Organic No-Tillage Winter Rye-Soybean Systems: Agronomic, Economic, and Environmental Assessment.

Research was conducted near Arlington, Wisconsin to determine agronomic, economic, and environmental risks associated with the use of winter rye as a mulch in no-till, organically-managed soybean production systems relative to a tillage-intensive approach.  Our objectives were to determine the effects of rye management (plowing, crimping, and mowing), and soybean planting date (mid-May or early June) on soil moisture availability, soybean stand establishment, weed suppression, and soybean yield.  Soil loss and economic gross margins were also estimated.  Following a dry May in 2008, surface soil moisture levels (0-6 cm) were at the permanent wilting point in all treatments, and the measurements indicated that rye reduced available moisture to a depth of 57 cm. Heavy precipitation in June increased soil moisture content to near field capacity until late July in all treatments.  Rye management did not affect soybean stand establishment among treatments planted in mid-May, but soybean stand establishment for treatments planted in June was half of those planted in mid-May.  Although late-season weed shoot mass was nearly nine times greater in the tillage-intensive treatment than in no-till treatments, soybean yield was also greater in the tillage-intensive treatment.  Within no-till treatments, soybean yields did not differ between crimped and mowed rye treatments, but largely due to greater stand establishment, soybean yields were greater for the mid-May than June planting date.  Due to fewer costs in the no-till treatments, gross economic margins did not differ between mowed rye and tillage-intensive treatments planted in mid-May.  Estimated soil loss in the no-till treatments was less than 20% of that in the tillage-intensive treatment.  The results suggest that these no-till, organically-managed soybean production systems were viable economic alternatives to a tillage-intensive approach, with the benefits of greater weed suppression and soil conservation.