Development and Evaluation of Bio-Cultural Weed Management Systems for Low-Till Grain Production
The goal of this project was to reduce the financial and environmental costs of weed control in corn and soybeans. We targeted conventional growers, those least likely to adopt organic methods and those using the most toxic herbicides. Our first objective was to develop and evaluate weed management practices that satisfy two conflicting environmental goals: reducing chemical inputs without increasing soil erosion that comes with intensive plowing and cultivation. Next, we tested various weed management practices on farms. Our third objective was to disseminate results of this research.
We conducted studies to determine how to get the most out of cultural practices like cover crops, modified row spacing and high residue cultivation to control weeds. Studies were designed to answer questions asked by grower cooperators: what is the time and seeding rate for hairy vetch? how far can herbicide rates be reduced before yields are affected? These and similar questions were studied in replicated, randomized experiments on the university farm so that growers would not have to sacrifice production in treatments that might be ineffective. To test alternative practices in real farm situations, growers set goals for economic or environmental changes they wanted to make on their farms. Growers were interested in reducing costs and negative environmental impacts of weed control, but were not willing to sacrifice production. Findings were disseminated at an integrated crop production field day.
We found several effective ways to reduce or eliminate the use of the most toxic herbicides with little increased risk of soil erosion. For growers familiar with herbicides, the easiest way to reduce potential environmental impact was to switch to safer products. Further reductions in herbicides were achieved by banding and high-residue cultivation. Using this system with reduced rates allowed us to reduce herbicides 85 to 95 percent. More important than simply decreasing herbicide use was the large reduction in environmental impact. A small grains cover crop helped suppress weeds in soybeans, but hairy vetch was less effective in suppressing weeds in corn. Grower cooperators identified the goal of reducing or eliminating high-rate residual herbicides as an environmental as well as an economic decision. Water quality and herbicide drift were important reasons for altering weed control practices.
The field day was attended by about 50 growers. Results of this project are being used to develop a section on nonchemical weed control methods for the Weed Control Guide. We are also developing a web page about weeds and weed management in Ohio. We have prepared a draft manuscript discussing the environmental and health risks and benefits associated with alternative weed management practices. One of the most important results of this project is that the relationship between researchers and growers has continued and we are now exploring low input approaches to management of perennial weeds. North Central Region SARE 1997 Annual Report.