In agriculture, a soil test is the analysis of a soil sample to determine nutrient and contaminated content, composition, and other characteristics such as the acidity or pH level. A soil test can determine fertility, or the expected growth potential of the soil which indicates nutrient deficiencies, potential toxicities from excessive fertility and inhibitions from the presence of nonessential trace minerals. The test is used to mimic the function of roots to assimilate minerals. The expected rate of growth is modelled by the Law of the Maximum. Soil testing is used to facilitate fertilizer composition and dosage selection for land employed in both agricultural and horticultural industries.