Influence of tillage and cropping systems on field emergence, growth of weeds and yield of maize (Zea mays L.) and cowpea (Vigna unguiculata L.)

The effects of land tillage and cropping system on the pattern of weed seedling emergence, weed biomass production and yield of maize and cowpea were examined at Ilorin, in the southern Guinea savanna of Nigeria. Weed emergence occurred throughout the 2-12 weeks after planting (WAP) sampling period but peaked between 4 and 8 WAP. Tillage methods had limited effect on weed emergence, whereas cropping systems significantly affected weed emergence. A significantly (p<0.05) lower number of weeds emerged in tractor ploughed, harrowed and ridged (PHR) plots compared with other tillage methods while higher weed densities and weed biomass were recorded in the sole maize and fallow plots than in the sole cowpea and maize/cowpea intercropped plots. While aggregate crop yields were significantly higher in the intercropped than in the sole plots, component crop yields were higher under the sole cropping than in the intercrop.