What is the principle of soil sampling?

Soil testing is a significant part of soil resource management. Each sample collected act as representative of the area being sampled. Utility of the results obtained from the laboratory analysis depends on the sampling precision. In order to obtain sample of desired size by sub-sampling collection of large number of samples is advisable. Sampling is done at the rate of one sample for every two hectare area in general. For a maximum area of five hectares at-least one sample should be collected . Samples are collected from a soil profile representative to the soil of the surrounding area for soil survey work .