An alarming number of stories are appearing in the farm press about how Roundup-resistant weeds are forcing conservation tillage farmers to take a serious look at plowing up their fields—in effect throwing out years of soil building and soil protection with one pass of a steel shank. Nationally, such a return to the plow would represent a step backward, since no-till, ridge till and other methods for cutting the amount of soil that’s disturbed during planting have been on the increase since the 1990s. In Minnesota, however, herbicide resistance may be just one more reason conservation tillage just can’t quite get out of the starting blocks in the first place.
As of last summer, over 20 states, including Minnesota, had documented herbicide-resistant weeds. Glyphosate, the generic name for Roundup, is the herbicide weeds love to thumb their noses at the most. As a recent Associated Press article out of Illinois succinctly put it, herbicide resistance “stems in large part from overuse of the chemical.” In short, Monstanto’s Roundup Ready technology has made the use of the herbicide glyphosate so ubiquitous that superweeds are evolving. (Remind us again why a perennial GMO plant like Roundup Ready alfalfa —one that will increase the use of glyphosate herbicide even more—is a good idea?)
As we’ve discussed in this blog previously, Roundup resistant weeds are bad news for a lot of reasons, not the least of which is that it means farmers are being forced to return to some nasty pre-emergent weed killers—the same pre-emergents Roundup was supposed to help us avoid. That’s not only bad for the environment and human health, but can be hard on a farmer’s bottom line. Re-treating crops after herbicide resistance has been discovered in a field can cost $20 to $30 extra per acre, according to one estimate.
Pile on top of that recent findings from scientists like Don Huber that glyphosate significantly reduces nutrient availability and plant efficiency for a number of essential plant nutrients. Some of these changes are brought about by glyphosate’s direct toxicity, while others are brought about indirectly through changes in soil organisms. In other words, Roundup may be undermining the soil’s very ability to produce crops in the long term. (A former extension educator told me this week that after initially dismissing out-of-hand Huber’s work as “crazy,” a growing number of land grant scientists have given it a closer look—and are concerned he may be onto something).
Now Roundup may pose yet another threat to our soil—in this case affecting how much of it stays on our fields and out of our water. No-till cropping and Roundup Ready technology have become joined at the hip over the years. And for good reason: corn and beans genetically engineered to resist being killed by herbicide are a perfect fit for a system where mechanical weed control is not being used.
But when a mainstream ag publication like Progressive Farmer publishes an article outlining how superweeds have become such a threat that no-tillers are considering going back to deep plowing and other soil disturbance methods, it’s beginning to look like Roundup’s ride on the soil-saving bandwagon is about to come to a screeching halt.
This is the last thing the conservation tillage community needs right now. According to a recent USDA-Economic Research Service study, over 35 percent of U.S. cropland (88 million acres) planted to eight major crops is under a no-till system. For corn, soybeans, cotton and rice, no-till increased at a median rate of roughly 1.5 percentage points per year between 2000-2007.
These national trend lines are in the right direction, and are part of the reason erosion rates have gone down in many parts of the Corn Belt.
But a lot more work needs to be done if the majority of our farmland is to be no-tilled consistently season-after-season. The recent news about superweeds could undermine the confidence of even the most stalwart no-tiller, and will certainly make it hard to gain new converts.
That’s particularly true here in Minnesota, which has always lagged behind in the adoption of conservation tillage methods. As I wrote a decade ago, our wet soils and cold springs make conservation tillage a challenge here—exposing as much black soil to that May sunshine is very desirable after a snowbound Minnesota winter.
There have also been signs that farmers in Minnesota lack the technical support system need to adopt and maintain the most basic conservation tillage system. The Conservation Technology Information Center estimates it takes at least five years to adopt a conservation tillage system like no-till. A few unusually wet springs early on in that five-year transition can send a farmer back to the moldboard plow pretty fast.
“You can change hybrids, you can change herbicides, but this is different. Making a change in tillage is a fundamental change in your management system,” University of Minnesota soil scientist Gyles Randall once told me.
Indeed, the USDA’s latest estimate is that in 2006 only 11 percent of Minnesota’s soybeans were grown under a no-till system. Nationally, 45 percent of soybeans were grown under such a system that year.
For farmers who don’t want to return to the plow, there are alternatives to Roundup Ready technology. And no, those alternatives don’t always involve even more herbicides, as the chemical company agronomists would have us believe.
Diverse crop rotations and innovative use of cover crops and rollers offer exciting ways to save soil without relying on a cocktail of herbicides. But more research is needed into such systems. And since such systems won’t improve the bottom lines of companies like Monsanto, that kind of science needs to be publicly funded.