Plants are committed to a location. Wherever seeds fall, they place their roots in the soil and their branches in the air and live or die, thrive or subsist according to what they can do with what they get. The soil is the source of all of their supplies except sunshine and air. The available water is a function of soil type and weather. The soil, friendly provider, can also be an antagonist, clinging grudgingly to moisture needed by the plant. Soil types differ in their ability to retain water against gravity and release it to plants. Mineral content of soils also varies. Plants require some minerals in fairly large amounts and some in small amounts. The presence of those needed in only trace amounts is just as critical as those for which it is needed in large amounts.