Fighting Feces with Fire: Research Shows How to Transform Manure into Dry Fertilizer

Managing cow manure has historically been a hassle for farmers, but new research shows how it can be transformed into valuable dry fertilizer. 

By using a process called pyrolysis, which “burns” organic matter at temperatures of 700 to 1,200 degrees F without oxygen, researchers from Cornell and Bio365 found that the nutrients from manure can be retained and forged into an environmentally sound biochar fertilizer. 

In New York State, the prominent dairy industry’s cows produce not only milk, but also a lot of manure. According to the authors, New York dairy herds produce12.8 million metric tons of manure annually. This manure is typically stored in lagoons or spread onto fields, which can create nutrient management, disposal, and environmental headaches.

If all that nutrient-rich manure was pryloized instead, farmers could capture the equivalent of 11,732 to 42,232 metric tons of nitrogen. This has a value of $6 to $21.5 million and could satisfy 23% to 82% of the state’s nitrogen fertilizer needs. It would have the added benefit of reducing environmental pollution and decreasing the greenhouse gas emissions associated with commercial fertilizer production. 

Pyrolization works well with manure due to its water content, according to Johannes Lehman, Professor in Soil and Crop Science at Cornell. 

“You’re reducing the volume of the solid waste product that has 90% water and reducing it to zero water,” Lehman told the Cornell Chronicle. “[The dry fertilizer] is safe because the solids are pyrolyzed. There are no pathogens, no hormones or antibiotics residues or any other material that could contaminate soil or water.” 

The end product is a dry, solid fertilizer that can be sold, stored, and marketed and the problem of disposing of large pools of liquid manure is no longer an issue. 

Crops also benefit from this biochar fertilizer. Leilah Krounbi, a doctoral student at Cornell and lead author of the new research, successfully grew tomatoes and radishes in the biochar. She also found ways to increase the nitrogen content of the biochar by treating it with carbon dioxide, which led to greater crop growth and nitrogen uptake. 

Fire changed the course of human history and now is poised to revolutionize how manure is managed. 

Read more about using pyrolysis to convert manure into fertilizer at Cornell Chronicle.