Multi-Crop Annual Forage Production for Improved Manure Management in Wisconsin.

Alternative forage systems that increase the number of opportunities for summer manure applications and provide high quality feed are required to improve dairy slurry management.  Two site-year locations of research were conducted near Arlington and Elkhorn, WI to assess a sequence of multiple annual grasses compared to full season corn silage (Zea mays L.) for dry matter yield, forage quality, and soil nutrient accumulation.  Three systems were developed that provided two additional openings for summer manure spreading: (1) spring sown oat (Avena sativa L.)/pea (Pisum sativum L.), summer sown BMR sudangrass (Sorghum bicolor subsp. drummondii) (cut once), fall sown oat, (2) fall sown winter rye (Secale cerale L.) (cut once), spring sown BMR sudangrass (cut twice), fall sown oat and (3) fall sown winter rye (cut twice), fall sown oat.  Oat and rye forages were harvested near boot stage, sudangrass was harvested between 0.9 to 1.2 m in height while corn silage was harvested at 50% kernel milkline. MILK2006 model estimated milk per ton and per ha with forage composition data.  Corn silage produced 30 to 44% more biomass than the cumulative forage production of the alternative forage systems. Estimated milk production from corn silage was 44 to 46% greater than other systems. No significant difference in forage nitrogen or phosphorus uptake occurred among systems. Although mixed grass systems received 119 to 310 kg ha^-1 more nitrogen from manure, the corn silage system soil nitrate accumulation was significantly higher in the lowest third of the 0.9 m profile. When compared to corn silage the addition of alternative forage systems increased spreading options but decreased both biomass and milk production.