. Annual report of the Agricultural Experiment Station. Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). 480 Agricultural Experiment Station, Ithaca, N. Y. Hoic the soil holds its water. That a proper understanding of the question may be reached, it is necessary to have a knowledge of the conditions under which water exists in the soil, and of the part it plays in the mysterious operations of plant growth. Water may be in one of three forms, —as free, capillary, or hygroscopic water. The free water of the soil is that which flows under the influence of grav
. Annual report of the Agricultural Experiment Station. Cornell University. Agricultural Experiment Station; Agriculture -- New York (State). 480 Agricultural Experiment Station, Ithaca, N. Y. Hoic the soil holds its water. That a proper understanding of the question may be reached, it is necessary to have a knowledge of the conditions under which water exists in the soil, and of the part it plays in the mysterious operations of plant growth. Water may be in one of three forms, —as free, capillary, or hygroscopic water. The free water of the soil is that which flows under the influence of gravity. It is the source of supply for wells and springs. It is not directly used by plants and its presence in the soil within eighteen inches of the surface is detrimental to the growth of most cultivated crops. It is valuable, however, because it is the supply from which capillary water is drawn. The capillary water does not flow by gravity. It is the direct source of moisture for plants. It may be either drawn upwards or it may pass downwards depending upon whether the soil is drier at the surface or below. In time of droughts, the capillary action of the soil may be sufiicient to raise the water through a distance of five or six feet, its power in this respect depending directly upon its physical condition. If the soil is coarse and cloddy and the particles are not compact, then the w^ater can not rise to take the place of that which is carried off by evaporation or used up by plants in their growth. If, however, the soil is fine, in good condition, and homogeneous, the water passes ,,^ .,^ ., , ^ freely and continuouslv to the surface. No- 139.—The soil mulch. '^ tice the track of the horse on the plowed ground, or the foot-print of the driver, and see how the moisture comes directly to the surface, because the soil has been com- pacted and there is intimate capillary relation between its parti- cles. This moist surface shows that the water is passing off from it into th
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