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Agronomic and Economic Performance Characteristics of Conventional and Low‐External‐Input Cropping Systems in the Central Corn Belt
Author(s) -
Liebman Matt,
Gibson Lance R.,
Sundberg David N.,
Heggenstaller Andrew H.,
Westerman Paula R.,
Chase Craig A.,
Hartzler Robert G.,
Menalled Fabián D.,
Davis Adam S.,
Dixon Philip M.
Publication year - 2008
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2007.0222
Subject(s) - agronomy , cropping system , foxtail , weed , rotation system , red clover , biology , crop rotation , weed control , mathematics , crop , nitrogen , chemistry , organic chemistry
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.