200 HOW CROPS FEED. 
such to the eye, and free to obey the laws of gravity and 
motion. When the soil is saturated by rains, melting 
snows, or by overflow of streams, its pores contain hy- 
drostatic water, which sooner or later sinks away into the 
subsoil or escapes into drains, streams, or lower situations. 
Bottom Water is permanent hydrostatic water, reached 
nearly always in excavating deep soils. The surface of 
water in a well corresponds with, or is somewhat below, the 
upper limit of bottom water. It usually fluctuates in 
level, rising nearer the surface of the soil in wet seasons, 
and receding during drought. In general, agricultural 
plants are injured if their roots be immersed for any length 
of time in hydrostatic water; and soils in which bottom 
water is found at a little depth during the season of 
growth are unprofitable for culture. 
If this depth be but a few inches, we have a bog, 
swamp, or swale. If it is one and a half to three feet, 
and the surface soil be light, gravelly, or open, so as to 
admit of rapid evaporation, some plants, especially grasses, 
may flourish. If at a constant depth of four to eignt feet 
under a gravelly or light loamy soil, it is favorable to 
crops as an abundant source of water. 
Heavy clays, which retain hydrostatic water for a long 
time, being but little permeable, are for the same reasons 
unfavorable to most crops, unless artificial provision be 
made for removing the excess. 
Rice, as we have seen, (H. C. G., p. 252), is a plant 
which grows well with its roots situated in water. Hen- 
ric’s experiment with the raspberry (H. C. G., p. 254), 
and the frequent finding of roots of clover, turnips, etc., 
in cisterns or drain pipes, indicate that many or all 
agricultural plants may send down roots into the bottom 
water for the purpose of gathering a sufficient supply of 
this necessary liquid. 
Capillary Water is that which is held in the fine pores 
of the soil by the surface attraction of its particles, as oil 
