Agronomic and economic performance characteristics of conventional and low-external-input cropping systems in the central corn belt.

Autor: Liebman, M.; Gibson, L.R.; Sundberg, D.N.; Heggenstaller, A.H.; Westerman, P.R.; Chase, C.A.; Hartzler, R.G.; Menalled, F.D.; Davis, A.S.; Dixon P.M.
In:

Agronomy Journal 100, 600-610

Bandangabe: 100
Seite: 600 - 610
Jahr: 2008

Einordung:
Institut: Professur Phytomedizin

Abstract:
We conducted a 9-ha fi eld experiment near Boone, IA, to test the hypothesis that yield, weed suppression, and profi t 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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