Sustainable intensification of the agriculture in sub-Saharan Africa is essential to feed a growing population by increasing crop productivity and food security while preserving ecosystem services. The N2Africa initiative is contributing to the onset of this by strengthening the implementation of nitrogen fixating leguminous species in smallholder farming systems. In the project country, Tanzania, common bean (Phaseolus vulgaris) constitute a staple food and principal source of dietary protein, however, the crop is subject to substantial yield losses caused by nutrient limitations and biotic stresses. As the latter has received less attention in N2Africa, the object of this project is to identify occurring biotic stresses and the effect of cropping system or common bean cultivar (local, improved) on their severity. To address these a maize-common bean field trial at Kimashuku in the Northern Highland of Tanzania was studied throughout the long rain season, 2017. Data collection was done by in field measurements, visual scoring using standardized protocols and laboratory analysis.
At the site we scored the incidence and progression of damage done by 20 pests and 14 diseases while assessing crop light interception and development. Effect of rotation and intercropping was found to have a negligible effect on biotic stresses. Moreover, observations of severe N, P, K and Mg deficiencies suggested that nutrient limitations were a major yield gap component at the site. Maize in a cropping system with the local common bean cultivar showed an overall higher performance with the rotation system scoring a land equivalent ratio of 1.64. However, a substantial yield gap of 64 to 86 percent was found in the maize crop. On basis of our findings we recommend further studies on most important biotic stresses identified at the site and on near-future practices for smallholder farmers to control these.
MSc and Bcs thesis, internship reports