Tuesday, November 6, 2007
212-8

Effects of a Winter Rye Double Crop after Corn Silage on Water Quality, Soil Nutrient Status, and Biomass Production.

Erik Krueger1, Tyson Ochsner2, Paul Porter1, Donald Reicosky2, and John Baker3. (1) Department of Soil, Water, and Climate, University of Minnesota, 1991 Upper Buford Circle, St. Paul, MN 55108, (2) USDA-ARS, 1991 Buford Circle, St. Paul, MN 55108, (3) 439 Borlaug1991 Upper Buford, USDA-ARS, University of Minnesota, St. Paul, MN 55108

The number of dairy farms in the Upper Midwest is decreasing while the average dairy farm size is increasing. Large dairies are likely to have a different environmental impact than smaller dairies. Issues often associated with large dairies include corn silage production to support the dairy herd and land application of manure produced at the dairy. The relatively short growing season and complete biomass removal associated with corn silage production leaves the soil prone to nutrient leaching, erosion, and loss of organic matter. Potential over application of manure produced at the dairy can lead to nutrient leaching and phosphorous buildup. We suggest that rye double cropping after corn silage removal can address these issues. We hypothesize that the rye will uptake excess soil nutrients thus reducing nutrient leaching and phosphorous buildup, while also maintaining soil organic matter. The increased surface cover provided by the rye may also reduce soil erosion. Additionally, the rye is source of forage which can have a positive economic impact on the dairy. To test these hypotheses, two field studies have been designed. The first involves direct on farm cooperation with the operator of several large dairies (total herd of about 15,000 milking cows), while the other is a plot scale project designed to mimic the practices of dairy. At the farm scale, corn silage production systems with and without a rye double crop will be compared. The effect of the rye double crop on soil nutrient status, soil carbon, nutrient loss through subsurface drainage, and total biomass production will be examined. The objectives of the plot scale study are similar, but the effect of rye harvest date on forage quantity and quality will also be examined.