Using grid soil sampling to guide manure application can be a profitable investment, is the conclusion from case studies based on eight Minnesota farms. In fields where there is a history of non-uniform manure application, targeting new manure applications to areas with lower phosphorus and potassium soil test values can result in considerable economic returns above the cost of grid soil sampling. Variable rate manure applicators are not required when fields can be divided into application and no-application zones, with supplemental nitrogen fertilizer in the no-manure zones. The brief case studies are available on the University of Minnesota Extension web page for Manure Management and Air Quality http://www.manure.umn.edu, under Grid Soil Sampling for Manure Application. An introduction, the eight case studies, and a set of short video presentations based on the case studies are available at http://z.umn.edu/gridsoilsampling.
Funding for the development of these case studies was provided by the McKnight Foundation.