. Productive soils; the fundamentals of successful soil management and profitable crop production. Soils. 96 SOIL WATER AND ITS RELATION TO SOIL FERTILITY Capillary Rise of Water in Soils,—This is the upward move- ment of water from the subsoil to the surface. This movement of soil moisture concerns capillary water only. A good illustration of this is the upward movement of water or oil in a lampwick. SufHce it to say that the force which causes this rise of water either in the soil or a lampwick is " capillarity.'^ When capillary water rises in soils it does not fill the pore spaces in b
. Productive soils; the fundamentals of successful soil management and profitable crop production. Soils. 96 SOIL WATER AND ITS RELATION TO SOIL FERTILITY Capillary Rise of Water in Soils,—This is the upward move- ment of water from the subsoil to the surface. This movement of soil moisture concerns capillary water only. A good illustration of this is the upward movement of water or oil in a lampwick. SufHce it to say that the force which causes this rise of water either in the soil or a lampwick is " capillarity.'^ When capillary water rises in soils it does not fill the pore spaces in between the soil particles, but rises or moves from soil grain to soil grain in films which surround the soil particles; thus capillary water may move not only upward, but in all directions, from a greater to a less amount of soil moisture. It is important that the pore spaces do not all become filled with water, because it is through these openings that air enters a soil; and air is one of the factors determining fertility. Factors Influencing Capillary Rise of Water. —There are several factors influencing the rise of water in soils, but we shall consider here only those which are of practical iiiiportance to the farmer; viz., soil texture, compactness or firm- ness of soil, and obstruction. Influence of Soil Texture.—Soil texture has a decided influence on the rise of soil moisture. In a fine textured soil water rises much higher but more slowly than in one of coarse texture (Figs. 40 and 41). Capillary water cannot rise upthroughgravel or coarse sand, thus a seed bed having a coarse sand subsoil is supplied with no appreciable amount of moisture from the subsoil through capil- larity. A seed bed of silt loam underlaid by silty clay, on the other hand, may be supplied with considerable capillary water from the subsoil to a depth of from four to five feet during a drought. King concluded that moisture may rise in silt loam soils from depths of ten feet in forty-five weeks
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