Assessment of biological Nitrogen fixing potentials of Pigeonpea genotypes intercropped with sorghum for soil fertility improvement in Southern Guinea savanna of Nigeria

In a 2-year field/laboratory study, the biological nitrogen fixing potentials of 14 newly introduced pigeonpea (Cajanus cajan (L.) Millsp.) genotypes from ICRISAT along with a local check were assessed under intercropping with sorghum (Sorghum bicolour (L.) Moench.) in Southern Guinea Savanna of Nigeria. Using sorghum as the non-fixing control and N-difference method, estimates of fixed N in pigeonpea genotypes of different maturity ratings ranged from 37.52kg/ha to 164.82kg/ha under intercropping. The average total nitrogen concentration of shoot in intercropped pigeonpea genotypes at harvest (2.83%) was higher than that for intercropped sorghum (1.83%). There were very little differences between sole cropping and intercropping in total soil N for each of the crops in the intercrop combinations in both years.. Keywords: v > Agro-Science Vol. 6 (1) 2007: pp. 33-45