Weed interference and control in soybean, as affected by row spacing, in the transition zone of South West Nigeria

Abstract

ABSTRACTWeed interference is a major factor attributed to the poor yields of soybean (Glycine max L.) in Nigeria. Field experiments were conducted to evaluate the effect of row spacing on weed interference and control in soybean. Fifty-centimeter row spacing (35 plants m−2) caused a significant reduction in weed density and dry matter, resulting in an increase in soybean grain yield compared with 75- (133 plants m−2) and 100-cm row spacing (146 plants m−2). Under season-long weed interference, weed density at 50-cm row spacing was 74–76% lower than that at 75-cm and 100-cm row spacing. Irrespective of row spacing, there was no yield reduction when weeds were allowed to grow until 3 weeks after sowing (WAS). However, weed growth until 6 WAS or longer resulted in a significant yield reduction. With 50-cm row spacing, soybean produced optimum yield (2180 kg ha−1) with as little as 6 weeks of weed-free period. However, optimum yield at 75-cm (1983 kg ha−1) and 100-cm (1833 kg ha−1) row spacing was produced with 9 weeks of weed-free period. Butachlor + hand hoeing reduced weed density and dry matter and provided additional yield benefit over three hand hoeings or sole application of butachlor when the crops were planted at 50-cm or 75-cm row spacing. However, at 100-cm row spacing, three hand hoeings provided the best weed control and highest grain yield. These results showed that narrow (50-cm) row spacing + butachlor + hand hoeing provided efficient weed control and the highest yield of soybean.