), residue retention, and crop diversification, but their effects on soil moisture and penetration resistance in sub‐humid regions remain unclear. This study investigated the effect of ripping, residue retention, cropping systems, and fertilizer management on soil moisture, penetration resistance, and maize ( Zea mays L.) grain yield in a sub‐humid zone of western Kenya. The study was conducted in a long‐term experiment in western Kenya, using a split‐split‐split plot design with tillage in the main plot, while residue retention, cropping systems, and fertilizer application were the sub‐plots, sub‐sub‐plots, and sub‐sub‐sub‐plots, respectively. There were nine treatments and four replications. Soil moisture, penetration resistance, and maize grain yield were measured between 2023 and 2024. Residue retention resulted in significantly ( p  < 0.001) higher soil moisture (52.93–55.09 mm) in the 0‐ to 90‐cm soil depth than residue removal (25.98–28.91 mm). Maize–soybean rotation also had significantly higher ( p  < 0.001) soil moisture in the 0‐ to 90‐cm soil depth (41.42–45.08 mm) than the continuous maize (36.29–41.07 mm). The penetration resistance in the wet period ranged between 90 and 320 pounds per square inch (PSI), and between 200 and 492 PSI during the dry period. Ripping resulted in 12% higher maize grain yields than hand digging. Maize–soybean rotation had a higher ( p  < 0.001) maize grain yield (3.93 t/ha) than continuous maize system (1.57 t/ha). Nitrogen application at 90 kg N/ha in a continuous maize and 60 kg N/ha in maize–soybean rotation systems resulted in 118% and 85% higher maize grain yield, respectively, than when no nitrogen was applied. Similarly, applying phosphorous (60 kg P/ha) and potassium (60 kg K/ha) in maize–soybean rotation increased maize grain yield by 40% more than when potassium (60 kg K/ha) was applied as the only nutrient. Therefore, residue retention and ripping significantly improve soil health by enhancing moisture retention and reducing penetration resistance. Farmers in the sub‐humid western Kenya region can increase maize yields by adopting maize–soybean rotation, applying appropriate fertilizers (nitrogen, phosphorous, and potassium, each nutrient applied at the rate of 60 kg/ha), and implementing residue retention and ripping, especially under low rainfall conditions.

This study examined associations between two strip-cropping innovations, cereal–legume (Mbili-Mbili) and legume–legume (doubled-up legume, DUL), and intra-household decision-making, labor allocation, and control over production benefits among smallholder farmers in Babati, northern Tanzania. Household survey data were collected from 157 households using a multi-stage cluster sampling approach, capturing variation by gender, age groups, and household characteristics. Across technologies, households were predominantly male-headed (91.7%), with men comprising 71.3% of respondents and managing 66.9% of trial plots. Decision-making on production, marketing, and income use was predominantly led by men, with joint decision-making accounting for approximately 24–32% of income-related decisions. Women contributed a larger share of field labor across both systems, providing 17.7% more labor than men under Mbili-Mbili and 29.7% more under DUL. Economically, Mbili-Mbili was associated with higher average net benefits (US$731 ha⁻¹) and benefit–cost ratios (2.5) than DUL (US$213 ha⁻¹; BCR = 0.7). More than half of Mbili-Mbili participants (53.3%) reported modifying the trial design, compared with 18.4% of DUL participants; Mbili-Mbili farmers trained more non-project farmers on average (4.0 vs. 0.9) and allocated larger areas for expansion (0.5 vs. 0.3 ha). Exploratory analysis suggested descriptive associations between productivity and economic outcomes and selected household characteristics, including labor availability and education. Overall, Mbili-Mbili exhibited stronger economic performance but higher labor requirements, with women contributing disproportionately to field operations under both technologies. These findings highlight the need for gender-responsive design, labor-saving options, and inclusive decision-making arrangements to support equitable and sustainable adoption of diversified strip-cropping innovations.

In sub-Saharan Africa, land degradation and climate change continue to undermine agricultural productivity by reducing soil productivity and water availability. This review identifies soil and water conservation technologies successfully applied in climatically analogous regions of sub-Saharan Africa with the aim of informing effective technology transfer to Senegal, particularly Sédhiou and Tambacounda. Using K-means clustering on WorldClim bioclimatic variables, 35 comparable countries were identified, of which 17 met inclusion criteria based on data availability and ≥60% climatic similarity. Eighty-five technologies were documented and assessed for their compatibility across rainfall patterns, land gradients, and uses, with 12 emerging as consistently effective. Quantitative evidence shows that zai/tassa pits, stone bunds, and half-moons increase crop yields by 50–200%, while stone bunds and mulching reduce runoff by up to 80% and improve soil moisture retention. Terracing and tied-ridging were also linked to higher water-use efficiency, with tied-ridging increasing soil moisture by 13%. Burkina Faso, Kenya, and Malawi lead in adoption and diversity, whereas Senegal lags due to institutional gaps, limited funding, and weak extension systems. These technologies offer a readily available, evidence-based toolkit for building agricultural resilience in Senegal. However, their successful adoption requires stronger policy integration, stakeholder empowerment, cross-border learning, and private-sector engagement.

