EXTENSION COURSE IN SOILS. 69 
during a season. This is because the additional quantity of water 
which the soil having the finer texture or the larger proportion of 
organic matter may hold is repeated after each succeeding rain, so 
that if showers come eight or ten times during a season and are fol- 
lowed by dry periods, the total quantity of water available to crops 
under the first-named condition is considerably larger than under 
the second. The capillary rise of water is comparatively fast in 
sandy soil, but it can not be raised from any great depth. The 
moisture of sandy soils which is retained by capillarity is more effec- 
tively used by the growing crop, however, than in the case of soils 
of finer texture. (Ref. No. 2, p. 161.) Besides, the portion of the 
ram falling as light or moderate showers after dry periods is more 
largely available to crops growing on sandy than on heavy soils. A 
rainfall of one-quarter inch will penetrate the sandy soils several 
inches and so reach the roots of the growing crop, while this amount 
of rain falling on a soil of fine texture will be absorbed and held so 
near the surface that it does not affect the roots of the plants, and 
practically all of it evaporates from the surface soon after the rain- 
fall. The control of soil moisture in sandy soils can be effected by 
the methods discussed under prevention of evaporation, page 28. 
Rolling these soils after seeds have been planted has the effect of 
increasing the movement of the water to the seed bed, but the field 
must be dragged after the rolling to prevent the evaporation of 
water from the surface. It is desirable to plant seed more deeply 
in sandy soils than in heavier or clay loam soil. Clover, or other 
small seed, should be sown an inch or an inch and one-half deep, 
so that it will have sufficient moisture for germination. 
The topography, or ''lay of the land," and the distance to the 
ground water of sandy soils is a matter of considerable importance. 
Owing to the freedom with which the water of the saturated portion 
of the subsoil can move in sandy soils, the ground water table is usu- 
ally quite level and does not rise as rapidly under hills of sandy soils 
as it does in hills of heavier soils. For this reason the upper portions 
of hills of sandy soils are usually so far above tbe ground water table 
that practically no water is drawn from the subsoil. On the other 
hand, when sandy soils are level or have only a very small slope, and 
the ground water table is 6 or 8 feet below the surface, a considerable 
amount of moisture may be drawn up far enough to reach the roots 
of growing crops. 
Wind blowing of sand. — In addition to danger from smothering by 
drifting soil, crops growing on sandy soils are often very seriously 
injured by the cutting action of sand blown against them. Not 
infrequently a single sand storm of a few hours' duration coming 
in spring or early summer will do as much damage as a severe frost. 
