Frequently, in evaluating plant deficiencies, one considers only those soil factors which are associated with the fertility of the soil-- mainly the levels of phosphorus, potash, nitrogen, and organic matter. A certain level of nutrition is essential for plant growth, but in order for the nutrients to exert their maximum influence on the productivity of the soil, it is equally important that a good soil environment be provided and maintained. A good environment requires that good physical conditions of soil, sir, and water be in balance.