Research Shows Advantages of Reduced-Herbicide Crop Management

11/9/2013 7:00 AM

I have written several times about the Northeast Sustainable Agricultural Research and Educational project that numerous faculty and staff from Penn State are involved with.

The objective has been to evaluate the effects of diverse cropping strategies on a 65-cow dairy operation. Weed control is one of the primary focuses of the research.

Elina Snyder recently completed her master’s program with William Curran and Heather Karsten evaluating weed control in no-till corn and soybeans.

She was hired as the field and forage crops educator for Blair, Huntingdon, and Fulton counties. As an Extension educator, she will be applying concepts from this project at the farm level.

No-till grain production in Pennsylvania relies primarily on herbicides for weed control. However, with the increased abundance of herbicide-resistant weeds in the state and research demonstrating negative effects of herbicides, there is interest in testing different ways to manage problematic weeds.

One of Snyder’s studies conducted in 2010-12 at Penn State’s Russell E. Larson Research and Education Center evaluated methods to control weeds and maintain yields in no-till corn and soybeans.

The study compared weed control, crop yields, potential soil loss and net returns under two weed control programs.

A reduced-herbicide treatment controlled weeds by applying pre-emergence herbicide in a 10-inch band over the crop row at planting, followed by two passes with a high-residue cultivator, equipped with coulters that slice residue ahead of the sweeps to help leave it in place.

The standard-herbicide treatment used broadcast pre- and post-emergence herbicide to control weeds. A cereal rye cover crop preceded both crops and was terminated with a burn-down herbicide.

Before reduced-herbicide soybean, the rye was also roll-crimped. All corn and reduced-herbicide soybeans were planted in 30-inch rows and standard-herbicide soybeans were no-till drilled on 7.5-inch rows.

Weed density and biomass were often greater under reduced-herbicide management in both crops, but weed biomass never exceeded 170 pounds per acre in corn and 187 pounds per acre in soybeans.

Corn yields averaged 177 bushels per acre with reduced herbicides and 175 bushels per acre with standard herbicides (15.5% moisture) across the three years of the project.

Using a partial budget, net returns to management were $37 an acre higher in reduced-herbicide corn from slightly higher yields and lower herbicide costs.

Soybean establishment was challenging with both the no-till drill and planter in 2011 and particularly 2012, as the warm spring resulted in very heavy cover-crop residue.

Only the standard-herbicide treatment was replanted in these years, though population counts in 2012 revealed that the reduced-herbicide treatment also had poor stands. Slugs may have contributed to this.

The re-planted soybeans with standard herbicides had higher yields in these two years, likely due to the population differences.

Soybean yields averaged 63 bushels per acre for standard herbicides (drilled) and 54 bushels per acre for for reduced herbicides (planted), both at 13 percent moisture for 2010-12.

Assuming re-planting was unnecessary, standard-herbicide management would have higher net returns than reduced-herbicide management, but using different herbicides and equipment could also affect returns.

The NRCS revised universal soil loss equation, or RUSLE 2, software was used to estimate potential soil loss and disturbance from these weed management practices.

Even when two passes with a high-residue cultivator were made each year, reduced-herbicide management still met national standards for no-till.

Soil losses increased with cultivation, particularly on steeper slopes. Although cover-crop residue prevents soil loss, cultivating twice each year on a 10 percent slope is not recommended, even with heavy residue.

Overall, reduced-herbicide management proved effective in controlling weeds in both crops. In corn, comparable yields and higher returns to management presents reduced-herbicide management as a viable option for no-till producers in central Pennsylvania.

Challenges in soybean establishment under both management systems indicate that planting technology should be improved for establishing no-till soybeans in high-residue environments.

More information on these results can be directed to Snyder at 814-940-5989 or ems389<\@>psu.edu.

Virginia “Ginny” Ishler is a nutrient management specialist and manager of Penn State University’s dairy complex.


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12/21/2014 | Last Updated: 10:30 AM