Challenges and Opportunities for Weed Management in No-Till Farming Systems

Abstract

Tillage has been used as a major weed management tool for several decades in conventional agricultural systems; however, it has also presented problems, such as degradation of soil health and high production costs. Therefore, a trend towards the adoption of no-till (NT) systems has emerged over recent decades. With the adoption of NT systems has come the elimination of a key component (tillage) of weed management strategies, resulting in a shift in weed dynamics across agricultural systems. Weed management is a challenging component of a successful NT system wherein the use of herbicides have become the most prevalent control method. This over-reliance on chemicals is not a sustainable long-term strategy as it imposes a high selection pressure on weeds, drives the problematic evolution of herbicide-resistant weeds, pollutes the environment, and causes health hazards. The use of biotechnology to develop herbicide-tolerant crops, such as those tolerant to glyphosate, has undoubtedly revolutionized the adoption of NT systems. However, many issues concerning human health and the development of weeds resistant to herbicides are arising as a result of the use of these crops. A recent ban on the use of glyphosate in a few countries may lead to further restrictions on the use of herbicide-tolerant crops, potentially resulting in a reverse in course from NT production systems to more conventional tillage systems. Therefore, the task of evaluating alternative weed management strategies with respect to NT systems presents challenges. Techniques designed to reduce competitiveness in weeds or enhance competitiveness in crop plants while reducing dependency on herbicides, such as modifying row spacing and orientation, adjusting planting density and sowing time, and use of competitive cultivars, mulching and cover cropping have been developed by agricultural scientists. Modified or strategic tillage and crop diversification are other potential strategies which can be used for weed management in NT systems. Potential non-conventional weed management strategies such as harvest weed seed control, allelopathy and precision weed management using remote sensing and robotics require further evaluation for their feasibility, efficiency and viability in these systems. This chapter highlights possible combinations of non-chemical, non-conventional and chemical weed management tools that can be used in an integrated weed management approach, presenting the potential for a favorable shift in the crop-weed balance in NT systems.