Barnyardgrass (Echinochloa crus-galli) Interference in Soybeans (Glycine max)
A 2-yr field experiment was conducted at Fayetteville and Stuttgart, AR, to predict soybean yield loss as a function of barnyardgrass density and total dry weight. Predicted soybean yield reductions were 0 to 78% for original densities of 1 to 500 barnyardgrass plants per m of row. Soybean yield reductions were linear from 0 to 150 barnyardgrass plants per m of row with an average yield reduction of 0.25% for each plant per m of row. Soybean yield was reduced 10, 25, and 50% from original barnyardgrass densities of 42, 110, and 250 plants m of row. Predictions of soybean yield reduction from barnyardgrass dry weight and original density were similar. traspecific interference of barnyardgrass occurred for all variables tested, with individual barnyardgrass plants becoming less competitive as density increased.