Human Practices

A Talking With Professor Mulvaney

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Dr. Mulvaney is a professor at the University of Illinois at Urbana-Champaign whose research focuses on reducing the negative effects of nitrate fertilizers by improving nitrogen uptake in crops. More information about Dr. Mulvaney can be found here .

We talked to Dr. Mulvaney in order to learn more about the source of nitrate N loss, the extent of its environmental impacts, and the challenges of addressing this global issue.

Dr. Mulvaney confirmed that the overuse of chemical nitrogen fertilizers (CNF) is the primary source of nitrogen (N) pollution. Part of this excess usage stems from caution - in order for farmers to avoid low crop yields, they are recommended to add enough fertilizer for 1.2 times their expected yield. However, it has been found that adding more N causes. Based on research done from our school’s Morrow Plots, it seems that natural soil fertility decreased with the addition of CNF [1]. This is especially problematic for cereal crops, since they do not have the natural ability to capture nitrate from the environment and turn it into bioavailable nitrogen (nitrogen fixation). This creates a cycle of excess CNF usage - less fertile soil creates lower yields, pushing farmers to add more CNF to increase yields.

But despite the evidence against the use of nitrate fertilizer, the fertilizer industry is unlikely to change for one simple reason: profit. The price of anhydrous ammonia fertilizer (the major component in CNF) is consistently higher than alternative sources, which motivates the advertisement and creation of this type of fertilizer (Figure 1).

Figure 1. Prices of anhydrous ammonia fertilizer compared to alternative fertilizers. Taken from [2].

We also talked to Dr. Mulvaney about how N pollution affects local communities. He directed our attention to Illinois’ Lake Decatur, which is discussed more below.

Integrated Human Practices

Lake Decatur

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After meeting with Professor Mulvaney, we decided to do independent research about how N pollution is affecting local communities so we could share this information to the surrounding community.

Lake Decatur supplies 39.4 million gallons of water a day to 87,000 people in Decatur and surrounding communities [3]. However, the water supplied from Lake Decatur has been deemed unsafe to drink due to high concentrations of nitrate (Figure 2).

Figure 2. Nitrate-N concentrations from 1920 to 2010 have been consistently above the maximum contaminant level (MCL) periodically since 1967. Taken from [3].

The high levels in Decatur result from nitrate leaching, the loss of nitrogen in agricultural systems. In recent years, there has been an increased demand for nitrate containing fertilizers. Though this has helped boost crop production, the excess nitrate in the soil has created negative environmental impacts.

Impact on Our Project

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We were already concerned about the issue of nitrate runoff since the surrounding community of U of I relies so heavily on farming cereal crops. However, through our talk with Professor Mulvaney, we realized that one of the major sources of this issue is profit motivation, which is not easily solvable. Since the fertilizer industry is extremely persistent and almost too large to fail, we believe our solution can serve to mitigate the negative effects of the CNF industry.

Previously, our project had only addressed the pollution aspect of nitrate runoff by designing a nitrate capture-system to prevent pollution in waterways. However, after discovering that increased CNF use can lead to decreased soil fertility, we made it another goal to recycle nitrate in addition to merely capturing it.

However, it seems that the only true, permanent solution to this issue is the stop of CNF usage altogether. For example, Professor Mulvaney talked to us about a method called liming, or the application of calcium and magnesium rich materials in the soil. This method is far less harmful than CNF and has the added benefit of softening the soil, increasing pores, and promoting the movement of water around plant roots. We hope that more attention will be brought to alternative methods of fertilization such as this, though we will still continue working on our current mitigation strategy of designing a nitrate-capturing construct.

Overall, gaining more insight into the harmful effects of CNF gave the team a better sense of our ultimate goal. Instead of just reducing nitrate pollution, we want to counteract the negative effects of the CNF industry, as well.