Contribution of Promiscuous Soybean （Glycine max L.） to Upland Rice-based Cropping Systems in West Africa

A two-year on-farm study was carried out at Eglime in the moist savanna （MS） and Ouake in the dry savanna （DS） of Benin to evaluate the contribution of inoculation of dual-purpose soybean varieties to grain yield of upland NERICA rice fertilized with low N level. In 2005, four dual-purpose, promiscuous soybean varieties （cv. TGx1440-IE; TG×1448-2E; TG×1019-2EB; and TG×1844-18E）, and a popular improved variety （cv. Jupiter） were sown in 12 farmer fields with and without Bradyrhizobium japonicum inoculation. There was also land which was left fallow that acted as the control. In 2006, upland interspecific rice （NERICA 1） was sown in all the plots and supplied with 15 kg N haL. Dry matter yield, N accumulation, and net N-balance were significantly enhanced by over 40% with inoculation of cv. TG× 1844-18E than non-inoculation in the DS in comparison to other cultivars. There were no significant effects of inoculation of previous soybean cultivars on soybean grain yield and on the succeeding NERICA rice yield. Averaged over inoculation, previous cv. TG× 1019-2EB plots supplied with only 15 kg N hal gave the highest grain yield, more than twice the yield of control plots in the DS, possibly because of significant production of higher tillers, panicles and harvest index than the other cultivars; and it could be recommended for upland rice-based system for NERICA production.

Contribution of Promiscuous Soybean （Glycine max L.） to Upland Rice-based Cropping Systems in West Africa

Bradyrhizobium, crop rotation, degraded savanna, promiscuous soybean, NERICA rice.