Optimal herbicide use in conservation tillage systems

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 broadspectrum 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 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 cost 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 intervals, and an increase in no-till net farm returns of $ 40 ha-1 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.