Sampling

The purpose of any soil sample is to obtain information about a particular soil. Information from the sample is of interest only insofar as it yields information about the population, and the information may or may not be representative, depending on how the sample is selected. The intensity with which a soil must be sampled to estimate with given accuracy some characteristic will depend on the magnitude of the variation within the soil population under consideration. The more heterogeneous the population, the more intense must be the sampling rate to attain a given accuracy. When a sample is actually drawn from the population, it is necessary to think of the population as composed of a number of separate units. The sampling plan designates which units of the population are to be included in the sample. In many types of soil investigation, the use of subsampling, or multistage sampling, is advantageous.