How many soil samples do you take from each field?

All SWAT MAPS have 10 zones, and suggested standard practice is to sample 5 of those 10 zones. This however can depend on the extent of variability, the size of the field, and cost of lab fees. It is up to the SWAT Certified Agronomist to work with the farm and determine the best course of action that captures the full extent of landscape variability. Because there is a smooth gradient of soil properties from SWAT zone 1 to 10, it is rarely necessary to sample all 10 zones. Instead we can interpolate the results to each zone based on lab results and knowledge of the field.
It can vary upon the size of the field, but a larger field (>160 ac/60 ha) will typically have 5 geo-referenced points per zone, using 2-3 cores per point, or 10-15 cores per zone to make up each sample that goes to the lab.