Weed seedbanks are a key driver of long‐term weed pressure and are strongly shaped by farming systems, crop rotation, and intercropping. This study evaluated the influence of organic (ORG) and conventional (CONV) farming systems, each managed under high (113–145 kg N·ha ⁻¹ , 60–83 kg P·ha ⁻¹ ) and low (31–45 kg N·ha ⁻¹ and 13–27 kg P·ha ⁻¹ ) fertilization levels, on weed seedbank density, composition, dominance, and diversity in two long‐term trials (established in 2007) at Chuka and Thika in the Central Highlands of Kenya. From 2017 to 2019, across six cropping seasons under a three‐year rotation, soil samples (0–20 cm) were collected after each season from four systems: CONV‐high, CONV‐low, ORG‐high, and ORG‐low. Weed seedbanks were quantified using the seedling emergence method. Under these conditions, weed species were identified, and density, Shannon diversity ( H ^′ ), evenness (), and principal component analysis were used to assess treatment effects. Crop rotation affected densities of all weed species, with responses dependent on crop sequence and farming system. High‐fertilization systems (ORG‐high and CONV‐high) generally supported higher total weed densities, linked to greater organic and mineral fertilizer inputs and favored high‐fertility indicator species such as Bidens pilosa , Amaranthus hybridus , Galinsoga parviflora , Stellaria media , and Commelina benghalensis . Low‐fertilization systems were associated with low‐fertility species such as Portulaca oleracea , Tagetes minuta , and Schkuhria pinnata . Dominant species included B. pilosa , G. parviflora , S. pinnata , Eleusine indica , and Setaria verticillata at Chuka and A. hybridus , B. pilosa , E. indica , and S. media at Thika, whose dominance generally declined over successive rotations. Intercropping baby corn/ Mucuna and maize/ Mucuna in ORG‐high and maize/beans and kales/Swiss chard in ORG‐low substantially reduced weed densities compared with corresponding monocrops and CONV‐low. Organic systems supported higher weed diversity and evenness ( H′ up to ∼2.0; E _H > 0.8) than CONV systems, indicating more functionally diverse, less dominance‐driven weed communities. These results highlight that integrating crop rotation, strategic intercropping, and tailored nutrient management can reduce weed seedbank build‐up and dominance of problematic species while maintaining diverse weed communities compatible with sustainable, low‐herbicide smallholder farming systems.

Capsicum (Capsicum spp.), commonly known as pepper, is highly sensitive to climate change. It is an important vegetable and spice crop cultivated worldwide for its di-verse uses, including fresh consumption. In Senegal, it plays a crucial role in both household nutrition and income generation. This study aimed to enhance hot pepper agronomic performance through adaptable, high-yielding technologies in the Tambacounda and Sedhiou regions of eastern and southern Senegal. Five treatments were tested: Absolute Control (T1), Farmer Practice (T2), Microdose fertilizer (T3), Micro-dose + Compost (T4), and Microdose + Compost + Mulching (T5). Trials were conduct-ed in 2025 at the Tambacounda Agriculture Research Center (CRAT) and Ziguinchor Agriculture Research Center, Djibelor, under both rainfed and supplemental irrigation systems, using a randomized complete block design with three replications. Results revealed significant treatment and site differences. At CRAT, T5 (Microdose + Compost + Mulching) achieved the highest yield of 31.6 t/ha, while the lowest was 10.1 t/ha. In Djibelor, overall yields were lower, not exceeding 2 t/ha across treatments. The findings demonstrate that integrated fertilization with compost and mulching substantially improves hot pepper productivity, with outcomes strongly dependent on site-specific ecological conditions. Promoting this practice as a bundled package in Tambacounda and similar agroecological zones could enhance yields and strengthen smallholder farmers’ socio-economic resilience amid changing weather.

In sub-Saharan Africa, land degradation and climate change threaten food security by reducing soil productivity and water availability. Soil and water conservation (SWC) technologies can restore soil health, enhance moisture retention, and support crop growth under adverse conditions. This review identifies SWC technologies applied in climatically similar African regions with the aim of informing adoption in Senegal, particularly in Sédhiou and Tambacounda regions. Using K-means clustering on 19 WorldClim bioclimatic variables, 35 comparable countries were identified, of which 17 met inclusion criteria based on data availability and ≥60% climatic similarity. Around 85 technologies were reviewed, including water harvesting, soil-moisture conservation, and erosion control, assessed for their compatibility across rainfall patterns, and land gradients and uses. The review highlights 12 successful technologies across Africa with high potential for cross-border transfer and upscaling in Senegal’s agroecological context. While countries such as Burkina Faso, Kenya, and Malawi lead in technology adoption and diversity, Senegal lags behind due to institutional gaps, limited funding, and weak extension systems. The findings highlight the importance of site-specific water management for improving soil conservation, biodiversity protection, climate adaptation, and food security, and emphasize the need for policy integration, stakeholder empowerment, private-sector engagement, and cross-border learning to accelerate adoption.

