Nitrogen use in maize-pigeonpea intercrop in semi-arid conditions of Kenya

Abstract

A field experiment was conducted at Jomo Kenyatta University of Agriculture and Technology between 2001 and 2002 to determine nitrogen (N) use in maize-pigeonpea intercrop system. Pigeonpea included long duration (erect - and semi-erect) and medium duration types either intercropped with maize (Katumani composite), or as sole crop. Maize, sorghum and cotton, were evaluated as reference crops for biologically fixed N. Plant total nitrogen and soil mineral N at key phenological stages were determined. Maize and sorghum accumulated more shoot dry, mass compared to pigeonpea, hence were unsuitable as reference crops. Cotton had similar growth characteristics and phenological development to the long duration pigeonpea varieties but was unsuitable as reference crop for the medium duration pigeonpea. Long duration cultivars had the highest plant N uptake and contributed high amount of N through litter fall and biological fixation compared to medium duration. Soil mineral N increased over time. Long duration erect pigeonpea had the highest total dry matter and grain yield while medium duration pigeonpea had the lowest. Maize grain yield and total N uptake in subsequent season after pigeonpea was higher in plots that were previously planted with pigeonpea than those planted continuously with maize.