Monochemicals + Monocrops = Mucho Problems

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The National Research Council’s announcement this week that “genetically engineered crops benefit many farmers” and is in general good for the environment came with a big fat caveat: overuse of GMO products like Roundup Ready corn and soybeans threatens to undermine any potential benefits while creating unforeseen problems. That’s why the scientists who authored the NRC’s report fell back on the tried-and-true “more research is needed” conclusion to cover themselves. It certainly is—just consider the recent news that the herbicide glyphosate (a linchpin in the Roundup Ready system) is threatening the soil’s ability to create a healthy growing medium for crops. That’s not just a regrettable side effect that puts a bit of a tarnish on a silver bullet—it’s a potential bombshell that changes everything farmers (and environmentalists) have been led to believe about this ubiquitous herbicide.

This blog has previously described the problem of how overuse of Roundup Ready technology is creating strains of superweeds that can’t be killed by glyphosate. In fact, the NRC report documents that at least nine species of weeds have evolved resistance to glyphosate since genetically engineered crops made their appearance in U.S. farm fields 14 years ago. The result is increased applications of herbicides that are are much nastier for the environment than glyphosate supposedly is (more on the “supposedly” qualifier later). We’ve also reported on studies that put the NRC’s somewhat overall rosy assessment of GMOs’ economic benefits in perspective.

Up until now, much of the discussion around Roundup Ready GMO technology has been based on the belief that glyphosate is safer for the environment than many of the pre-emergent herbicides it was supposed to replace. This is based on the idea that its greater volatility in the environment makes it less likely to hang around long enough to create environmental and human health problems. So, goes the argument, applying more glyphosate is less of a threat than applying less atrazine, for example.

But Don Huber has thrown a monkey wrench into this mindset. Huber, a Purdue University emeritus professor of plant pathology, has recently been making minor waves within the world of no-till/minimal till agriculture by highlighting glyphosate’s ability to make the growing environment for plants an unhealthy one. In a summary paper of the latest research in this area, Huber documents how glyphosate has significantly changed 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.

It seems one of the indirect effects of glyphosate is that it ties up or “chelates” the micronutrients necessary for healthy plants. For example, it can consistently inhibit plant enzymes responsible for disease resistance, making corn and soybeans more vulnerable to pathogens. It does this to plants engineered to resist being killed outright by glyphosate, as well as their non-GMO counterparts.

Huber’s 13-page paper has this chilling conclusion: “The introduction of such an intense mineral chelator as glyphosate into the food chain through accumulation in feed, forage, and food, and root exudation into ground water, could pose significant health concerns for animals and humans and needs further evaluation.”

Huber is a widely respected plant pathologist at Purdue University, not a weed-hugger from Berkeley. His warnings are being taken seriously by a sector of the farming community that the NRC highlights as benefiting greatly from Roundup Ready technology: no-till and minimum-till farmers. In an effort to reduce tillage-based weed control as much as possible, these types of crop producers have adopted glyphosate-resistant plant technology in droves.

But in an article tellingly called “Are We Shooting Outselves In The Foot With A Silver Bullet?”, the March issue of No-Till Farmer magazine quotes Huber and other researchers who are quite concerned that Roundup Ready is becoming a detriment to crop farming. It turns out farmers and crop consultants are reporting more incidents of entire fields of crops showing signs of disease and stress in general. They may not die outright, but will do things like mature earlier, turning yellow and losing the bright green coloring that shows they are still adding to their final yield. The plants don’t die outright, but they sure get sick. And sick plants don’t produce bumper crops.

“For the last 2 to 3 years, corn plants have been losing color about 7 to 10 days earlier each year,” Iowa crop consultant Bon Streit told No-Till Farmer. “In 2009, we often saw corn yellowing up by August 1 even where nitrogen deficiencies weren’t the problem.”

Up until now, such signs of stress were automatically blamed on weather or some other “outside” culprit. But Huber and others are now saying no-till and minimum-till farmers need to look at their own spray tanks as a source of problems.

Perhaps the most troubling point that Huber makes is that contrary to conventional wisdom, glyphosate is not a temporary presence in the environment. It can actually stick around in the soil for long periods of time, and this is a problem.

“We see a buildup of glyphosate in the soil in part from glyphosate-tolerant crops and weeds,” Huber told No-Till Farmer. “When we add phosphate fertilizers for corn, soybeans or wheat, for example, the phosphorus reacts to release the glyphosate back into the soil, where it’s available for uptake by plants.”

And that build-up, along with the negative results of that build-up, gets worse over the years. One German study found that wheat planted in soil where glyphosate had been used for a decade yielded 46 percent less than wheat planted where glyphosate had been used for only a year. And since no-tillers disturb the soil less, they are at greater risk of seeing the herbicide accumulate to levels where crops will be negatively affected.

Perhaps it’s no surprise that a monochemical weed control system has created some major biological problems within our crop fields. After all, monocultural cropping in general has turned out to be a tremendously bad idea rife with unforeseen pitfalls.

But what is surprising is that so little research into this area has been done here in the U.S., where 80 percent of our corn, soybeans and cotton are now genetically engineered. And yet, much of Huber’s summary paper relies on research that was reported in foreign scientific publications. Even when research on this subject is done in this country, much of it tends to be published in Europe.

“Why did the Missouri authors publish in an European journal?” one Iowa crop and livestock farmer wrote me in an angry e-mail after he had read Huber’s paper. The farmer was referring to one Huber-cited study that was done in the Show-Me state on  glyphosate’s promotion of soybean disease. “I find the articles incredible in that they’re absolutely turning on its head everything farmers and the public have been told about Roundup,” continued the farmer.

He’s right. But research that unearths bad news about GMO crops tends not to fare well when published in this country. Consider the fate of Emma Rosi-Marshall when her paper on Bt corn and how it could have negative effects on stream ecosystems was published in the Proceedings of the National Academy of Sciences in 2007. As an article in Nature documented last fall, the GMO community wasn’t satisfied with just dismissing Rosi-Marshall’s research or proving it wrong—the battle got quite personal. Maybe U.S. researchers (and U.S. journals) are a little gun-shy about stinking up the GMO party. That may be even more true now that the NRC has given the technology a (qualified) green light.

That’s too bad, because as the NRC report and Huber’s paper makes clear, we need research on the long-term effects of GMOs now more than ever. And we’re upping the ante by the minute. Consider this: the USDA is now considering whether to approve use of Roundup Ready alfalfa in this country. A perennial crop that can be sprayed with glyphosate? If that isn’t a recipe for overuse of an already abused chemical, I don’t know what is.

As my farmer friend concluded in his e-mail: “I’m still seething.”

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