Long-term study evaluates impacts of six Wisonsin cropping systems (Research Brief #11)
Posted March 1993
Wisconsin cash grain and dairy livestock cropping systems have gone on trial. The goal is to identify and evaluate trade-offs of various production strategies.
An interdisciplinary team of UW-Madison and Michael Fields Agricultural Institute (MFAI) researchers, farmers, and two county extension agents recently completed the third year of the Wisconsin Integrated Cropping Systems Trial (WICST). The project is comparing the productivity, profitability, and environmental impacts of three dairy and three cash-grain crop rotations.
In recent years, public debate had grown over the sustainability and environmental impact of various farming practices. Little agreement exists on how to measure the environmental effects of agriculture. In addition, farmers currently may find it difficult to adopt practices that help the environment in the long term in a system dominated by short-term economic concerns.
“There has been a lack of good comparisons between the best of the conventional agriculture practices and the best of the alternative agricultural systems,” says Josh Posner, UW-Madison agronomist and a project coordinator.
Research design and details
WICST is being conducted over 16 years at the Walworth County Lakeland Agricultural Complex and the UW-Madison Arlington Agricultural Research Station in Columbia County. The Lakeland Ag Complex has a somewhat poorly drained soil and the water table is within 15 feet of the surface. At the Columbia County site, the soil is much deeper and better drained with the water table about 100 feet below the surface.
WICST includes core rotation trials, long-term field monitoring, satellite experiments, and on-farm demonstration trials. Education and information dissemination play an important role in the project. Both sites have been developed into area outdoor learning centers, with annual field days and other visits by farmers, environmentalists, students, policy-makers, and the public scheduled regularly at both sites. More than 3,000 visitors toured the two WICST locations in 1991 and 1992.
Core rotations in the cash grain systems include high-input continuous corn, a corn-soybean rotation, and a low-input soybean-wheat/clover-corn rotation. On the dairy side of the core experiments, the WICST team is evaluating an intensive alfalfa-based program, a more typical oat/hay-corn rotation, and a low-input rotational grazing system on a grass/legume pasture.
Two of the cash grain rotations and the high-input forage rotation rely on commercial fertilizer. The low-input cash grain system uses a red clover green manure crop to partially supply nitrogen needs.
A short-term objective (4 to 8 years) of the WICST project is to quantify the “transition costs” of adopting lower-input production strategies. In the longer term (12 to 16 years), the project will focus on the environmental and economic impacts of each system.
A systems focus for production research
The WICST study differs from most conventional research because it compares entire production strategies, not just various production components such as tillage and manure management techniques, fertilizer levels, or herbicide rates. The trials also are unique because of their long-term nature and 3/4 acre plot size, which allows the use of typically sized farm equipment.
Monitoring stations have been established to evaluate long-term changes in weed, disease and insect populations, soil fertility, and input costs. Specifically, WICST researchers monitor such components as soil nutrient levels, nitrate leaching, changes in soil structure, and flora, weed seeds, and earthworm counts in the six cropping systems.
Groundwater monitoring weeks installed at the Lakeland Ag Complex monitor long-term effects of pesticides and fertilizers in the cropping systems.
The project introduces an agro-ecological approach toward production agriculture to broaden the range of alternative practices available to farmers, Posner notes. These practices include use of cover crops, rotational grazing, mechanical weed control and conservation tillage.
Some preliminary results from the trial include the following:
- Plots where first-year corn followed soybeans yielded 15 to 20 percent higher than continuous corn. Corn grown in the low-input system yielded about one-third less than corn in the other two systems.
- The economic analysis, conducted using gross margins (total revenues minus direct costs), indicate advantages to the corn-soybean and soybean-wheat/clover-corn rotations. While too early in the study to make definitive statements about these systems, the results indicate that the other crops in the rotation and lower-input costs contribute significantly to the profitability of these two rotations.
- In corn and soybean plots, it appears that at least two rotary hoeings and two cultivations are needed to achieve yields equal to plots that receive the recommended herbicide rates.
- Cover crops have the potential to fix nitrogen. Spring-seeded red clover in small grains and summer-seeded hairy vetch planted after a grain is taken off can provide about 140 pounds of nitrogen per acre.
- At the Lakeland site, tests showed that spring-applied bromide, a tracer, was found in the water table within six months.
“Our real target is the farmer who is looking to evaluate his system and wants to develop an integrated soil and crop management plan for his farm,” says Ray Saxby, Columbia County agricultural extension agent.
Adds John Hall, an agronomist with MFAI: “We hope this scientific comparison between crop production strategies will help growers become better managers by giving them the information they need to build production plans that fit their needs and the limitations of their resource base.”
Walworth County Agricultural Extension Agent Lee Cunningham has developed a sustainable agriculture curriculum for fourth grade students in his county. Schools that sign up for the curriculum visit the Lakeland Agricultural Complex, where students participate in taking earthworm counts, identifying plant species, and learning about groundwater.
“Although 75 percent of Walworth County land is in agriculture, only 1,000 of its 75,000 residents are directly engaged in farming,” says Cunningham. “Our goal is not only to educate public officials who are making policy about agriculture, but also to educate the general public.”
WICST has received support from CIAS, UW-Madison College of Agricultural and Life Sciences, the Kellogg Foundation, Wisconsin DATCP, Wisconsin DNR and Pioneer Hi-Bred International Seed Company.
For more information about the WICST project contact:
Department of Agronomy
University of Wisconsin-Madison
Madison, WI 53706
1450 Linden Drive
UW-Madison, Madison, WI 53706
E-mail: Don Schuster
Published as Research Brief #11