Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/1998
Publication Date: N/A
Interpretive Summary: The most direct approach to reducing the impact of non-point source pollution on surface and groundwaters is to exert more control when the agrichemicals are applied in the field. This approach requires evaluation of the advantages of tillage systems for combined use of mechanical cultivation and herbicides to reduce the amount of herbicide applied. Different tillage systems also afford different approaches for time and method of applying N and herbicides. These studies made in different landscapes and water management in the Corn Belt did show advantages of ridge tillage for reducing agrichemical damage to environmental quality. Corn-soybean rotation also showed advantages to reduced environmental hazard from agrichemicals. This set of studies should provide guidelines, with supporting mechanistic explanations, for users and environmental planners/regulators, and scientists worldwide.
Technical Abstract: A group of eight papers were assembled from the Management Systems Evaluation Areas (MSEA) program that was established in 1990 in the Midwest region of the United States, after former President George Bush had announced in 1989 a Presidential Water Quality Initiative. Each location (one of eight states in midwestern United States) included ridge tillage with a corn-soybean sequence as a standard; applied atrazine, alachlor, an N; and traced movement of these chemicals into and through the root and vadose zones. At least one other tillage system and crop sequence (or a monocropping) was selected by each location for comparison with the standard ridge tillage treatment. This water quality research was conducted in a region that produces nearly 80 percent of the nation's corn and soybean and is a primary user of fertilizers and pesticides. This major corn and soybean producing area in the Mississippi River Basin has also been implicated for non-point source pollution contributing to hypoxia in the Gulf of Mexico. Atrazine, alachlor, and N were included in all studies because they were being detected most often in domestic wells and ground water in the late 1980's. Yet this contamination could not be traced to any particular practice or landscape. Ridge tillage was selected as the common standard because it had comparative advantages for soil and water conservation, as well as control of surficial- and ground-water quality. Ridge tillage performed well compared to other tillage systems because only a partial rate of herbicide was needed and N could be banded in the hydrologically less active ridge shoulder. Landscape influenced the advantages of ridge tillage clearly related to two factors: soil macroporosity, and climatic combined with slow soil drying factors.