Soil conservation is being threatened by rapid development of herbicide resistant weed populations, concludes a new report from CAST, the Center for Ag Science and Technology at Ames, Iowa. The report looks at the balance between conservation tillage and herbicide resistant weeds.
Herbicides were developed during the 20th century to be used with conventional tillage for weed control. Then conservation tillage came along, resulting in less soil erosion as herbicides could be used instead of tillage to control weeds. Selection pressure, however, has resulted in weed species that have adapted for survival—weeds have evolved to resist herbicides and the problem is now growing worse.
The new paper from CAST, Herbicide-resistant Weeds Threaten Soil Conservation Gains: Finding a Balance for Soil and Farm Sustainability, examines the impact of weed management practices on soil conservation and addresses ways to mitigate negative effects. The authors are Iowa State University Extension weed scientist Mike Owen; David Shaw, Mississippi State University; Stanley Culpepper, University of Georgia; Andrew Price, National Soil Dynamics Lab; and Robert Wilson, University of Nebraska.
A look at conservation programs in relation to herbicides and tillage
The U.S. government has put several federal policies and programs in place that help determine selection and use of crops and conservation programs in relation to herbicides and tillage. The authors of this paper discuss those program with regard to disagreement among organizations, there being no simple solutions. They also discuss the need for collaboration among all parties and they look at a case study of Palmer amaranth, "one of the most high-profile problems" in Georgia cotton.
The balance between conservation tillage and herbicide-resistant weed management is the central issue. As the authors state, "The fundamental conflict facing many farmers with herbicide resistance weed management issues today is the choice between using tillage or land stewardship practices that protect soil and water resources."
Weed resistance problem is only going to get worse unless action is taken
A few of the paper's conclusions: soil conservation is threatened by herbicide resistant weeds; growers are including and/or intensifying tillage practices because of resistant weeds; education programs are needed to show how resistant weeds can be managed without losing recent gains; more research is necessary regarding resistant weed management and conservation goals.
The full text of Issue Paper 49 may be accessed free of charge on the CAST website at www.cast-science.org, along with many of CAST's other scientific publications. The paper also is available in hard copy for a shipping/handling fee. CAST is an international consortium of scientific and professional societies, companies, and nonprofit organizations. It assembles, interprets, and communicates credible science-based information regionally, nationally, and internationally to legislators, regulators, policymakers, the media, the private sector, and the public.