U tests sewage-based fertilizer

by Emily Dalnodar

Every time a toilet in Milwaukee flushes, the University’s lawns get a little greener.
An organic fertilizer made from sewage water is getting its first trial at the University this spring and summer. Produced in Milwaukee, Milorganite takes a stab at solving one of Wisconsin’s water pollution problems. Additionally it provides a good source of plant nitrogen.
Milorganite, a name combining the words Milwaukee, organic and nitrogen, consists of nothing more than filtered sewage. Through a lengthy process, waste water’s solid material separates from the liquid. The water then contains only microscopic organic matter. When exposed to oxygen, microorganisms break down the matter at the cellular level.
Removing the oxygen kills the microorganisms. The solids settle, the water is removed, and the remaining biomass becomes the base of the fertilizer. The process not only purifies water but utilizes materials that once would have gone into landfills. Now it sits atop University foliage.
“It’s pure Milwaukee crap,” said Jim Blake, University grounds crew superintendent. “And 3 percent of whatever is in the bag is pure nitrogen, and the rest is organic matter, which helps release nitrogen.”
Other fertilizer mixes with Milorganite before University grounds crew members apply it to lawns and gardens. Although the organic alternative can work alone, the addition of conventional fertilizers reduces costs and the number of necessary applications.
Increasing nitrogen levels without using damaging salts is one of Milorganite’s advantages. Most fertilizers slowly release nitrogen with salt. Salt burns foliage, turning it brown.
Although made from raw sewage, Milorganite safely fertilizes lawns, said Carl Rosen, University soil, water and climate professor. The filtration process kills off any potential disease-causing pathogens using heat.
While Milorganite meets all of the Environmental Protection Agency requirements, Rosen warns against using it on vegetable gardens. Because production of Milorganite takes place in an industrial area, many heavier metals can mix into the fertilizer and create a hazard to food safety, he said.
But because Milorganite is organic, it decreases the chance of ground water contamination, said Patrick Weicherding, University horticulture professor. The brand breaks down nitrogen, using living organisms, releasing it as needed. Most commercial fertilizers use water soluble nitrogen so every time it rains, more is released.
Besides Milorganite, grounds crews are testing a few other methods during the summer to compare results. It is too early to determine the product’s effectiveness. But everything is lush and green right now, Blake said.