PO 16. Recognize how the following affect soil sampling methods.

Within-field soil and crop variability encompasses other uncontrollable differences within a field.  Thus, there are a minimum recommended number of sub-samples to be taken, and recommendations on the areas those samples should be taken from.

• Take 2-3 sub-samples per acre and then combine.  One composite sample should not represent more than 10 acres, unless past sampling shows minimal differences.
• The area to be sampled should be fairly uniform: similar soil properties and past management.
• If there are known significant differences within the area (such as old fence rows, manure or lime stockpile areas, wet spots, etc), then a modified sampling strategy should be followed.
• If the areas are too small to manage separately, avoid taking any sub-samples from these areas.
• If the areas are large enough for the farmer to practically manage them separately, take separate samples from these areas.