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Evaluating the Use of Alfalfa as a Surface Mulch in Corn Cropping Systems

  • Deborah Allan, Dept. Soil, Water and Climate
  • Craig Sheaffer, Dept. of Agronomy & Plant Genetics
  • Laura Fernandez, Dept. Soil, Water and Climate
  • Karina Fabrizzi, Dept. Soil, Water and Climate

University of Minnesota, St. Paul Campus

Summary

Organic systems without livestock are common throughout much of the Corn Belt, requiring organic corn and grain growers to find ways to supply nitrogen (N) to their crops without manure. While alfalfa and other forage legumes grown in rotation with organic corn can generally meet crop needs, it is difficult for farmers without livestock to justify maintaining the necessary acreage of perennial forage for this practice. When organic alfalfa is grown, the hay may be sold, often resulting in the export of more than 100 kg N/ha off the farm. Although alfalfa mulch has been investigated as an N source for vegetables and small grains, little work has been done to confirm how well it can supply N to organic corn, a high N-demanding crop. Our project evaluated the use of on-farm produced alfalfa mulch as a nutrient source for production of organic corn. We found the alfalfa mulch had a positive effect on corn grain yields at one of our sites, but not the other. Alfalfa mulching to supply N affected early season corn growth and available soil N, but these effects were not consistently related to final corn grain yield, indicating that N in mulch may be lost. Despite the mixed results in the corn grain yields of our experiment, we believe alfalfa mulch has potential as a fertilizer source in organic systems.

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