Agronomics and economics of different weed management systems in corn and soybean

The USDA has a goal of implementing integrated pest management (IPM) practi ces on 75% of crop area by 2000. Growers require more economic information before adopting IPM practices. A field study was initiated in New York to e valuate meed control, fields, and net returns of chemical (broadcast herbic ides), chemical-mechanical (banded herbicides and cultivations), and mechan ical (rotary hoc and cultivations) weed management under moldboard pion and chisel tillage in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. Chemical and chemical-mechanical need management had similar corn net retu rns under moldboard plow ($370 and $355 ha(-1), respectively) and chisel ti llage ($282 and $287 ha(-1)). Mechanical weed management had less net retur ns in moldboard plow ($302 ha(-1)) and chisel tillage ($121 ha(-1)) because of 15% lesser corn densities and greater weed densities, especially in chi sel tillage. In soybean, mechanical weed management in moldboard plow tilla ge had similar weed density (1.5 weeds m(-2)) lower yield (2.71 Mg ha(-1)), but similar net return ($107.50 ha(-1)) compared with chemical (1.3 weeds m(-2), 2.92 Mg ha(-1), and $85.60 ha(-1), respectively) and chemical-mechan ical weed management (1.0 weeds m(-2), 2.78 Mg ha(-1) and $99.35 ha(-1), re spectively). In chisel tillage, mechanical weed management had greater need density (7.4 weeds m(-2)), lower yield (2.2 Mg ha(-1)), and lower net retu rn (-$7.80 ha(-1)) compared with chemical (1.9 weeds m(-2), 2.8 Mg ha(-1), and $56.80 ha(-1), respectively) and chemical-mechanical weed management (1 .9 weeds m(-2), 2.4 Mg ha(-1), and $27.30 ha(-1)). Corn and soybean growers apparently con adopt chemical-mechanical weed management and maintain net returns. Soybean growers who use moldboard plow tillage can also adopt mech anical weed management and maintain net returns.