The farm of the future needs to protect soil and water resources while producing enough food for people, feed for livestock and income for farm operators. Creating a farming system that meets all those requirements is the goal of a long-term project initiated by the Ecology Initiative of the Leopold Center for Sustainable Agriculture.

Matt Liebman, Iowa State University's Henry A. Wallace Endowed Chair for Sustainable Agriculture, leads a research program at the Iowa State Marsden Farm in Boone County that promises to improve the economic performance of cropping systems while at the same time protecting environmental quality and human health. His team is comparing different crop rotation systems over time.

Use less fossil fuel without losing yield and profit

One of the objectives of this project is to find a system that relies less on fossil fuels without forfeiting yields and profits. "The dominant cropping systems in our country depend heavily on fossil fuels for fertilizing crops, drying grain and powering machinery. Reducing dependence on fossil fuels while maintaining productivity is a big challenge," Liebman said. 

The experiment uses three crop rotation systems with four replications of each pattern. The two-year rotation is a corn and soybean system that uses inputs similar to those routinely applied by other central Iowa farmers. The three-year rotation includes a small grain (oats) that follows the soybeans. The four-year rotation uses alfalfa before the corn and a small grain following the soybeans.

The three- and four-year rotations are referred to as 'low-external-input' because the systems rely more on crop diversity for pest control and a small amount of manure for nutrients. They use substantially lower quantities of purchased external inputs, such as synthetic fertilizer, pesticides and herbicides. 

3-year and 4-year rotations are producing higher yields

The three- and four-year rotations are producing higher yields than the two-year corn and soybean-only rotation. Liebman said he and his research partners are trying to find out exactly what factors are behind these results.

Labor requirements were higher in the three- and four-year systems than the conventional two-year system, but net returns from 2003 to 2008 were equivalent in the conventional two-year (corn-soybean) and LEI four-year (corn-soybean-oats/ alfalfa-alfalfa) systems. Benefits to the soil were greater among the systems with more crop diversity.

Leopold Center Ecology Initiative leader Jeri Neal says it is important to take the long view of these alternative systems. "When using a LEI system in farm management, it is critical to manage on the basis of net profitability over the long term, rather than only focusing on short-term or year-to-year results," she said.

Building healthier soils, and reducing pollution too

Not only are the longer and more diverse rotations producing higher yields over time, they're also reducing the amount of nitrogen that leaches into the groundwater and relying less on fossil fuels, says Liebman.

"We're building healthier soils and learning that relying on ecological interactions can work to the benefit of the farmer by reducing requirements for purchased inputs, particularly for things like herbicides and nitrogen fertilizer," he adds.

To learn more about this project, check out the report in the new online video section, "On the Ground with the Leopold Center", at: www.leopold.iastate.edu/research/eco_files/ground.html. Funding for this study also was provided by the USDA National Research Initiative.

The Leopold Center Ecology Initiative supports a wide range of research, demonstration and outreach projects that can build a food and agriculture system with more productive and profitable farms, ecologically resilient landscapes and healthy rural communities. It is one of three research initiatives of the Leopold Center, established in 1987 to develop sustainable agricultural practices that are both profitable and conserve natural resources.