Evaluation of Nitrogen Fixation using 15N Dilution Methods and Economy of a Maize-tepary Bean Intercrop Farming System in Semi-arid SE-Kenya

摘要: Tepary bean has become popular among poor small-scale farmers in semi-arid Kenya, where it is intercropped with maize. This study aimed at i) evaluating the N-economy of maize/tepary intercrop versus sole crop using natural abundance and 15N enriched fertilizer methods, ii) assessing contribution fixed N2 by tepary to total N balance intercrops cropping systems assessed from harvested seed residues. Experiments were carried out during short rains 2001/2002 long 2003 Kenya Agriculture Research Institute (KARI) Kiboko, Kenya. Randomised block design was used one devoted (–N), other labelled (+N), replicated 4 times. Above ground biomass determined crops or (–N +N). received 53–69% its supply N2-fixation slightly affected intercropping application. greenhouse experiment lower (36–66%) than field more supply. Budgets for estimated based on above-ground yields, return residues, input N. 59 kg ha-1 plots receiving no fertilizer, 73 as urea. Corresponding fixation high (87 82 ha-1, respectively), but this advantage outweighed greater land use efficiency