No-till production farmers can cut herbicide use, control weeds, protect profits

Date:
August 23, 2021
Source:
Penn State
Summary:
Farmers using no-till production -- in which soil never or rarely is
plowed or disturbed -- can reduce herbicide use and still maintain
crop yields by implementing integrated weed-management methods,
according to a new study.



FULL STORY ========================================================================== Farmers using no-till production -- in which soil never or rarely is
plowed or disturbed -- can reduce herbicide use and still maintain crop
yields by implementing integrated weed-management methods, according to
a new study conducted by Penn State researchers.


========================================================================== While no-till agriculture can conserve soil and energy, it relies
primarily on herbicides for weed control and to terminate cover crops
and perennial crops, noted the study's lead author, Heather Karsten,
associate professor of crop production/ecology. When farmers are no
longer using tillage to disrupt weed growth, they typically use more
herbicides to control weeds.

"Farmers are particularly reliant on a few common herbicides for no-till production of corn and soybeans, such as glyphosate, which has resulted in
the evolution of herbicide-resistant weeds that are now very problematic,"
she said. "With more than 65% of agronomic crops under no-till production
in Pennsylvania, those weeds are spreading, reducing crop yields and
becoming very difficult to control." Karsten's research group in the
College of Agricultural Sciences has been studying sustainable dairy
farming for more than a decade in experiments at Penn State's Russell
E. Larson Agricultural Research Center at Rock Springs.

This integrated-weed-management study is the latest spinoff from that
larger research project.

To test whether herbicide applications could be reduced in no-till
production, lessening the environmental impact and selection pressure
for herbicide resistance, researchers conducted a nine-year experiment
using herbicide- reduction practices in a dairy crop rotation.

The rotation included soybean, corn with fall-planted cover crops,
and three years of alfalfa, followed by winter canola. The following
practices were used to reduce herbicide inputs: 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 once in six years to
terminate the perennial forage rather than killing it with an herbicide.

These practices were compared with standard herbicide-based weed
management in continuous no-till, which consists of repeated herbicide applications. To measure the results, researchers sampled weed biomass
in soybean, corn and the first two alfalfa forage years.

n findings recently published in Agronomy Journal, the researchers
reported that there was more weed biomass in the reduced herbicide
treatment, leading to more weeds over the years in the reduced-herbicide
corn and soybean treatments -- but that the added weed pressure did not substantially affect crop yields or differences in net return. In the
following alfalfa forage seeding year, weed biomass was rarely greater
in the reduced-herbicide treatment, and was never greater by the second
year of alfalfa forage.

Crop yield and differences in net return were similar in most crops and
years, Karsten pointed out, explaining that the research results suggest
that using an integrated-weed-management approach with reduced herbicide
inputs can be effective.

"In this long-term study, we demonstrated that herbicide reduction is
viable provided there is a diverse rotation with a broad array of control methods," she said. "Increasing crop life-cycle diversity can reduce weed outbreaks and selection pressure for herbicide-resistance weeds. Using an integrated approach, it is possible to make agriculture more sustainable
and environmentally friendly without decreasing productivity."
Also involved in the research were Haleigh Summers, master's degree
student in plant science; Glenna Malcolm, associate teaching professor
of biology; and William Curran, professor emeritus of weed science.

The U.S. Department of Agriculture's National Institute of Food and
Agriculture funded this research.

========================================================================== Story Source: Materials provided by Penn_State. Original written by Jeff Mulhollem. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Haleigh Summers, Heather D. Karsten, William Curran, Glenna
M. Malcolm.

Integrated weed management with reduced herbicides in a
no‐till dairy rotation. Agronomy Journal, 2021; 113 (4):
3418 DOI: 10.1002/ agj2.20757 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210823125646.htm

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