Submitted to: Clean Water Clean Environment 21st Century Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/5/1995
Publication Date: N/A
Interpretive Summary: The use of fertilizers and pesticides for corn and soybean production in the Midwest Region is the most extensive in United States. Reduced use without loss of production can have a major impact on surface and groundwater quality. Ridge tillage is most prevalent in this Region and imparts significant agronomic advantages as frequently documented in technical and popular literature. Ridge tillage for corn and soybeans was tested against other tillage systems in all seven MSEA locations--direct linkages were made between agrichemicals application and potential movement into groundwater. This extensive, multi-location test of tillage-system impacts on water quality in the Midwest will provide a critical evaluation of ridge tillage and some of the opportunities it provides to diminish groundwater damage.
Technical Abstract: Water quality management is suggested to be sensitive to tillage systems but direct traces of agrichemical movement are necessary to determine if and how tillage and agrichemical application strategies can be used to control/reduce escape from the target site. Ridge tillage (RT) is a somewhat new system that offers agronomic and soil conservation advantages, although it is not a system adaptable to tillage rotation. Depending on practices in a no-till it may approach RT. Information from seven MSEA sites indicated that RT with corn-soybean rotation achieved weed control with banded herbicide--with a 50 to 60 % reduced loading rate. Other tillage systems also required postplant cultivation to avoid excessive loading rate of herbicide. Alachlor migration in soil was nil and did not reach an aquifer; when atrazine was detected in an aquifer, concentrations rarely exceeded MCL=3 ppb. RT not only facilitated reduced herbicide loading, but also provided a means to separate both herbicide and fertilizer from the macropores. Macropores are well-known to facilitate bypass movement of agrichemicals to aquifers. Crop rotation, reduced loading rate with more frequent smaller amounts applied--both reduced nitrate escape to aquifers.