Untreated manure is high in phosphorus, so farmers face a difficult choice between applying too much phosphorus to a parcel of land or transporting manure farther away, which is time-consuming and expensive. Yahara WINS awarded a grant in 2020 to TRC, a consulting firm, to test methods for treating manure to reduce its phosphorus content.
In the project, manure from storage lagoons on a beef cattle farm was aerated to reduce their phosphorus content. In the aeration process, microbes consume phosphorus out of nutrient-rich wastewater and settle out, leaving less phosphorus in the liquid portion. There had been previous studies conducted in a lab to aerate the wastewater from the beef cattle farm, but the Yahara WINS grant funded this process at a larger scale to see if it would work in practice on a farm.
The study found that aeration of beef cattle manure reduces the phosphorus content of liquid manure by 90%. This means that if a cattle farmer were able to implement manure treatment on site, they could spread the same amount of manure on the same amount of land with a much lower phosphorus impact on that parcel of land.