Information provided by the soil and tissue tests at this level is used to optimize N management practices one farm at a time. This includes all the activities in level three, but many corn producers work cooperatively to get more extensive evaluations of management practices in less time. A pilot program demonstrating this level of management has been initiated as the N-Check Program in west central Iowa. This is a cooperative effort of the Raccoon River Watershed Project, the Iowa Corn Promotion Board, the Iowa Farm Bureau, the Leopold Center for Sustainable Agriculture, and the USDA Sustainable Agriculture Research and Education Program. As part of the N-Check Program, producers collect samples and record relevant information about soil types, management practices, and location of the test area.
Producers get results for their farm and a summary analysis of all data collected.
The large number of samples helps identify trends that one producer would not be able to identify. The trends enable comparison of factors such as time or method of application. They also show how these factors interact with soil types and weather. Producers can compare their results to the average of many other farms using similar or dissimilar management practices. This gives an objective basis for selecting among the many alternative fertilization practices currently available to producers.