However, if some areas of manure differ in appearance, take samples in proportion to the size and number of these areas. For example, if ten percent of the manure differs from the bulk of the pile, then take ten percent of the total sample from those areas. Otherwise, sample randomly throughout the entire storage area. Ideally, stored litter has an impervious surface beneath it and a cover over it. Uncovered waste develops a weathered exterior that may not accurately represent the majority of the material.
Rainfall moves water-soluble nutrients through the pile.
If the litter is unprotected and used over an extended period, take new samples before each application. Always sample to a depth of at least 18 inches at six or more locations. Surface-scraped and piled materials are similar to stockpiled litter. They need protection from the weather. Follow the same procedures for taking samples.