Undersowing maize with Sesbania sesban in Southern Malawi: 1. Tree growth, biomass yields and maize responses to N source at three landscape positions
1998
Phiri, A.D.K. | Kanyama-Phiri, G.Y. | Snapp, S.S.
Many soils of Sub-Saharan Africa are depleted of soil organic matter, an important source for organic nitrogen and phosphorus. This organic matter depletion arises largely from continuous maize cultivation on small land holdings. The situation is usually aggravated by high human population pressure which forces farmers to cultivate on steep and fragile slopes that are vulnerable to runoff and soil erosion. The objectives of this study were [1] to determine growth, survival, biomass and quality of Sesbania at three landscape positions, and [2] to assess agronomic yields of maize in response to nitrogen source and landscape position. An on-farm experiment consisted of three landscape positions combined factorially with three nitrogen sources in a randomized complete block design involving 40 farmers who served as blocks (replicates). The three landscape positions were: valley bottom (0 - 12%), dambo margins (0 - 12%), and steep slopes (12%). Sesbania sesban and CAN served as organic and inorganic N sources, respectively, while the control treatment received no external source of N. Plant survival, number of primary branches per plant, stem diameter, leafy and woody dry matter yields and stack volume of Sesbania were significantly different at the three landscape positions, as was maize grain yield. Maize grain yield from the inorganic source of N was significantly higher (P0.05) than maize yield from the control source though not significantly different from the organic source. These results indicate that there is potential for tree legumes to contribute to soil fertility under relay intercropping of maize and Sesbania sesban.
Показать больше [+] Меньше [-]