Farmer-Managed Field Trials Illustrate the Benefits of Vermicompost and Biochar for Suppressing Soil Borne Diseases and Increasing Bean Yields in Western Kenya.

Common bean (Phaseolus vulgaris L.) is the main source of protein in the diet of subsistence and small-scale farmers in Western Kenya. Bean yields are very low in this region due to low soil fertility and high pest and disease pressure. Four seasons of researcher-managed trials in farmer's fields showed that use of vermicompost, biochar, fertilizer and inoculation had good potential to increase soil fertility, improve soil health and suppress soil-borne pathogens on these farms. As part of the Feed the Future - Healthy Beans Program, farmer-managed trials were initiated on 22 small farms in the long rain season of 2015 to test the potential of these amendments alone and in combination to reduce disease, increase bean yields and improve soil health. Best results were obtained by farmers where either vermicompost or fertilizer were combined with biochar amendment. Inoculation was ineffective on its own to improve yield, but was successful when supplemented with biochar, especially on acidic soils. Farmer field days were held on all participating farms and reached over 650 farmers. Field days included training on use of a household scale pyrolysis cook stove to prepare biochar for field use and effective composting methods. Additional farmer training in disease recognition and management, and making regular field visits and recording observations above and below ground helped ensure successful outcomes. Next steps are to 'pass it on' by continuing to expand networks of farmers making and effectively using organic matter inputs to improve soil health and plant productivity on their farms.