Adam S. Davis1*, Jason D. Hill2, Craig A. Chase3, Ann M. Johanns4, Matt Liebman5
1 United States Department of Agriculture/Agricultural Research Service, Global Change and Photosynthesis Research Unit, Urbana, Illinois, United States of America, 2 Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, Minnesota, United States of America, 3Leopold Center for Sustainable Agriculture, Iowa State University, Ames, Iowa, United States of America, 4 Department of Economics, Iowa State University Extension and Outreach, Osage, Iowa, United States of America, 5Department of Agronomy, Iowa State University, Ames, Iowa, United States of America
Balancing productivity, profitability, and environmental health is a key challenge for agricultural sustainability. Most crop production systems in the United States are characterized by low species and management diversity, high use of fossil energy and agrichemicals, and large negative impacts on the environment. We hypothesized that cropping system diversification would promote ecosystem services that would supplement, and eventually displace, synthetic external inputs used to maintain crop productivity. To test this, we conducted a field study from 2003–2011 in Iowa that included three contrasting systems varying in length of crop sequence and inputs. We compared a conventionally managed 2-yr rotation (maize-soybean) that received fertilizers and herbicides at rates comparable to those used on nearby farms with two more diverse cropping systems: a 3-yr rotation (maize-soybean-small grain + red clover) and a 4-yr rotation (maize-soybean-small grain + alfalfa-alfalfa) managed with lower synthetic N fertilizer and herbicide inputs and periodic applications of cattle manure. Grain yields, mass of harvested products, and profit in the more diverse systems were similar to, or greater than, those in the conventional system, despite reductions of agrichemical inputs. Weeds were suppressed effectively in all systems, but freshwater toxicity of the more diverse systems was two orders of magnitude lower than in the conventional system. Results of our study indicate that more diverse cropping systems can use small amounts of synthetic agrichemical inputs as powerful tools with which to tune, rather than drive, agroecosystem performance, while meeting or exceeding the performance of less diverse systems.
Citation: Davis AS, Hill JD, Chase CA, Johanns AM, Liebman M (2012) Increasing Cropping System Diversity Balances Productivity, Profitability and Environmental Health. PLoS ONE 7(10): e47149. doi:10.1371/journal.pone.0047149
Editor: John P. Hart, New York State Museum, United States of America
Received: July 12, 2012; Accepted: September 10, 2012; Published: October 10, 2012
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Funding: Funding for the study was provided by the US Department of Agriculture National Research Initiative (Projects 2002-35320-12175 and 2006-35320-16548), the Leopold Center for Sustainable Agriculture (Projects 2004-E06, 2007-E09, and 2010-E02), the Iowa Soybean Association, and the Organic Center. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
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