Below are examples of soil fertility maps of High Desert fields created with grid sampling.
NOTE: Maps A and B show a 90.8 acre onion field. Map C shows a 234.4 acre alfalfa field. Map D shows a 58.1 acre onion field.
Map A: Phosphorus
Map B: Potassium
Map C: Phosphorus
Map D: Potassium
Agriculture and Natural Resources, University of California