Development and Evaluation of Bio-Cultural Weed Management Systems for Low-Till Grain Production

Project Overview

ANC94-023
Project Type: Research and Education
Funds awarded in 1994: $0.00
Projected End Date: 12/31/1997
Matching Non-Federal Funds: $114,322.00
ACE Funds: $58,183.00
Region: North Central
State: Ohio
Project Coordinator:
John Cardina
Ohio State University

Annual Reports

Commodities

  • Agronomic: corn, rye, soybeans, wheat

Practices

  • Crop Production: conservation tillage
  • Education and Training: demonstration, on-farm/ranch research
  • Pest Management: chemical control, competition, cultural control, integrated pest management, mulches - killed, physical control, cultivation, precision herbicide use, weed ecology
  • Production Systems: agroecosystems
  • Soil Management: soil quality/health

    Abstract:

    [Note to online version: The report for this project includes tables and figures that could not be included here. The regional SARE office will mail a hard copy of the entire report at your request. Just contact North Central SARE at (402) 472-7081 or ncrsare@unl.edu.]

    Objectives: The overall 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 often conflicting environmental goals: reducing chemical inputs without the increased soil erosion that comes with intensive plowing and cultivation. Next, we tested various alternative weed management practices on cooperating growers’ farms. Our third objective was disseminate results of this research through scientific publications, grower meetings, and a field day.

    Methods: To develop weed control practices that minimize herbicides as well as soil erosion, we conducted component 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. The specific studies were designed to answer questions asked by grower cooperators, such as: what is the time and seeding rate for hairy vetch?, and 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 the 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 that addressed the many trade-offs involved in trying to achieve optimal crop productivity without inflicting environmental damage.

    Results: 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 simply 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%. More important than simply decreasing herbicide use was the large reduction in potential 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.

    Impact: The integrated crop management 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 Ohio Weed Control Guide. We are also developing a web page about weeds and weed management in Ohio to address issues about this project as well as a summary of our data. 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.

    Introduction:

    The goal of this research was to reduce the environmental impact of weed management systems without compromising grain production or increasing risk of soil erosion. Studies were conducted on growers’ fields and in small plots to develop and evaluate integrated management systems that reduce chemical inputs and costs of weed control. Cover crops, mechanical cultivation, and alternative herbicide technologies were used to reduce residual herbicide and fertilizer inputs. Reduced environmental impact of herbicides was achieved by reducing rates of standard herbicides and use of lower toxicity herbicides at reduced rates. Cover crops and row cultivation were used in and effort achieve effective weed control with reduced herbicide rates. A hairy vetch cover crop contributed significant nitrogen and suppressed early season weed growth. The combination of a cover crop with banded and low-rate herbicide applications reduced herbicide use without resorting to tillage practices that make soil vulnerable to erosion. Obstacles to the use of hairy vetch were the high cost of seed and the need for early establishment. Studies showed that optimum planting dates were from early to late August, and surface sowing was only successful if a rain immediately followed seeding. Although the effectiveness of cover crops for weed control was low and restricted to early season weeds, their value for soil cover and erosion reduction was high. A no-till cultivator was effective when herbicides were banded over the crop row; acceptable weed control was achieved with a reduction in herbicide rates up to 85%. Using an index to compare the environmental impact of various herbicides, the least potential negative impact for corn was for systems that had a hairy vetch cover crop plus banded applications of the herbicide imazethapyr at reduced rates with a no-till cultivator. For soybeans, the lowest potential negative impact was for a system with a small grain cover crop and postemergence applications of a half-rate of theifensulfuron plus chlorimuron plus quizalifop. In soil erosion and water runoff experiments, postemergence herbicide concentrations in surface water were 100 to 300 times less throughout June than concentrations of standard soil applied herbicides. 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. Economic analysis showed a cost disincentive for reducing environmental risk due to higher prices for lower toxicity herbicides and the need for additional field operations compared with herbicide-only programs. A field day, attended by about 50 growers, addressed environmental and economic trade-offs associated with alternative management strategies, and demonstrated ways to integrate cover crops and rotations systems. Results are being used to prepare a discussion of nonchemical weed control methods for the Ohio Weed Control Guide and for a web page dealing with weeds and weed management in Ohio.

    Project objectives:

    Develop and evaluate integrated bio-cultural weed management systems that reduce chemical inputs and costs of weed control in low-till grain production.

    Implement a goal-setting approach for on-farm testing and evaluation of alternative weed management systems through a collaboration of producers, researchers, and extension personnel.

    Disseminate results of collaborative research through scientific, extension, and popular publications, grower meetings and field days.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.