Response of soil microfauna to tillage methods and cropping systems in humic nitosols of Eastern Kenya

Yellow passion fruit (Passiflora edulis var. flavicarpa) is emerging as an important high value horticultural crop in Kenya since its introduction five years ago. The fruit is gaining wide adoption in Mbeere Sub County due to its apparent adaptation to the hot arid conditions and tolerance to Fusarium wilt disease. However, the current production levels of the fruit are low due to poor water and nutrient management, erratic rainfall and poor agronomic practices. A study was conducted to assess the agronomic practices and main constraints among the farmers in Mbeere Sub County. A stratified random sampling procedure was used to collect data from 63 households from a total population of 170,950. Data was collected on household demographics, farm size, farming systems, planting materials, fertilizer use and irrigation types. This was carried out through personal interviews with members in each household responsible for management of passion fruit orchards using structured and semi-structured questionnaires. The results indicate that the majority of the farmers (65%) grow yellow passion as an intercrop with other food crops. Nevertheless, passion contributes to <10% of the proportion of the farm, though this proportion is expected to increase with expansion in production. Major findings indicate that the main source of planting materials were seedlings from KARLO (44%), use of Yaramillar (44%) as the preferred planting fertilizers and irrigation of crops three times per week (49%). In conclusion, yellow passion is a fruit with potential for increased adoption but more detailed studies are needed to clearly identify and understand water and nutrient management.Peter Mwirigi, Maina Mwangi, and Joseph Gweyi-Onyang

On-farm experimentation on conservation agriculture in maize-legume based cropping systems in Kenya: Water use efficiency and economic impacts

Conservation agriculture (CA) is a promising technology for controlling soil degradation, mitigating drought, increasing crop yield and reducing production costs. We hypothesized that adopting CA system would improve system productivity and efficiency, hence resulting in higher profits. To test the hypothesis, we designed a study to evaluate water use efficiency (WUE) and the economic benefits (yield and gross margins) of CA in the upper and lower midlands agro-ecological zones of eastern Kenya. Four tillage treatments, including farmers’ practice (residues removed), conventional tillage (residues removed) and two CA practices with residue retention (zero tillage and furrow–ridge), were laid out in 22 farmers’ fields where each farm was treated as a replicate. The results are based on four consecutive seasons farmer–researcher managed trials during the period 2010 and 2012. CA significantly improved crop yields after the first season of experimentation. Joint use of zero tillage and furrow–ridge provided higher WUE and yield advantage (25–34%) in the third and fourth seasons compared to the conventional practices. The lower midlands zone gave higher WUE values, which can be explained by the effects of water harvesting and retention for longer period on CA treatments. CA practices have increased income on average by 12% resulted from labour cost reduction and yield increment. Weeding costs for conventional tillage were USD 88 ha−1 compared to USD 24 ha−1 for herbicide application under CA. Practicing CA will certainly increase crop yields, WUE, generate more revenue and diversify risks during poor seasons. However, these benefits may not necessarily be earned in the first season, but will accrue in subsequent seasons