Farmers in a small area of southern Mexico knew that a variety of corn grown in the area was special.
But a group of researchers believe the corn could ultimately transform the way the largest crop in America and the world is grown.
The potential improvements in water and air quality – not to mention financial savings – are staggering. In fact, the lead researcher acknowledged he and his colleagues spent a decade studying the corn before going public this month because the conclusions were “almost outrageous.”
And, like so much research in its early stages, there are still a lot of “ifs.”
But scientists at University of Wisconsin-Madison, University of California-Davis and Mars Inc. (yes, the candymaker) have determined that farmers in Oaxaca, Mexico, have been growing corn that creates its own fertilizer for centuries, if not millennia.
Understanding the process requires a short course in biology.
The plants in Mexico have bizarre fingerlike roots sticking out of their stalks. The roots secrete a goopy mucus, in which bacteria live. The bacteria take nitrogen from the air – which plants can’t use – and convert it to a different form of nitrogen that they can use. The plants soak up the fixed nitrogen in the gel through the fingerlike roots.
The nitrogen is a critical nutrient for all plants; it’s the primary ingredient in chemical fertilizers.
The process is part of a cycle. The bacteria live on carbon, which the plant supplies in the form of sugar. The sugar is produced through photosynthesis. Through this odd trade agreement, the plant gets usable nitrogen, the bacteria get necessary carbon and both parties are happy.
Nitrogen fixation is best known for occurring in legumes like soybeans. The bacteria live in their roots and the surrounding soil. But this had not been demonstrated in grasses like corn.
A decade of research
The researchers found out about the corn from Howard-Yana Shapiro, the chief agricultural officer at Mars and adjunct professor at UC-Davis. Decades ago, he had the idea to look for unusual traits in crops that traditional farmers have adapted to their particular climate and soil. He hoped to find something that could improve crops globally.
When Shapiro came across 16-foot-tall cornstalks growing on an Oaxacan mountain slope where nutrient levels and fertilizer availability should have been low, he knew they deserved a closer look.
Jean-Michel Ané, professor in the UW-Madison Department of Agronomy, has been involved in the project since 2010. “They came to me and asked if I thought it was possible that corn could be associated with nitrogen-fixing bacteria, and I thought, no way.”
The research group first collected samples from cornfields in the Sierra Mixe area of Oaxaca in 2010. When they noticed the goopy aerial roots, “We were like, that’s weird,” Ané said.
They tested the goopy gel, and it tested positive for one of the byproducts of the nitrogen fixation process.
But that alone didn’t prove the plant was getting nitrogen from the bacteria instead of the soil, Ané said. The researchers ran tests from every angle they could think of: Are any of the bacteria found in the gel known nitrogen-fixers? Does the corn soak up less nitrogen from the soil than a similar, non-nitrogen-fixing variety? Does the corn for sure soak up nitrogen from the gel?
The answers were yes, yes and yes.
“It took us several years to convince ourselves that it was true. That’s why it took us almost 10 years to publish that paper. It’s a big claim. We wanted to be sure,” Ané said.
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Source: USA Today