Wednesday, November 15, 2006

A Uniformity Study at the Conclusion of a Long-Term Systems Trial Reveals Benefits from Organic and Living Mulch Systems.

John Teasdale and Charles B. Coffman. USDA-ARS, USDA-ARS Bldg. 001 Rm. 245, 10300 Baltimore Ave., Beltsville, MD 20705

A nine-year comparison of minimum-tillage cropping systems for grain production was conducted at the USDA-ARS Beltsville Agricultural Research Station, Beltsville, Maryland, from 1994 to 2002.  Four systems were compared: 1) a standard Mid-Atlantic no-tillage system (NT) with recommended herbicide and nitrogen inputs, 2) a cover crop-based no-tillage system (CC) including hairy vetch before corn and rye before soybean with reduced herbicide and nitrogen inputs, 3) a no-tillage crownvetch living mulch system (CV) with recommended herbicide and nitrogen inputs, and 4) a minimum-tillage organic system (OR) with cover crops and manure for nutrients and post-planting cultivation for weed control.   After nine years, competition from weeds in OR or the uncontrolled living mulch in CV was unacceptable, particularly in dry years.  On average, corn yields were 26 and 25% lower in OR and CV, respectively, than in the standard NT whereas corn yields in CC and NT were similar.  A uniformity trial was conducted from 2003 to 2005 with NT corn grown on all plots.  Yield of corn grown on plots with a nine-year history of OR or CV were 18 and 19% higher, respectively, than those with a history of NT whereas there was no difference between corn yield of plots with a history of NT and CC.  In subplots with no nitrogen applied in 2003-2005, yield reduction relative to adjacent nitrogen-treated subplots was higher in plots with a history of NT (60%) than those with a history of OR (43%) or CV (45%).  These results suggest that positive long-term changes in fertility as a result of OR and CV systems were masked by excessive competition from weeds or uncontrolled living mulch during this nine-year project.

Handout (.pdf format, 69.0 kb)