Manure can provide valuable nutrients, especially nitrogen, to high N-requiring crops such as corn. However, a large portion of manure N, about half in typical liquid dairy manure, is in the ammonium or urea form and can potentially be lost to the air as ammonia if the manure is not incorporated into the soil promptly (Jokela and Meisinger, 2008). Tillage is the most common method of incorporation, but tillage and, to a lesser extent, standard injection reduce crop residue cover, leaving the field more susceptible to erosion. Tillage may also be incompatible with management requirements to meet criteria in nutrient management plans. Corn production for silage is particularly problematic because whole-plant removal leaves minimal residue cover after harvest. Establishment of a cover crop such as winter rye after harvest can provide adequate residue cover, but timely seeding (preferably by mid-September) is critical. Farmers need a system that incorporates manure while still maintaining crop residue cover.
Soil Science Extension
University of Wisconsin Madison