Effect of Row Spacing and Weeding Regime on Weed Management in Soybean (Glycine max (L.) Merrill)

Abstract

Weed interference is a major factor attributed to the poor yields of soybean in Nigeria, critical period of cropweed competition and weed threshold are two important aspects in a weed management program in any crop. This experiment was conducted to study the influence of row spacing on the competitiveness of soybeans with weeds and the effect of different periods of weed interference on weed infestation growth and yield of soybean. There are twelve treatments consisting of weed-infested and weed-free with plant density at intra-row spacing of 25 cm and 30 cm and interrow spacing of 75 cm. The treatments were laid out in a Randomized Complete Block Design (RCBD) and replicated three times. Plots where weeds were controlled for 4, 6 weeks and until harvest at 25cm spacing indicate 70–75% significant reduction in weed density and dry matter, resulting in increase in soybean grain yield compared to plot where delay in weed removal until 6 weeks or longer depressed soybean growth and resulted in irrevocable yield reduction, with the number of pods per plant being the most affected yield component. For optimum growth and yield, it was only necessary to keep the crop weed-free between 4 and 6 weeks.