According to a recent study done by Penn State researchers, farmers adopting no-till farming - in which soil is never or seldom plowed or disturbed - can minimize pesticide use while maintaining crop yields by applying integrated weed management strategies.
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Haleigh Summers, a master's student in plant science, Glenna Malcolm, an assistant teaching professor of biology, and William Curran, a professor emeritus of weed science, were also involved in the study. This study was supported by the National Institute of Food and Agriculture of the United States Department of Agriculture.
No-Till Production
While no-till agriculture saves soil and energy, it largely relies on pesticides for weed control and the termination of cover crops and perennial crops, according to Heather Karsten, associate professor of agricultural production/ecology and primary author of the study. Farmers usually use more pesticides to manage weeds when they no longer utilize tillage to interrupt weed development.
"For no-till corn and soybean cultivation, farmers are particularly reliant on a few popular herbicides, such as glyphosate, which has resulted in the creation of herbicide-resistant weeds that are now quite troublesome," she added. "Weeds are spreading, decreasing crop yields, and proving increasingly difficult to control in Pennsylvania, where no-till cultivation accounts for more than 65 percent of agronomic crops."
In trials at Penn State's Russell E. Larson Agricultural Research Center near Rock Springs, Karsten's research group in the College of Agricultural Sciences has been studying sustainable farming for more than a decade. This study on integrated weed control is the most recent offshoot of that broader research effort.
Researchers performed a nine-year experiment utilizing herbicide-reduction methods in a dairy crop rotation to see if herbicide usage might be decreased in no-till agriculture, reducing environmental impact and selection pressure for herbicide resistance.
Soybean, corn with fall-planted cover crops, three years of alfalfa, and winter canola were all part of the cycle. In addition, herbicide inputs were reduced by applying herbicides only in bands over corn and soybean rows and using high-residue, inter-row cultivation; seeding a small-grain companion crop such as oats with perennials alfalfa and orchardgrass, and plowing perennial forage once every six years rather than killing it with a herbicide.
These techniques were compared to traditional herbicide-based weed control in continuous no-till, which comprises recurrent herbicide treatments. Researchers took samples of weed biomass in soybean, maize, and the first two years of alfalfa forage to determine the outcomes.
Weed Management
The study published in the Agronomy Journal stated that the reduced herbicide treatment had more weed biomass, resulting in more weeds over time in the reduced-herbicide corn and soybean treatments - but that the increased weed pressure had no significant effect on crop yields or differences in net return. In addition, weed biomass was seldom larger in the reduced-herbicide treatment in the following alfalfa forage planting year, and it was never greater by the second year of alfalfa forage.
Comparing Crop Yield
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According to Karsten, crop production and variations in net return were comparable in most crops and years, suggesting that employing an integrated weed-management method with lower pesticide inputs can be effective.
"We proved in this long-term study that pesticide reduction is feasible if there is a diversified rotation with a wide range of management techniques," she added. "Weed outbreaks and selection pressure for herbicide-resistant weeds can be reduced by increasing crop life-cycle variety. It is feasible to make agriculture more sustainable and ecologically friendly without lowering production by using an integrated strategy."
