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Shrinking the Dead Zone, Reducing Fertilizer Use

By Bill Wenzel
Food and Farming Program Director

Last week, scientists predicted that this year’s hypoxic zone in the Gulf of Mexico will be the 3rd largest since monitoring began 32 years ago. The “dead zone” will cover about 8,185 square miles — an area roughly the size of New Jersey. 

What’s a dead zone? It’s water that has insufficient oxygen to support marine life, in this case largely due to the overuse of nutrients and fertilizers in agriculture.   

The prediction of a super-sized hypoxic zone was based on monitoring data conducted last month, which estimated that during the month of May 2017 alone, 165,000 metric tons of nitrate — or 2800 train cars full of fertilizer — and 22,600 metric tons of phosphorous flowed down the Mississippi River into the Gulf of Mexico.

And midwesterners are beginning to experience “dead zones” of their own as toxic algae blooms close parks and beaches to summertime vacationers and pose increasing risks to drinking water and public health. While there are contributors other than nutrient pollution, it is the large cropping systems that grow corn and soybeans year after year that are responsible for much of the problem. Synthetic fertilizers and other agrochemicals are increasingly needed to maintain crop productivity on farms that grow only corn and soybeans, and the deadly cycle repeats itself annually.

There is a solution - crop diversification. Before the advent of factory farms and GMO technology, most farms were diversified. Farmers grew a variety of crops for food and feed and typically had livestock and poultry. Industrialized agriculture has led to concentration, vertical integration and specialization, but diversification is making a comeback.

Dr. Matt Liebman, ISU Agronomy Professor and Sustainable Ag Chair, has been conducting crop system research since 2003 on diversifying crop rotations with the goal of balancing profitability with environmental and the public health impacts

Dr. Liebman’s research has demonstrated that it is possible to reduce the use of synthetic fertilizers and pesticides by up to 90% by incorporating a small grain (i.e. oats) and a cover crop into a typical corn-soybean rotation.  This one change in farming practices, has the potential to virtually eliminate the use of synthetic fertilizers and pesticides.  

As Dr. Liebman puts it,”more diverse cropping systems can use small amounts of synthetic agrichemical inputs as powerful tools to tune, rather than drive agroecosystem performance.”

We as consumers can play an important role in using our power in the marketplace to promote crop diversification. Currently, there isn’t a market for the small grains grown in Dr. Liebman’s system, although oats and other small grains could easily provide an alternative feed source to corn in livestock and poultry production.   

Consumers are increasingly favoring sustainability. Consider the growth in organics, or the fact that restaurants are cutting antibiotics out of their meat production to please consumers. Likewise, consumer pressure to encourage adoption of crop diversification practices may be needed to drive industry acceptance.

And in the policy arena, with the 2018 Farm Bill debate beginning to heat up, decision makers would be wise to consider ways to incentivize and/or require the use of crop diversification practices.

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