Papers on Horticultural and Kindred Subjects (1891) p. 37-38
By William Saunders
Superintendent of Gardens and Grounds, U. S. Department of Agriculture.

(Originally published 1883)

The statement is sometimes made that draining is of but little use in a climate where hot dry suns and dry weather are so common; that instead of trying to get rid of the water we should rather try to retain it; but those who reason in this way do not seem to be aware that the purpose served by draining land is the removal of superfluous water only, and not that of extracting all the available moisture which it contains. Every variety of soil has its relative degree of porosity or power of retaining moisture. Peaty or mossy soils, which are mainly composed of organic matter in different stages of decomposition, are very porous, and in consequence absorb water readily and in great quantities. Clay soils, on the other hand, being close and compact, absorb water slowly and to a limited degree as compared with the first mentioned. Draining a peaty soil will not deprive it of porosity. It may be likened to a sponge, which will retain all the water which may be poured on it until its pores become filled; afterwards the water will drop from it as fast as it is poured on. So it is with draining soil; no water will escape by the drains until the soil is saturated and is unable to contain any more; then the superfluous water passes off by the drains, leaving the land always in a condition for healthy plant growth, which is completely reversed when the superfluous water is only removed by the slow and chilling process of surface evaporation.

Clay soils can not be cropped to their best advantage until they are drained. The ordinary operation of plowing has a tendency to form a hard surface at the bottom of the furrow, which in time becomes compacted and acts as a basin holding water. Soils of this kind are well designated as cold. The heat of the sun can not warm the soil until the water is first removed by evaporation, a process which produces cold; so that, in addition to the impracticability of putting in crops early in spring, every heavy summer rain cools the earth, and the plants growing in it receive a series of checks in their progress towards maturity. Draining removes all these evil consequences.

Briefly, it may be stated that some of the advantages of draining are the removal of superfluous water from the soil, thus keeping the temperature of the earth near the surface at its normal state. This makes early planting possible, and hastens the growth of the crops; it equalizes the temperature of the land; it equalizes the moisture of the soil, and growing plants are thus, to a great degree, exempted from the evils which follow either deficiency or excess of rainfall; the roots of plants are more generously supplied with soluble food carried down by rains; the formation of plant food is increased by admission of air to the soil; the land is more economically worked, and cultivation suffers less interruption at all seasons, and, as a consequence, crops are increased to their maximum production, at least so far as they are dependent upon the physical condition of the soil, a factor of equal importance with that of its chemical constitution, and one which is greatly underestimated.