Precision Ag technology has long been available to manage fertilizer. More recently, new technology is allowing no-tillers to better manage manure nutrients.

To learn how to use precision technology more efficiently, Dr. Dick Wolkowski, University of Wisconsin Extension soil scientist, and I have conducted research on two Wisconsin farms sponsored by the University of Wisconsin, the National Pork Producers, John Deere and Mapshots.

Manure Variability

We found that as farms become larger and manure is stored in lagoons, the manure quality changes during application, even though we continually agitate manure. Figure 1 shows how phosphorus changes as we empty the lagoon.

To overcome nutrient variability, we recommend producers sample manure every 4 to 8 hours during application and link this sample information to where manure was applied. To do this, we time-date the samples and use site verification with an in-tractor monitor when applying the manure.

We also link a flow meter to the in-tractor monitor to get the manure flow rate. Steering systems were also used to keep manure applications uniform, improve field efficiency and reduce operator fatigue.

With these pieces of information, we use precision agriculture software to link the tractor location, manure rate and manure-sample information together to develop map layers for each nutrient. This shows how much of each nutrient was applied from the manure in all areas of the field.

Prescription Nutrients

After we know the level of each nutrient applied, we can produce a prescription map to apply the remaining needed nutrients with variable-rate…