Innovation Grant Spotlight: Getting the most from manure
Written by Jonathan Eisenthal
Manure provides a rich meal for your crops, but farmers are often left guessing the amount of nutrients included in each serving.
Trimont farmer A.J. Krusemark launched a three-year study through the Minnesota Corn Innovation Grant Program to get a better handle on the crop nutrition he was providing through injecting swine manure across several hundred acres that will grow corn the following year.
Krusemark’s hypothesis was he could maintain yield and stretch their manure resource by trying to hit a specific phosphorous rate, and then coming back and doing a small nitrogen side dress application to make up any shortfall. In order to consistently hit a phosphorous rate he needed a better way to test manure, on the spot.
“We’re trying to understand how much variability is there, from one tank load to the next, when you are drawing the manure from the same pit,” Krusemark said. “We take 40 and 50 samples from successive loads, to understand how stable the analysis is, from beginning to end.”
As an Innovation Grant participant, Krusemark was able to collaborate with Melissa Wilson, PhD, a manure nutrient management Extension specialist at University of Minnesota, on identifying a testing strategy.
Wilson worked with Krusemark to implement a procedure where an operator screens solids from the manure storage using a 1-millimeter mesh, and then relates the volume of the solids back to the total volume of the sample to get an estimate of the phosphorous contained in the sample.
To date, Krusemark has seen an excellent correlation between the rapid test and conventional lab tests from the same sample. He has reduced his application rate to between 2,500 and 2,750 gallons per acre—down from closer to 3,800 gallons. In the various tests, it appears that manure he once used to cover 190 acres can be used to cover 240 or even 300 acres, without a loss of yield.
“It comes back to what we want out of our operation, that we are really trying to do the best we can,” said Krusemark. “It’s an environmental stewardship conversation. It’s also a business profitability perspective.”
Krusemark undertook the project not just for himself, but because he feels a lot of farm operators are in his shoes.
“I wanted to help come up with a $5,000 or $10,000 dollar testing solution that gets you 90 percent of the way there,” Krusemark said. “Most hog producers today operate at a scale that they could pay for something like that within a year or two, with the savings from spreading manure out over additional land, at a lower rate.”
In addition to the savings and the reduced environmental impact, Wilson also touts the soil health benefits of Krusemark’s strategy.
“The other aspect is that manure has been shown for a lot of reasons to improve soil health, especially on fields that might not be as healthy as they could be,” Wilson said. “By applying manure at lower rates and using it across more acres, that can hopefully spread that soil health benefit farther.”
