“Anything you put on the land affects the chemistry and biology of the land, and that’s a powerful pesticide,” Iowa farmer Dennis Von Arb said. http://www.nytimes.com/2013/09/20/business/misgivings-about-how-a-weed-killer-affects-the-soil.html?ref=us His neighbor grows “traited,” or biotech, corn and soy on some 1,500 acres and estimates that his yield would fall by 20 percent if he switched to conventional crops and stopped using glyphosate, known by brand names like Roundup and Buccaneer.
Biotech crops currently account for roughly 90 percent of the corn, soybeans and sugar beets grown in the United States.
While regulators and many scientists say biotech crops are no different from their conventional cousins, others worry that they are damaging the environment and human health. The battle is being waged at the polls, with ballot initiatives to require labeling of genetically modified foods; in courtrooms, where lawyers want to undo patents on biotech seeds; and on supermarket shelves containing products promoting conventionally grown ingredients.
Now, some farmers are taking a closer look at their soil.
First patented by Monsanto as a herbicide in 1974, glyphosate has helped revolutionize farming by making it easier and cheaper to grow crops. The use of the herbicide has grown exponentially, along with biotech crops.
The pervasive use, though, is prompting some concerns.
Critics point, in part, to the rise of so-called superweeds, which are more resistant to the herbicide. To fight them, farmers sometimes have to spray the toxic herbicide two to three times during the growing season.
Then there is the feel of the soil.
Dirt in two fields around Alton where biotech corn was being grown was hard and compact. Prying corn stalks from the soil with a shovel was difficult, and when the plants finally came up, their roots were trapped in a chunk of dirt. Once freed, the roots spread out flat like a fan and were studded with only a few nodules, which are critical to the exchange of nutrients.
In comparison, conventional corn in adjacent fields could be tugged from the ground by hand, and dirt with the consistency of wet coffee grounds fell off the corn plants’ knobby roots.
“Because glyphosate moves into the soil from the plant, it seems to affect the rhizosphere, the ecology around the root zone, which in turn can affect plant health,” said Robert Kremer, a scientist at the United States Agriculture Department, who has studied the impact of glyphosate on soybeans for more than a decade and has warned of the herbicide’s impact on soil health.
Like the human microbiome, the plants’ roots systems rely on a complex system of bacteria, fungi and minerals in the soil. The combination, in the right balance, helps protect the crops from diseases and improves photosynthesis.
Several years ago, Mike Verhoef switched to biotech corn and soybeans on his 330 acres in Sanborn, Iowa. He regularly rotated the two crops with oats, which are not genetically engineered, to help replenish the nutrients in the soil.
Almost immediately, he said problems emerged. He noticed that his soil was becoming harder and more compact, requiring a bigger tractor — and more gas — to pull the same equipment across it. The yield on his oats also dropped over time by about half.
“It took me that long to figure out what was going on,” Mr. Verhoef said. “What I was using to treat the traited corn and soy was doing something to my soil that was killing off my oats.”