I wanted to share a link today to a paper published by CAST, the Council for Agricultural Science and Technology. This paper, entitled "Herbicide-resistant weeds threaten soil conservation gains: finding a balance for soil and farm sustainablity", was released about a year ago and addresses one of the less obvious issues resistance imposes - soil erosion. This paper can be viewed or downloaded (free!) at the link above.
The development and adoption of effective postemergence herbicides, both conventional and GMO-linked, has resulted in tremendous gains in soil conservation for much of the country due to the reduction in "clean" tillage, in-season cultivation to control weeds, and tillage operations to incorporate soil-applied herbicides. This is of particular benefit in regions with summer rain, intense winds, and varied topography (like much of the Midwest where I'm from) but it benefits California growers and citizens too.
I won't attempt (in a Friday afternoon blog post) to repackage the careful assessment and explanation written by Shaw, Culpepper, Owen, Price, and Wilson. I'd encourage you to read through the article for a slightly different view of the complex issues and cost/benefit considerations made by weed managers. In the CAST paper, the issue is largely soil erosion from water but here in California, you might be more likely to consider dust (PM10). I'd offer the point that weed management considerations are full of trade offs - economics, time, environmental; non-chemical weed control efforts are not without problem.
Brad
CAST Abstract. (Shaw et al. 2012)
Tillage has been an integral part of crop production since crops were first cultivated. Growers and scientists have long recognized both beneficial and detrimental aspects of tillage. There is no question that most tillage operations promote soil loss, adversely affect (lower) surface water quality, and negatively impact soil productivity. Weed management is a primary reason for tillage, and until the development of highly effective herbicides, conservation tillage was not feasible. Furthermore, with the development of herbicide-resistant (HR) crops, particularly glyphosate-resistant (GR) crops, herbicides such as glyphosate minimized the need for tillage as a weed control tactic; the resulting crop production systems have been primary enablers for the success of U.S. Department of Agriculture Natural Resource Soil Conservation programs.
