The Slimy Corn Plant That Is Helping Fight Climate Change

In the last 100 years, the world population has quadrupled from two to eight billion people. Feeding all those people is one of the biggest challenges we face as a civilization. Fortunately, nature and scientific advances are continuously discovering new ways to keep the planet nourished. But, for how much longer?

How Nitrogen Changed The World

From the beginning of civilization, farmers have been finding ways to fertilize their fields and increase their crop yields. Typically that fertilization came in the form of animal and human waste products. Farmers knew that their crops needed nutrients, but it wasn’t until 1840 that scientists made the important link to find that nitrogen was the primary chemical necessary for farming. 

While farmers could grow a modest crop on their own, the kind of large-scale farming necessary to feed the world just wasn’t possible until 1913 when the Haber-Bosch process was discovered.

The Haber-Bosch process is a procedure that takes nitrogen from the air and converts it to ammonia that’s used to produce synthetic fertilizers on a mass scale. It’s estimated that crop yields more than doubled between 1908 and 2008, with synthetic nitrogen fertilizer from the Haber-Bosch process responsible for up to half that growth. 

Synthetic fertilizer is a major contributing factor to the massive human population growth over the last seventy years.  Without it, there would not be sufficient food to support billions of people across the world.

The Dark Side Of Synthetic Fertilizer 

While synthetic fertilizer helps grow the food that sustains billions of people, its production comes at a heavy cost. Between 1 to 2 percent of the world’s energy is used via the Haber-Bosch process. 

When synthetic fertilizer is created, greenhouse gases are emitted and nitrogen is washed off fields into waterways, causing oxygen-sucking algae to bloom and killing sea life. Enormous dead zones have developed in rivers around the world, including one in the Gulf of Mexico that was the size of New Jersey. 

So, what’s the answer? Cutting back on synthetic fertilizer would leave billions of people without enough food, but continuing to produce it is destroying the earth.

What if we could get plants to produce their own nitrogen?

While this may sound like a far-fetched solution, the truth is that it’s already happening! Rhizobium is a type of bacteria that has a symbiotic relationship with many different plants like soybeans and peanuts. The bacteria live in root nodules where they ingest the plant’s sugars while converting nitrogen in the air into a form the plants can use. 

The problem is that, while these plants are useful, cereal crops like corn and wheat are the primary sources of food needed to support the mass population growth the planet has had... and none of those cereal crops seemed to be able to produce their own nitrogen. Until recently…

What in the world is mucus corn?

In the 1980s, Howard-Yana Shapiro, now chief agricultural officer at Mars, Incorporated, discovered a peculiar type of corn called Sierra Mixe in southern Mexico. The corn grew to impressive heights…. Up to 16 to 20 feet tall in very poor soil!  But that wasn’t even the most remarkable thing about the Sierra Mixe corn. 

From top to bottom, the corn’s stalks were covered with strange green and rose-colored protrusions .  From each of these finger-like structures dripped a clear, syrupy gel. 

Shapiro suspected that the protrusions were actually aerial roots that allowed the corn to produce its own nitrogen. But, it took 20 years to prove that he was correct. In 2005, after extensive research, Alan B. Bennett of the University of California, Davis—along with Shapiro and other researchers— came to the conclusion that indeed, bacteria living in the mucus were pulling nitrogen from the air and transforming it into nutrition that the corn could absorb. 

While the results are similar, the process by which nitrogen is created in the Sierra Mixe corn is much different than in plants like soybean. Inside the mucus, microbes carry genes for fixing nitrogen which then makes its way into the corn, providing 30-80% of the plant’s needs.  The high-sugar, low-oxygen slime is the perfect environment to support the microbes in their nitrogen fixation. 

After extensive research, scientists discovered that the microbes would produce nitrogen in synthetically produced slime as well. They planted the Sierra Mixe corn around the United States, proving that it can grow outside of Mexico. 

Now what?

Now that scientists know that it’s possible for one type of corn to produce its own fertilizer, researchers are working on incorporating this nitrogen-fixing trait into conventional corn. Their success would have major worldwide implications. Cutting back on the need to create synthetic fertilizer would reduce the cost of farming, cut greenhouse gas emissions, and stop one of the major pollutants of waterways.

And that’s not all…

There are several other ongoing projects aimed at getting cereal and vegetable crops to do the Haber-Bosching for us. University of Washington researcher Sharon Doty has been researching the use of endophytes (microorganisms like bacteria and fungi that live in the intercellular spaces of plants) in creating fertilizer. 

Her tests have shown that the microbes can double the productivity of pepper and tomato plants, improve growth in rice, and make trees more resilient to droughts. Some types of microbes can even be used to allow trees and plants to suck up and break down industrial contaminants. 

“There [are] a whole slew of different microbes that can fix nitrogen and a broad range of plant species impacted by them,” Doty says. “The advantage of using endophytes is that it’s a really large group. We’ve found strains that work with rice, maize, tomatoes, peppers and other agriculturally important crop plants.”

While it’s unlikely that one solution alone will be able to completely replace synthetic production of fertilizer, the emerging research shows great potential in decreasing nitrogen pollution and making a big impact in the battle against climate change.