Using the Roller/Crimper to Terminate Annual Green Manures in Organic Production Systems.

Organic grain producers rely on green manures (GM) to return essential nutrients to their cropping systems; however, problems with the use of GM are depletion of soil moisture and potential negative effects associated with excessive tillage. Legume green manures supplying high amounts of N and P, and management techniques optimizing nutrient cycling and soil moisture retention are needed for successful GM use. This multiple-year field study conducted in the Canadian prairies explores the effect of termination timing and method of legume GM on subsequent cereal production and soil health indicators. The roller/crimper is compared to tillage for its effectiveness in terminating GM in an organic prairie agriculture system.  The implement kills GM by crimping the stems, leaving a layer of mulch on the soil surface expected to reduce surface evaporation. Soil and plant samples were taken from those plots being terminated in 2009 within one week of termination, with soil sampling repeated in the fall of 2009 and spring of 2010. Green manure total N and P uptake and soil concentrations of NO3-, NH4+ and PO4- and moisture content will be presented for 2009. Data from the grain harvest post-treatments will be presented, included yield, grain protein content, and total N and P uptake. Effects of GM management on nutrient availability, soil moisture and biological indicators of soil health will be discussed.