Effect of Maize –Legume Intercrop and Fertilizer on Weed Suppression and Maize Performance in South Eastern, Nigeria

Maize is one of the most commonly cultivated arable crops in the rain forest zone of South Eastern Nigeria. Globally soil fertility and weed pressure are the most important constraints limiting increase productivity of Maize especially in Sub Saharan Africa (SSA). Unavailability and cost of inorganic fertilizer as well as cost of labour for weeding have engendered low productivity of maize. Hence this trial was conducted to evaluate the efficacy of maize-legume systems on weed suppression and maize performance. The trial was carried out at the Teaching and Research Farm of Faculty of Agriculture, University of Port Harcourt, Nigeria located within latitude 04°54’N and longitude 6°55’ E). The trial was conducted between April 4th and July 5th, 2017. The experiment was a 3 x 3 factorial arrangement fitted into a randomized complete block design (RCBD) consisting of 3 types of legume systems (Mucuna pruriens, Lablab purpurens and No legume) and three levels of NPK 15:15:15 fertilizer (0, 15, and 30 kg NPK/ha). The 9 treatment combinations were replicated thrice to give 27 plots. Data collected were on maize yield and yield components, weed and legume parameters at 4, 8 and 16 weeks after sowing (WAS). Result showed that legume significantly reduced weed biomass when compared to the natural fallow. The effect of weed biomass reduction was Mucuna 34.8% >Lablab 29.2%. The legume system significantly suppressed weed compared to natural fallow and the weed suppression ability average 56% and 30% respectively for Mucuna and Lablab whether or not they received NPK. Result of this trial also revealed that within 8 weeks after sowing legumes (8 WASL) 26% N and 22% N can be harvested by integrating this legume cover in cropping system and that NPK application has little or no effect in the performance of these legumes. Mucuna was not sensitive to fertilizer application while Lablab responded to fertilizer application. Maize was sensitive to Mucuna due to early integration; hence, it is recommended that these legumes be integrated at six weeks after sowing maize.