Applying both manure and commercial fertilizer on cropland is allowed—but only if the combined application rates do not exceed the nitrogen (or phosphorus) needs of the crop—as calculated in your current manure management plan. Confinement site owners are required to submit MMPs and keep a current MMP at the site or within 30 miles of the confinement. You must include all commercial fertilizer as part of your nitrogen (or phosphorus) application.
If applying manure on cropland which they don’t own or rent, confinement site owners need a statement that specifies the planned rate of commercial fertilizer (N and P) for each field that will receive manure. DNR’s Statement of Intent (form 542-8167) is available to help collect this information from the landowners, renters or tenants.
There are times, such as during a wet spring, when you suspect there may be a nitrogen deficiency. If soil test or crop nitrogen test results show a deficit, then additional nitrogen fertilizer may be applied as necessary to obtain the optimum crop yield. In other words, if you can prove a crop is nitrogen deficient, then you can apply additional nitrogen up to the calculated crop nitrogen need.