By Andi Anderson
Manure is a valuable resource for farming, rich in nitrogen, phosphorus, and potassium. But the nutrient content of manure changes depending on how it’s stored and mixed. This makes it hard for farmers to know exactly how much their crops are receiving.
Traditionally, farmers collect manure samples and send them to labs for analysis. While helpful, this method can be slow, costly, and not fully accurate since nutrient levels vary as manure is emptied from storage.
To solve this, researchers tested a new technology: a real-time manure sensor. The John Deere HarvestLab 3000, currently the only system of its kind, uses near-infrared spectroscopy (NIRS) to measure nutrients instantly during application.
Mounted on a manure tanker with a flow meter and rate controller, the system adjusts the speed of the tractor or flow rate to apply the correct amount of nitrogen.
This method was tested in Wisconsin on silty soil. Researchers compared it to the traditional method using fixed rates and lab results. The sensor hit nitrogen targets more accurately—within 20 to 30 pounds of the goal—while the traditional method was off by 40 to 95 pounds per acre.
The sensor also tracked phosphorus and ammonium, though it needs improvements for those nutrients. Still, the precise nitrogen control helped avoid overuse and saved on fertilizer costs. Corn yields and nitrogen efficiency were similar across both methods, but the sensor used less nitrogen to achieve the same results.
Another benefit was how the sensor detected nutrient changes when manure wasn’t mixed well, showing its value in real-time adjustment.
Researchers plan to test the tool further and improve phosphorus readings. This innovation could help protect water, reduce waste, and support better soil health, proving that smart manure use is key to strong, sustainable farming.
Categories: Michigan, Sustainable Agriculture