Reducing Tillage on Organic Dryland Farms in the Northern Great Plains with Grazers.

Reliance on tillage for organic dryland farms in the Northern Great Plains is a key sustainability challenge. We are integrating grazers as an alternative to tillage for cover crop termination and weed control to reduce tillage-related soil erosion.  Study sites at a research station in southwestern Montana (Bozeman) and an on-farm trial in north-central Montana (Big Sandy) were used to compare winter pea (Pisum sativum) and sweet clover (Melilotus alba) cover crop termination by sheep or tillage for their subsequent impacts on crop growth and weed composition.  In Bozeman, winter pea shoot biomass averaged 3 Mg/ha for the grazed plots and 5.2 Mg/ha for the tilled plots adding 127 kg/ha versus 188 kg/ha biomass N respectively, due to later termination date in the tilled plots.  The Big Sandy trial yielded lower shoot biomass overall, averaging 540 and 600 kg/ha and 14 and 16 kg/ha N for the grazed and tilled treatments, respectively.  We will also present grain yields and weed community composition data from the following 2014 crop.