Optimizing Cover Crop Benefits with Diverse Mixtures and an Alternative Termination Method

Abstract

Previous studies have demonstrated benefi ts of individual cover crop species, but the value of diverse cover crop mixtures has received less attention. Th e objectives of this research were to determine the eff ects of spring-sown cover crop mixture diversity and mechanical cover crop termination method on cover crop and/or cash crop productivity, soil moisture and N, and profi tability in an organic cropping system. An experiment was conducted between 2009 and 2011 near Mead, NE, where mixtures of two (2CC), four (4CC), six (6CC), and eight (8CC) cover crop species, or a summer annual weed mixture were included in a sunfl owersoybean-corn rotation. Cover crops were terminated in late May using a fi eld disk or sweep plow undercutter. Undercutting cover crops increased soil NO 3 -N (0-20 cm) by 1.0 and 1.8 mg NO 3 -N kg -1 relative to disk incorporation in 2010 and 2011, respectively. Cover crop mixtures oft en reduced soil moisture (0-8 cm) before main crop planting, though cover crop termination with the undercutter increased soil moisture content by as much as 0.024 cm 3 cm -3 compared to termination with the disk during early main crop growth. Crop yields were not infl uenced by cover crop mixture, but termination with the undercutter increased corn and soybean yield by as much as 1.40 and 0.88 Mg ha -1 , respectively. Despite diff erences in productivity between spring cover crop mixtures and weed communities, crop yield was not diff erent among these treatments; thus, profi tability of the weed mixture-undercutter treatment combination was greatest due to reduced input costs. ).Abbreviations: CC, cover crop mixture; DAT, days aft er termination; DOY, day of year; NC, weed-free and cover crop-free control; WD, weedy mixture and cover crop-free.

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