Evaluation of selected legume cover crops for biomass production, dry season survival and soil fertility improvement in a moist savanna location in Nigeria

Abstract

The growth and development of eighteen legume cover crop species were evaluated at the University of Ilorin Teaching and Research Farm (8o 29'N, 4o 35'E) in the southern Guinea savanna zone during the 1993 - 1996 cropping seasons. Field establishment, ground cover, above ground biomass production, and seed yields of the legume species were monitored during each cropping season. This was followed by an in-situ bioassay to determine the residual effect of the sown legume on maize (Zea mays L.) production in the absence of added nitrogen at the end of one season of legume growth each year. The results show that field establishment was generally poor (<30%) for most of the legume species, particularly the small seeded species. This resulted in a significant correlation between seed size and percent germination (r = 0.89). Similarly, seed production was poor in most of the species with the exception of Mucuna pruriens, Cajanus cajan and Crotalaria ochroleuca. On the other hand, majority of the legume species gave satisfactory ground cover, biomass production, and N contribution to the succeeding non-legume crop. Using the rank summation index, the order of adaptation of the legume species to the study location on the basis of their ground cover, biomass production, seed yield, dry season survival and N contribution to the soil was as follows: Cajanus cajan > Aeschynomene histrix > Stylosanthes guianensis > S. scabra > Crotalaria ochroleuca > C. verrucosa >Clitorea tarnatea > S. hamata > Pseudovigna argentea > Centrosema pascuorum > Pueraria phaseoloides > Lablab purpureus > Psophocarpus palustris > Chamaecrista rotundifolia > Macroptilium atropurpureum. Management practices aimed at ameliorating the poor field establishment and seed yield are suggested.