Soil Fertility Weed Biomass And Cowpea Vigna Unguiculata L. Walp Performance Under Different Cowpea Based Intercropping Systems

ABSTRACT Although in Southwestern Nigeria many aspects of Agronomy of cowpea have been accorded research attention with a view to raising its present yield on farmers farms However there is still dearth of published scientific data and information on soil nutrient status and weed biomass as affected by cowpea based intercropping systems. To this end a two year field experiment was conducted in 2010 and 2011 cropping seasons at the Teaching and Research Farm of the Ekiti State University Ado Ekiti Ekiti State Nigeria to evaluate the effects of different cowpea based crop mixtures on soil nutrient status weed biomass yield and yield components of cowpea Vigna unguiculata. The experiment was laid out in a randomized complete block design with three replicates. The different cowpea based crop mixtures included sole cropped cowpea SCC which served as the control cowpea maize CM cowpea cocoyam CC and cowpea okra melon COM. The results obtained indicated existence of significant P 0.05 differences among the different cowpea based crop mixtures as regards their effects on weed biomass yield and yield components of cowpea. Relative to the initial nutrient status of the soil prior to 2010 cropping season the percentage decreases in soil organic carbon SOC adduced to cowpea based mixtures after 2010 cropping season were 9 18 27 and 23 for the respective SCC CM CC and COM. Conversely at the end of 2011 cropping season increases of 5 14 21 and 27 in SOC were recorded for SCC CM CC and COM respectively. At the end of 2010 cropping season cowpea based mixtures resulted in decreases of 8 31 23 and 18 in total N for the respective SCC CM CC and COM. On the contrary at the end of 2011 cropping season cowpea based mixtures resulted in increases of 10 18 3 and 26 in total N for SCC CM CC and COM respectively. Available P decreased at the end of 2010 cropping season by 7 21 16 and 26 for the respective SCC CM CC and COM. In contrast available P increased at the end of 2011 cropping season by 9 21 16 and 28 for SCC CM CC and COM respectively. The mean values of cowpea seed yield data over the two years of experimentation indicated that cowpea - based intercropping significantly decreased cowpea seed yield from 4.3 t ha-1 for SCC to 3.77 3.32 and 3.98 t ha-1 for CM CC and COM respectively.