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This article in AJ

  1. Vol. 100 No. 3, p. 600-610
     
    Received: June 22, 2007
    Published: May, 2008


    * Corresponding author(s): mliebman@iastate.edu
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doi:10.2134/agronj2007.0222

Agronomic and Economic Performance Characteristics of Conventional and Low-External-Input Cropping Systems in the Central Corn Belt

  1. Matt Liebman *a,
  2. Lance R. Gibsona,
  3. David N. Sundberga,
  4. Andrew H. Heggenstallera,
  5. Paula R. Westermanb,
  6. Craig A. Chasec,
  7. Robert G. Hartzlera,
  8. Fabián D. Menalledd,
  9. Adam S. Davise and
  10. Philip M. Dixonf
  1. a Dep. of Agronomy, Agronomy Hall, Iowa State Univ., Ames, IA, 50011
    b Dep. Hortofruticultura, Botánica y Jardinería, Univ. de Lleida, Av. Alcalde Rovira Roure 191, 25198 Lleida, Spain
    c Iowa State University Extension, 720 7th Avenue SW, Tripoli, IA, 50676
    d Dep. of Land Resources and Environmental Sci., Leon Johnson Hall, Montana State Univ., Bozeman, MT, 59717
    e USDA-ARS Invasive Weed Management Unit, 1102 S. Goodwin Ave., Urbana, IL, 61801
    f Dep. of Statistics, Snedecor Hall, Iowa State Univ., Ames, IA, 50011. Funding for this work was provided by the USDA National Research Initiative (Projects 2002-35320-12175 and 2006-35320-16548), the Leopold Center for Sustainable Agriculture (Project 2004-E6), and the Iowa State University Agronomy Endowment

Abstract

We conducted a 9-ha field experiment near Boone, IA, to test the hypothesis that yield, weed suppression, and profit characteristics of low-external-input (LEI) cropping systems can match or exceed those of conventional systems. Over a 4-yr period, we compared a conventionally managed 2-yr rotation system {corn (Zea mays L.)/soybean [Glycine max (L.) Merr.]} with two LEI systems: a 3-yr corn/soybean/small grain + red clover (Trifolium pratense L.) rotation, and a 4-yr corn/soybean/small grain + alfalfa (Medicago sativa L.)/alfalfa rotation. Synthetic N fertilizer use was 59 and 74% lower in the 3- and 4-yr systems, respectively, than in the 2-yr system; similarly, herbicide use was reduced 76 and 82% in the 3- and 4-yr systems. Corn and soybean yields were as high or higher in the LEI systems as in the conventional system, and weed biomass in corn and soybean was low (≤4.2 g m−2) in all systems. Experimentally supplemented giant foxtail (Setaria faberi Herrm.) seed densities in the surface 20 cm of soil declined in all systems; supplemented velvetleaf (Abutilon theophrasti Medik.) seed densities declined in the 2- and 4-yr systems and remained unchanged in the 3-yr system. Without subsidy payments, net returns were highest for the 4-yr system ($540 ha−1 yr−1), lowest for the 3-yr system ($475 ha−1 yr−1), and intermediate for the 2-yr system ($504 ha−1 yr−1). With subsidies, differences among systems in net returns were smaller, as subsidies favored the 2-yr system, but rank order of the systems was maintained.

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Copyright © 2008. American Society of AgronomyCopyright © 2008 by the American Society of Agronomy