Increasing crop rotation diversity while reducing herbicide applications may maintain effective weed control while reducing freshwater toxicity. To test this hypothesis, we applied the model USEtox 2.0 to data from a long-term Iowa field experiment that included three crop rotation systems: a 2-year corn-soybean sequence, a 3-year corn-soybean-oat/red clover sequence, and 4-year corn-soybean-oat/alfalfa-alfalfa sequence. Corn and soybean in each rotation were managed with conventional or low-herbicide regimes. Oat, red clover, and alfalfa were not treated with herbicides. Data from 2008-2015 showed that use of the low-herbicide regime reduced freshwater toxicity loads by 81-96%, and that use of the more diverse rotations reduced toxicity and system dependence on herbicides by 25-51%. Mean weed biomass in corn and soybean was <25 kg ha-1 in all rotation × herbicide combinations except the low-herbicide 3-year rotation, which contained ∼110 kg ha-1 of weed biomass. Corn and soybean yields and net returns were as high or higher for the 3- and 4-year rotations managed with the low-herbicide regime as for the conventional-herbicide 2-year rotation. These results indicate that certain forms of cropping system diversification and alternative weed management strategies can maintain yield, profit, and weed suppression while delivering enhanced environmental performance.
Bibliographical noteFunding Information:
We express our thanks to Craig Chase, Ann Johanns, Michael Fiscus, David Sundberg, and Matthew Woods for assistance with field work and economic analyses. This research was supported by research grants from the US Department of Agriculture National Research Initiative (Projects 2006-35320- 16548 and 2014-67013-21712), the Leopold Center for Sustainable Agriculture (Projects 2007-E09, 2010-E02, 2013- XP01, and 2014-XP01), and the Iowa Soybean Association.
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't
- Research Support, U.S. Gov't, Non-P.H.S.