Effect of mucuna intercropped with maize on soil fertility and yield of maize

Two field trials were used to evaluate the effect of mucuna (Mucuna utilis) intercropped with maize (Zea mays L.) on soil fertility and maize yield. In Experiment I, mucuna seeds were sown at 0, 2, 4, 6 and 8 weeks after planting (WAP) of maize. A basal application of 50 kg N/ha was administered. These treatments were compared with control (no fertilizer, no mucuna), sole application of 50 and 100 kg N/ha. In Experiment II, complementary application of 0, 50 and 100 kg N/ha with incorporation of mucuna biomass, which was sown in the previous year, were administered to maize. The results showed that intercropping of maize with mucuna at planting (0 WAP) recorded averagely 46, 60 and 87 per cent of the yields for maize that received 100, 50 and 0 kg N/ha alone, respectively. The maize yield increased as sowing date of mucuna was delayed. Undersowing of mucuna at 6 and 8 WAP with application of 50 kg N/ha resulted in 30-62 per cent higher yield than at 0-4 WAP, and was comparable (91%) with application of 100 kg N/ha. It also had residual effect of average yield increase of 52 per cent over the latter. Soil analysis showed positive residual effect on soil fertility. Planting of mucuna under maize raised the organic C, exchangeable Ca and Mg by 81, 14 and 28 per cent, respectively, when compared with the chemically fertilized soil. The soil N and P levels also showed 48 and 25 per cent increase, respectively. Complementary application of 50 kg N/ha with incorporation of mucuna biomass increased plant height, biomass weight, and grain yield of maize by 18, 23 and 31 per cent, respectively, compared with incorporation of mucuna alone. The former was equally effective as the complementary use of 100 kg N/ha. The results suggest that undersowing of mucuna in relay with maize could be a good practice for sustaining soil fertility in a cerealbased cropping system. Ghana Journal of Agricultural Science Vol. 37 2004: 15-2