Zinc is an important nutrient for plant growth and development. Its availability is influenced by zinc solubilizing microbes (ZSMs). The effects of commonly promoted agronomic practices on the abundance of ZSMs are so far not well understood. In this study, conducted in 2019, we assessed the effects of farmyard manure (FYM) application, either sole or in combination with residue and/or inorganic fertilizer inputs, on ZSM community structure using 11 treatments in a long-term (17 years) integrated soil fertility management experiment located in Western Kenya. Bacterial and fungal community composition were evaluated by amplicon sequencing on an Illumina MiSeq platform. The results showed that putative ZSMs (i.e., the ZSMs generally considered to possess the zinc solubilizing capabilities) were clustered in two major clades based on either the application or no application of FYM. Sole application of FYM significantly (p < 0.05) increased the abundance of several ZSMs under a maize–Tephrosia rotation. In addition, systems with the combined application of FYM with other inputs generally showed significantly increasing trends for some ZSMs under a maize–Tephrosia rotation. Moreover, the combined application of FYM and P rather than only P significantly increased the abundance of some ZSMs under maize monocropping systems. Furthermore, as well as affecting ZSM abundance, soil chemical variables involving soil organic carbon (SOC), total N and Olsen P significantly increased with FYM application. This study indicated that management practices such as the application of FYM that increase SOC, and other soil chemical parameters, also/concomitantly increase ZSM abundance. These results imply enhanced capacities for microbial-linked zinc availability with FYM application.

Zinc is an important nutrient for plant growth and development. Its availability is influenced by zinc solubilizing microbes (ZSM). Effects of commonly promoted agronomic practices on the abundance of ZSM are so far not well understood. In this study, we assessed the effects of farmyard manure (FYM) application, either sole, or in combination with residue and/or inorganic fertilizer inputs on ZSM community structure using 11 treatments in a long-term (17 years) integrated soil fertility management experiment located in western Kenya, The study was conducted in 2019. Bacterial and fungal community composition (at 0-15 cm depth) was evaluated by amplicon sequencing on an Illumina Miseq platform following the manufacturer’s guidelines. Microbial diversity indices (Shannon, Simpson and Chao1) and statistical analyses were computed using R project packages. Putative ZSM (i.e., the ZSM generally considered to possess the zinc solubilizing capabilities) were clustered in two major clades based on either application or no application of FYM. Sole application of FYM significantly (P<0.05) increased the abundance of several ZSM under maize-tephrosia rotation. In addition, systems with combined application of FYM with other inputs generally showed significantly increasing trends for some ZSM under maize-tephrosia rotation. Moreover, combined application of FYM and P rather than P only significantly increased abundance of some ZSM under maize-monocropping systems. Furthermore, besides affecting ZSM abundance, soil chemical variables involving soil organic carbon (SOC), total N and Olsen P significantly increased with FYM application. This study indicated that management practices like application of FYM that increase SOC, and other soil chemical parameters, also/concomitantly increase ZSM abundance; implying enhanced capacities for microbial-linked zinc availability.

Zinc is an important nutrient for plant growth and development. Its availability is influenced by zinc solubilizing microbes (ZSM). Effects of commonly promoted agronomic practices on the abundance of ZSM are so far not well understood. In this study, we assessed the effects of farmyard manure (FYM) application, either sole, or in combination with residue and/or inorganic fertilizer inputs on ZSM community structure using 11 treatments in a long-term (17 years) integrated soil fertility management experiment located in western Kenya, The study was conducted in 2019. Bacterial and fungal community composition (at 0-15 cm depth) was evaluated by amplicon sequencing on an Illumina Miseq platform following the manufacturer’s guidelines. Microbial diversity indices (Shannon, Simpson and Chao1) and statistical analyses were computed using R project packages. Putative ZSM (i.e., the ZSM generally considered to possess the zinc solubilizing capabilities) were clustered in two major clades based on either application or no application of FYM. Sole application of FYM significantly (P<0.05) increased the abundance of several ZSM under maize-tephrosia rotation. In addition, systems with combined application of FYM with other inputs generally showed significantly increasing trends for some ZSM under maize-tephrosia rotation. Moreover, combined application of FYM and P rather than P only significantly increased abundance of some ZSM under maize-monocropping systems. Furthermore, besides affecting ZSM abundance, soil chemical variables involving soil organic carbon (SOC), total N and Olsen P significantly increased with FYM application. This study indicated that management practices like application of FYM that increase SOC, and other soil chemical parameters, also/concomitantly increase ZSM abundance; implying enhanced capacities for microbial-linked zinc availability.