Reducing Herbicide Use in a No-till Dairy Cropping System.

The Sustainable Dairy Cropping Systems Project is an interdisciplinary experiment being conducted in central Pennsylvania, USA. This no-till cropping system consists of two diverse six-year crop rotations designed to produce all of the feed, forage, and fuel needed to sustain a 65-cow dairy herd. Winter canola (Brassica rapa L.) is included to serve as an on-farm fuel and feed source. Managing weeds in these diverse, reduced-tillage rotations, with less herbicide, is the focus of this work.  Specifically, we are using integrated weed management tactics to control weeds in no-till corn (Zea mays L.), soybean (Glycine max L.).

Weed management comparisons include a “Standard Herbicide” (SH) and “Reduced Herbicide” (RH) approach. The SH treatment employs a standard herbicide-based program, while the RH treatment uses less total herbicide by incorporating rolling cover crops, banded herbicides over crop row followed by high-residue inter-row cultivation, and planting companion crops. Weed density and biomass are quantified to evaluate treatment effectiveness. Weed density and biomass, as well as crop yields and quality are quantified.

In 2010 and 2011, weed density and biomass were often greater in RH than in SH corn and soybeans. Corn grain yield did not differ between treatments in either year; yield did not differ between soybean treatments in 2010. In 2011, the proportion of weeds in forage crops, and forage yield did not differ between alfalfa treatments. Given crop productivity and projected milk yield, the RH program appears to be a viable option in no-till corn and soybean, to reduce herbicide use. Research will be repeated in 2012; data from 2011 and 2012 (if available) will be reported.