Water and Plant Growth

Over vast areas of the United States, the growing of vegetables, for example, is practically impossible without some means of supplying water artificially. Elsewhere, the incorporation of large amounts of organic matter improves the water holding capacity of soils to tide plants over periods when water is scarce.

Water is particularly important when mineral or chemical fertilizers are used. Since they are usually salts, they are hygroscopic and will actually pull water out of plant tissues unless they are in dilute solutions. Either they should be applied before soil is dug or tilled, or should be applied with a hose ready to water them in thoroughly as soon as applied.

Water in excess can cause problems. What is not commonly known is that roots are incapable of absorbing water and nutrients unless oxygen is also present in soil. A plant top can actually wilt for lack of water while its roots are completely submerged. The ideal soil is one that can absorb abundant water in its organic substances, but one in which the passages between the organic and mineral particles are filled with air.

On heavy soils, which are easy to overwater, the common recommendation of allowing plants to dry out between watering has some validity, but on most soils fit for growing plants, a much sounder policy is to keep the soil constantly moist to the root depth, without applying so much water that air passages are drowned out.