Agronomic productivity of conventional and low-external-input cropping systems and their effect on giant foxtail (Setaria faberi) population dynamics

Abstract

Low-external-input (LEI) cropping systems that include forage legumes and small grains in addition to corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] can achieve similar or higher crop productivity and economic return than conventional corn-soybean rotations. We hypothesized that this rotation effect occurs regardless of the crop genotype planted and the herbicide and cultivation regime selected for weed management. To test this hypothesis, we compared over a 3-year period three cropping systems: a conventional 2-year corn-soybean rotation, a 3-year corn-soybean-oat (Avena sativa L.)/red clover (Trifolium pretense L.) rotation, and a 4-year corn-soybeanoat/alfalfa-alfalfa (Medicago sativa L.) rotation. Within each cropping system, two management strategies were contrasted: (i) genetically engineered (GE) corn with resistance to European corn borer (Ostrinia nubilalis Hubner) and corn rootworms (Diabrotica spp.) plus the broadcast application of preemergence herbicides (PRE), followed in the rotation by a genetically engineered soybean variety with resistance to the herbicide glyphosate plus the postemergence broadcast application of glyphosate