This paper reports on how green manuring trials were started, implemented and evaluated in Mangwende communal area from 1992 to 1996. The trials followed an impact study carried out in 1992 by the Farming Systems Research Unit which revealed that soil fertility technologies developed in the 1980s had not been adopted (Chikura, Mudhara, Mombeshora, Chibudu and Jeranyama, 1992). Farmers were not involved in problem identification, trial design, implementation and evaluation with the older work. Hence a Participatory Rural Appraisal exercise was conducted with farmers to identify problems and opportunities in soil fertility management. Farmers identified problems of low soil fertility and low maize yields, coupled with cash constraints for buying fertilizers. The poor soils, known as 'shapa', were associated with Striga (witchweed). Farmers, researchers and extensionists formulated and set up trials to screen legumes that could improve soil fertility, reduce Striga infestation and improve maize yields. The legumes tested were velvet bean, sunnhemp, cowpea and dolichos and were planted in either rotations or intercropping systems with maize.|Results showed that green manure crops such as velvet bean, sunnhemp and cowpea could improve soil fertility, reduce Striga incidence and subsequently increasing maize yields. Farmers preferred to use velvet bean for improving soils in rotation but not intercropped with maize because it choked the maize making it difficult to harvest the maize crop. Cowpea was preferred by farmers for Striga control because it also provided grain for food. Contributions of green manures to the soil nutrient status require investigation. Seed production by the green manures and their storage should be clarified to have a sustainable green manuring programme. The need to strengthen farmer research capabilities was identified.|

English

9906|AGRIS 9902|R98-99ANALY

Jose Juan Caballero

CIMMYT Publications Collection