HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Liebman, M. Articles by Dixon, P. M. PubMed Articles by Liebman, M. Articles by Dixon, P. M. Agricola Articles by Liebman, M. Articles by Dixon, P. M. Related Collections Sustainable Agriculture Weed Management Crop Rotation Systems Economics Production Agriculture

CROPPING SYSTEMS

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

^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

^* Corresponding author (mliebman{at}iastate.edu).

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.

Abbreviations: LEI, low-external-input

All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.

Received for publication June 22, 2007.