Comparative Effects of Cowpea and Soybean Genotypes on N2 - Fixation and N-Balance in Sokoto Dry Sub-Humid Agro-Ecological Zone of Nigeria.

A field trial was conducted to asses N2 - fixation and N balance in five cultivars each of soybean (TGX 1945 – 1F, TGX 1951 – 4F, TGX 36 – 54KT, TGX 1951 – 3F and TGX 1935 – 3F) and cowpea (IT88D-867-11, IT89KD-288, IT90K-l372-1-2, IT90K – 82-2 and Bahaushe (local). The legume genotypes and reference millet crop (ZM – 01- 58) were planted in a randomized complete block design with three replications. N difference method and the difference between N2 - fixed and N exported in grain at harvest were used to estimate N2 - fixed and N balance respectively. The biomass yield (2.9 to 5.23 t ha-1) in cowpea cultivars were significantly (