If your manure storage is getting too full, Melissa Wilson offered some advice: try side-dressing.
Speaking at the North American Manure Expo recently, Wilson is an associate professor and Extension specialist focusing on manure nutrient management and water quality with University of Minnesota.
A lot of our manure storage was built in the 1970s. Since producers have expanded their operations to meet demand, “manure storage wasn’t enough,” Wilson continued.
To reduce the amount of manure in storage, colleague Glen Arnold with Ohio State University introduced her to side-dressing crops as a means of reducing the amount of stored manure on a livestock farm, especially for those with older, smaller storage areas.
She also said that side-dressing can help reduce days for manure application and manage nutrients better, as crops receive manure throughout the growing season.
Although it’s obvious that side-dressing will reduce the amount of manure in storage, Wilson’s research evaluated using side-dressing for manure management. Her on-farm study used a drag hose system – a small-plot study dragging a hose over corn at different growth stages – and a small-plot study using a tanker with different application equipment.
The dragline system was for a corn-corn-soybean rotation using 40 lbs. of nitrogen in starter. The side-dress was 140 lbs. of nitrogen at stage V4 or V5. Wilson compared swine manure with the dragline at less than 3,500 gallons/acre with anhydrous ammonia, liquid UAN at 32% and no nitrogen side-dressing applied.
In 2018, the yield was nearly identical on all parts of the test plot – around 200 bushels/acre, except for in the control, where operators applied no side-dressing (141 bushels/acre). In 2019, the yields varied, with 228 for the anhydrous ammonia, 171 for the dragline, 208 for UAN and 89 for the control. One explanation Wilson suggested for the difference between the two years’ yield was the operator applied only 90 lbs. of nitrogen in the second year instead of 140 as in 2018.
“If we’d had the right amount on, we’d probably have similar yields,” Wilson said.
Manure spreader demonstrations were part of the North American Manure Expo in Auburn, NY, on July 18. Photo by Deborah J. Sergeant
The timing of side-dressing application matters.
“Dragging at V1 through 3 was safe and didn’t affect the corn at all compared with not dragging,” Wilson said. “As long as the growing point is underneath, you’ll be fine.”
The researchers even dragged the lines up and back in a “worst-case scenario” and found it did not unduly damage the crop.
But at V4 and later, dragging did reduce yield for hybrid P0339R. For hybrid P0306AM, dragging at V5 and V6 reduced yield.
In a separate trial of a soybean-corn rotation, Wilson used 40 lbs. of nitrogen in starter fertilizer and side-dressed dairy manure and swine manure. The farmer used sweep injection with 7,000 gallons applied; manure disk-injected; 17,000 gallons/acre of manure surface broadcast; urea with urease inhibitor; and a no-nitrogen control area. She averaged her findings over two years.
Not surprisingly, the control yielded the lowest amount at 122 bushels/acre. The nitrogen-only area yielded 162 bushels. Surface manure, disk-injected manure and sweep-injected manure at VE were close at 169, 161 and 155, respectively.
For areas side-dressed at V6, yields were 165 for fertilizer, 172 for surface manure, 162 for disk-injected and 158 for sweep-injected manure.
“We did have a lot of variability,” Wilson said. “With sweeps, we were probably hitting roots. Maybe use not such a broad sweep. We did like sweep a little bit better.”
Overall, her research indicates that side-dressing liquid manure into corn is beneficial.
“Swine manure is a good nitrogen source for side-dressing and so is dairy when the right equipment is used,” Wilson said. “You can safely inject manure with a dragline system up to V3, maybe V4. Disk injection might be better than sweep injection, depending on your sweeps.”
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