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SWEEP Report #32

Optimal Herbicide Use in Conservation Tillage Systems

Researchers: 
J.E. Shaw, Ridgetown College of Agricultural Technology, Ridgetown, Ont. C.J. Swanton, V.S. Malik, Dept. of Crop Science, University of Guelph, Guelph, Ont.

Executive Summary

Evaluation Summary (Tech. Transfer Report Summaries)

View / Download Final Report [340 KB PDF]

Associated SWEEP/LSP Research

 

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Completed: August, 1991

Key Words:

cover crops, conservation tillage, corn, soybeans, winter wheat, herbicide, burndown, quackgrass, no-till, weed control, ridge till, fuel, labour, returns, risk, economics, banding, inter-row cultivation, chisel plow, conventional, Tillage 2000

Executive Summary

The goal of this study was to develop weed control recommendations for farmers utilizing conservation tillage systems. Efforts were directed towards optimizing herbicide selection, dosage and timing of application in order to achieve effective weed control. Moreover, research was also conducted to optimize herbicide inputs by developing an integrated weed management system for no-till corn. An economic and risk management study of weed control measures was also completed.

The results of this study will provide weed control and specific crop recommendations for farmers using conservation tillage. This information will facilitate the acceptance of conservation tillage practices within the Ontario farming community.

Field experiments were conducted from 1987 to 1990 to address the specific objective outlined in this report. Our findings included:

  1. Currently recommended herbicides and herbicide combinations provided excellent broad-spectrum weed control in all tillage systems tested.
  2. Control of weeds in conservation tillage systems did not require higher dosages of herbicides despite the presence of crop residue on the soil surface.
  3. Perennial weeds can be effectively controlled and should not pose a significant threat to successful crop production in conservation tillage systems.
  4. The integration of banded herbicide applications, inter-row cultivation and reduced herbicide dosage can be integrated as a weed control alternative for no-till corn . Adoption of these practices can reduce the total amount of herbicide applied into the environment by 60%.
  5. An economic comparison of alternative tillage systems and weed control practices among various tillage systems was completed. Optimum preemergence herbicide applications were identified for both corn and soybeans grown under four different tillage systems. The reductions in labour associated with the reduced tillage systems indicated that labour costs were reduced by up to 61% annually when compared with an conventional tillage systems. This saving in labour was illustrated as an opportunity cost associated with reduced tillage systems on sandy soils. A sensitivity analysis between moldboard plough and no-till indicated that no-till will dominate in risk preferring individuals, and an increase in no-till net farm returns of $40/ha would change dominance in favour of no-till among risk averse individuals. It is possible for conservation tillage systems to dominate conventional tillage systems, if proper weed control and crop production techniques are undertaken.

 

Evaluation Summary

(From Technology Transfer Report Summaries - A. Hayes, L. Cruickshank, Co-Chairs)
The goal of the study was to develop weed control recommendations for farmers using conservation tillage systems. Research was also conducted to optimize herbicide inputs by developing an integrated weed management system for no-till corn. The following are the studies conducted under each of the six objectives:
  1. Burndown and Residual Herbicides for Legume and Cereal Cover Crop Planted to Corn and Soybeans

    The following field experiments were done to study the effectiveness of various herbicides for burndown of cover crops:

    1. established alfalfa burndown in no-till soybeans
      • glyphosate (tank-mixed with metolachlor, metribuzin, linuron, dicamba or 2,4-D LV ester and amine) and amitrole-t (with linuron or metribuzin) were tested at various rates.
      • most provided good to excellent control of alfalfa, quackgrass and some other weeds.
    2. winter wheat cover crop control in soybeans
      • DPX Y6202-31, glufosinate, glyphosate and paraquat were tested, linuron and metolachlor were applied as preemergence to soybeans
      • glyphosate and paraquat provided excellent season long control of winter wheat seedlings
      • DPX Y6202-31 and glufosinate provided variable control
      • excellent annual weed control was provided by linuron and metolachlor
    3. winter wheat burndown with glyphosate
      • glyphosate was applied at four rates to control established winter wheat
      • later stages of wheat growth required higher rates of glyphosate
    4. red clover burndown in corn
      • most treatments provided good control of red clover
      • atrazine or metolachlor without a burndown did not provide sufficient control
    5. established alfalfa control in no-till corn
      • glufosinate plus atrazine was most consistent in controlling alfalfa and quackgrass
      • control of quackgrass and alfalfa varied with other treatments
    Recommendations based on the above experiments are provided.

     

  2. Antagonism of Burndown Herbicides with Residual Herbicides in Conservation Tillage Systems
    1. paraquat and glufosinate antagonism with residual herbicides in no-till corn
      • paraquat, glufosinate and metolachlor plus atrazine or cyanazine plus additives provided excellent weed burndown
    2. glyphosate antagonism with residual herbicides in no-till corn
      • glyphosate was applied at four rates to evaluate the potential for antagonism when tank-mixed with atrazine or cyanazine, residual herbicide metolachlor was applied to all treatments
      • burndown of annual weeds was not affected with the above combinations but burndown of weeds was affected when dicamba replaced atrazine or cyanazine
    3. paraquat and glufosinate antagonism with residual herbicides in no-till soybeans
      • paraquat and glufosinate were tank-mixed and applied separately with metolachlor, metribuzin, linuron, chloramben or metobromuron
      • excellent weed burndown was recorded on all treatments except paraquat plus chloramben or linuron plus oil
    4. glyphosate antagonism with residual herbicides on no-till soybeans
      • glyphosate was applied at four rates to evaluate the potential for antagonism when tank-mixed with metribuzin or linuron
      • glyphosate at lower rates when tank-mixed with metribuzin provided lower initial burndown as did glyphosate plus liquid or dry formulations of linuron
    5. compatibility of burndown and residual herbicides for quackgrass control
      • quackgrass control ratings are given for tank-mixes of glyphosate, paraquat or glufosinate with linuron, atrazine, metribuzin, metolachlor, 2,4-D amine, 2,4-D ester or dicamba
    Recommendations based on the above experiments are provided as is the performance of the residual herbicides.

