Quackgrass and Nitrogen Effects on Succeeding Crops in the Field

Abstract

Plant heights and seed yields of oats (Avena sativa L.), corn (Zea mays L.), and soybeans (Glycine max (L.) Merr.) were lower where these crops followed a heavy infestation of quackgrass (Agropyron repens (L.) Beauv.) than when they followed oats or fallow land. Application of ammonium nitrate (280 kg/ha) only partially corrected the adverse effect on yield of a previous quackgrass infestation. The effect of quackgrass persisted through the second growing season as measured by height and yield of wheat (Triticum aestivum L.) and compared with wheat after oats, corn, soybeans, or fallow, but the effect of nitrogen applied the first year only did not persist through the second year.