Cowpea, Intercropping, Maize, Nitrogen, Residual effect, Weed management, Yield

A field experiment was conducted during 2002-03 and 2003-04 at Jabalpur to study the effect of three intercropping systems viz., maize (Zea mays L.) sole, maize + cowpea [Vigna unguiculata (L.)] for grain and maize + cowpea for fodder, two treatments of weed control viz., pendimethalin 1.0 kg/ha + 1 hand weeding at 30 DAS and weedy check, and three levels of nitrogen viz. 0, 50 and 100 kg N/ha on weed infestation and crop productivity. The total weed population at 60 DAS was significantly reduced by 36 and 32% under intercropping combinations of maize + cowpea (grain) and maize + cowpea (fodder), respectively as compared to sole crop of maize. The maize grain yield was at par (2969 kg/ha) in sole maize and maize + cowpea (grain). However, it was significantly reduced to 2225 kg/ha under maize + cowpea (fodder). The maize equivalent yield was higher under maize + cowpea (grain) treatment. The maize grain yield was significantly reduced under weedy check (2140 kg/ha). Increasing levels of N significantly increased the maize grain and maize equivalent yields. The uptake of N by weeds was significantly reduced under maize + cowpea intercropping combinations. The highest net monetary returns of Rs14547/ha and B: C ratio of 1.54 were obtained from maize + cowpea (grain) treatment