     

  3. Impacts of Tank-mixes of Burndown and Residual Herbicides with Additives on Weed Control in Conservation Tillage Systems
    1. the role of additives with residual herbicides in corn
      • the additives tested when used with different herbicides provided excellent initial weed burndown and excellent season long control of grassy and broadleaf weeds
      • excellent initial burndown and subsequent weed control were facilitated by fertilizer based additives, however there were some escapes
    2. herbicides for burndown and residual control of annual weeds in no-till corn
      • residual herbicides provided satisfactory to excellent burndown of annual and perennial weed species, satisfactory to excellent control of emerging broad-leaved weeds and excellent control of late emerging grasses
    3. annual weed control in no-till corn by residual herbicides applied with additives
      • all treatments provided excellent annual weed control the first year but results were variable the second year
      • additives had no impact on weed control
    4. burndown and residual weed control in soybeans
      • excellent weed burndown was achieved by various combinations of herbicides in this experiment
      • results varied for broad-leaf and grassy weed control
    5. annual weed control in no-till soybeans by residual herbicides applied with additives
      • weeds escapes varied with herbicide used
    6. preemergence and postemergence herbicides for control of quackgrass
      • spring applications of glyphosate or quizalofop gave better quackgrass control than fall applications but glyphosate gave better season long control
      • glyphosate or quizalofop as pre-harvest applications had better early season quackgrass control than post-harvest
    Recommendations based on the above experiments are provided.

     

  4. Integrated Weed Management in No-till Cropping Systems
    1. Tillage 2000: weed control under various tillage systems
      • there was no significant tillage by crop interaction on crop yield
      • corn yield losses due to uncontrolled weeds were greatest in the no-till system
    2. effect of tillage on control of quackgrass
      • fall tillage (moldboard or soil-saver) controls quackgrass better than spring tillage and moldboard gave greater control than the soil-saver
      • most of the rhizomes are found within the top 7.5 cm of the soil surface in no-till
      • reduced and no-till systems have an increased reliance on glyphosate for quackgrass control
    3. residual effect of 2,4-D on soybeans
      • field experiments were conducted to investigate the effects of 2,4-D applied prior to planting on soybean yields
      • no visible injury was observed from carry-over of 2,4-D on soybeans in either year of the experiment
      • there were no yield reductions in the first year
      • in year two soybean yields were significantly reduced on the same day if soybean planting or treatments where 2,4-D amine salts were sprayed one week prior to soybean planting
    4. the integration of banded herbicide applications and inter-row cultivation in no-till corn production
      • corn yield was equivalent regardless of whether herbicides were applied as a band or broadcast treatment at all sites
      • banding herbicides results in an approximate 60% reduction in herbicide use
    Recommendations based on the above experiments are provided.

    Note: Yield, herbicide rates and control information are provided for all experiments.

     

  5. Cost/Benefit Ratio and Associated Risk of Weed Control Strategies Under Various Tillage Systems
    1. economic comparison of alternate tillage systems under risk
      • conventional, chisel plow, ridge till and no-till systems on clay and sand soils were studied for 200, 400 and 600 acre farm sizes
      • a ranking of the systems was done on the basis of risk
      • ridge till system was generally the dominant tillage system for all farm scenarios considered but the limited source of ridge till yield data may unfairly weight this particular system
      • no-till systems on clay loam soils were more dominant in the risk preferring range
      • risk averse individuals would prefer the mouldboard or chisel plow on clay soils
      • ridge till and no-till were the dominant systems on sandy soils
    2. minimum costs of alternative tillage systems
      • conventional, chisel plow, ridge till and no-till systems on clay and sand soils were studied for 200, 400 and 600 acre farm sizes
      • total farm costs and machinery costs were higher for moldboard and chisel plow systems but variable costs were higher for the no-till and ridge till systems
      • annual labour costs were reduced by 61% for reduced tillage and by 26% during the critical spring period, opportunity costs for the savings in labour are calculated

Comments:

This is an excellent report that provides much needed information on weed control in conservation tillage. There is a lot of information in this report that warrants a closer look by those making herbicide recommendations. The herbicide recommendations at the end of each group of experiments are very useful. The economic studies provide some interesting information on the costs of the different tillage systems. The risk analysis is a different way of looking at what systems a farmer may choose.

Associated SWEEP/LSP Research

  • SWEEP Report #10 - An Economic Evaluation of Tillage 2000 Demonstration Plot Data (1986-1988)
  • SWEEP Report #11 - An Economic Evaluation of Tillage 2000 Demonstration Plot Data (1986-1989)
  • SWEEP Report #19 - Studies on the Control of Problem Weed Species in Conservation Tillage Systems
  • SWEEP Report #19A - Weeds of Corn, Soybean, and Winter Wheat Fields Under Conservation and No-Till Management Systems in 1988 and 1989.
  • SWEEP Report #48 - The Feasibility of Band Spray Application in Conjunction with Inter-row Cultivation in No-Till Corn.

Future Research: ( ) indicates reviewers suggestion for priority, A - high, C - low.

(A) Some of the studies could use another year or two to verify the results.

 

 

 

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Created: 05-28-1996
Last Revised: Thursday, May 19, 2011 02:50:17 PM