SSMG-41 (D.E. Clay, C.G. Carlson, and J. Chang)

Determining the “Best” Approach to Identify Nutrient Management Zones: A South Dakota Example

Summary:

Productivity zones, yield stability maps, and management zone maps based on elevation, electrical conductivity, yields, and remote sensing may be developed using a variety of different approaches. Producers frequently ask: Which method for identifying zone boundaries is best? The answer to this question depends on the criteria used to evaluate the zone boundaries. At least three different criteria for assessing management zone boundaries are used. These criteria are:
• The ability to group areas with similar soil test results into the same zone;
• The ability to group areas with similar yields into the same zone; and
• The ability to improve fertilizer recommendations.
For the two South Dakota fields used in this study, if the goal was to group areas with similar yields into the same zone, then zones based on personalized soil surveys were best. However, if the goal was to minimize nitrogen (N) and phosphorus (P) recommendation errors, then this was accomplished by using multiple years of yield monitor data to develop landscape specific yield goals, sampling old homesteads separately from the rest of the field, and grid-cell soil sampling to fine-tune N and P recommendations. Similar analysis can be conducted in your field if you have multiple years of yield data and an understanding of soil nutrient variability.





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