OMAHA (DTN) -- Nutrients recovered from animal and human waste could reduce synthetic fertilizer use in the U.S., according to a new Cornell University study.

Cornell researchers found animal and human waste in the U.S. could theoretically meet 102% of nitrogen and 50% of phosphorus needs for the nation's agriculture -- a value of more than $5.7 billion annually. A major challenge in using this waste is the frequent mismatch between the location of the waste and agricultural regions with the highest fertilizer needs.

The waste can be used locally and more than half of the surplus nutrients can be redistributed to nearby regions with low economic and environmental costs. The research team found large percentages of recoverable nutrients in the waste -- 37% of nitrogen and 46% of phosphorus.

"This is a coordination problem, not a resource problem," Chuan Liao, corresponding author and assistant professor in the Cornell CALS Ashley School in the College of Agriculture and Life Sciences, said in a press release. "Even considering the real-world constraints, there's still a substantial amount of nutrients that can be economically redistributed to meet crop needs."

The research provides a blueprint for harnessing the untapped potential of animal and human waste to reduce the United States' reliance on synthetic fertilizer. These fertilizers are often energy-intensive to produce, harmful to the environment and often made overseas.

Liao said excessive use of these fertilizers can lead to water pollution. In addition, supply chain issues can lead to great food insecurity, as the Iran war is showing.

Researchers mapped potential sources of human and animal waste as well as the need for nutrients across 15 major crops, at a resolution of around 10 kilometers (6.21 miles).

Nutrient surpluses occurred in population-dense areas and livestock-intensive regions, such as the Northeast and parts of the West, while deficits persisted in the Midwest and southern Great Plains. Researchers then analyzed the potential for redistributing nutrients, given the cost of both processing and transportation.

The team found that areas of very high or very low nutrient supply often overlapped with poorer counties, where people are more vulnerable to food insecurity and worse overall health. Liao said pollution could be a factor.

In surplus regions, more waste washes into the bodies of water and in areas of low-nutrient supply, farmers rely more on synthetic fertilizer, which can degrade soils and pollute water as well.

"The nutrient inequality seems to mirror social inequality in a large sense," he said. "So potentially fixing the nutrient flow can promote environmental justice."

Liao said the best approach to scale the use of waste in U.S. agriculture is to take advantage of opportunities at the local level. He gave the example of a hog farm in the middle of miles of corn fields. With the right infrastructure and incentives, waste from the hog farm could be used to satisfy the nutrient-hungry corn fields right next door.

"We're advocating for a decentralized system, so that waste can be processed locally," Liao said. "But in order to do this, we need to coordinate across different sectors such as agriculture, waste and energy. The technology is there, but we need governance and infrastructure to scale the entire U.S."

The study is part of a larger research program at Cornell exploring the feasibility of using human and animal waste as fertilizer globally. Funding for the study came from the National Science Foundation and USDA, with seed funding from the Cornell Atkinson Center for Sustainability.

Russ Quinn can be reached at Russ.Quinn@dtn.com

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