8. Sub-sampling and Composite Sampling

Subsampling. In many soil investigations, subsampling or multi-stage sampling is advantageous. To subsample, first divide a sample unit into small portions. Then choose a second sample from these portions and measure it according to the characteristics under consideration. This method of sampling, frequently used when bulk density cores are taken, saves both time and money.

Composite sampling. When conducting laboratory analysis, using a composite sample instead of individual samples saves time and money. To obtain composite samples, first take a number of field samples of equal amount sufficient to represent the population. Then mix them to form one composite. Laboratory analyses is done on this composite or a subsample of it.