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Compost Sampling and Mailing Procedure

The sample you collect for analysis must be representative of the entire material being analyzed. Piles of compost or feedstock often vary from place to place in the pile or windrow.

Therefore, the sample sent for analysis should be a composite sample of material collected from several locations and depths within the windrow or pile being sampled. The number of sampling points will depend on the size and configuration of the pile or windrow. In most situations, material should be collected from at least 5 locations around the pile or windrow and from three depths at each location. Separate composite samples should be collected from different windrows or piles.

To collect a composite sample:

  1. You will need a clean auger, soil probe, or spade, a clean 5 gal plastic bucket, a clean plastic tarp, and a 1-2 quart sample container (heavy plastic zip-loc bag, or wide mouth plastic bottle).
  2. Proceed to the first sampling location and collect approximately 1 pint of material from near the surface of the windrow, another pint of material midway to the core of the windrow, and another pint of material from near the core of the windrow. Place the samples in a clean 5 gal plastic bucket.
  3. Repeat this process at each of the sampling locations in the windrow or pile, adding the samples to the 5 gal bucket.
  4. When you have completed sample collection at all sampling locations, thoroughly mix the material in the bucket being careful to avoid stratification of the different particle sizes. Depending on the consistency and volume of the sampled material, mixing can be facilitated by dumping the material on a plastic tarp and mixing thoroughly to ensure homogeneity prior to taking a composite sample for analysis.
  5. Collect your composite sample from the mixed material. The volume of the composite sample needs to be 1 to 2 quarts depending on the tests you are requesting. Place the material in a suitable clean container for shipping. Label the container to identify the sample. Complete the compost sample analysis submission form. Mail the form, the labeled sample, and a check or money order for the appropriate amount payable to The Pennsylvania State University. To pay by credit card, complete the credit card authorization form listed below the compost submission form. Samples should be mailed directly to the laboratory as rapidly as possible.