We take pride in high resolution maps so 10 zones are required. This allows enough flexibility to vary rates of product across fields with significant variability. We know some fields with minimal variability may require less than 10 different rates of a product. In those cases, the same rate may be applied to multiple zones. On rare occasions, for small fields with minimal variability, the zone map may contain less than 10 zones.
It is important to understand that properties of one variable may not vary significantly through some zones, but another property will. A high resolution map is needed to capture the variability that does exist, and we've found 10 zones is a good balance between resolution and practicality.
