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Agronomy Journal Abstract - Organic Agriculture & Agroecology

In-Season and Carry-Over Effects of Cover Crops on Productivity and Weed Suppression


This article in AJ

  1. Vol. 108 No. 4, p. 1624-1635
    Received: Sept 01, 2015
    Accepted: Mar 20, 2016
    Published: May 6, 2016

    * Corresponding author(s): richard.smith@unh.edu
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  1. Elisabeth A. Hodgdona,
  2. Nicholas D. Warrenb,
  3. Richard G. Smith *b and
  4. Rebecca G. Sidemanc
  1. a Department of Biological Sciences, University of New Hampshire, Durham, NH 03824 and Department of Plant and Soil Science, University of Vermont, Burlington, VT 05405
    b Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH 03824
    c Department of Biological Sciences, University of New Hampshire, Durham, NH 03824
Core Ideas:
  • Cover crops differ in their ability to provide multiple ecosystem services.
  • This study quantified weed suppression services in 12 cover crop treatments.
  • Weed suppression in fall, spring, and a subsequent phytometer differed among the treatments.
  • Phytometer biomass was higher following forage radish and several legume cover crops compared to annual ryegrass.
  • Cover crop multi-functionality and tradeoffs were assessed with spider plots.


Data necessary to evaluate cover crop multifunctionality are lacking, particularly for cool, short-season cropping niches typical of northern New England. We quantified cover crop biomass, weed suppression, and carry-over effects on subsequent crop and weed growth in 12 winter cover crop treatments {monocrops and mixtures of annual ryegrass [Lolium multiflorum Lam.], winter rye [Secale cereale L.], alfalfa [Medicago sativa L.], crimson clover [Trifolium incarnatum L.], white clover [T. repens L.], hairy vetch [Vicia villosa Roth], soybean [Glycine max (L.) Merr.], and forage radish [Raphanus sativus L.], and a weedy fallow [control] treatment}. The forage radish treatments (11 and 28 kg ha–1 seeding rates) were among the highest producers of fall cover crop biomass in all 4 site-years. The forage radish treatments were also among the most weed-suppressive in the fall, reducing weed biomass relative to the weedy fallow treatment by 89 to 97% in each of the 4 site-years. In the spring, annual ryegrass was among the highest (ranging from 349–571 g m–2 across site-years) and alfalfa was among the lowest (39–287 g m–2) biomass-producing treatments in 3 out of 4 site-years. Weed biomass in the spring was 73 to 99% lower in annual ryegrass, hairy vetch, and hairy vetch–winter rye mixture treatments than in the weedy fallow treatment. Biomass of the sorghum [Sorghum bicolor (L.) Moench]–sudangrass [S. sudanense (Piper) Stapf] phytometer was higher following white clover, hairy vetch, the hairy vetch–rye mixture, and both forage radish treatments compared to following annual ryegrass.

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