30 
Journal of Agricultural Research 
Vol. IX, No. a 
the plants by the roots being developed into these depths, but little water 
being elevated by capillarity from the zone below that traversed by the 
roots (2, p. I2l). 
Metal cylinders from 2 to 6 feet long and 4 inches in diameter were 
filled with a subsoil having a hygroscopic coefficient of 5.6, half with soil 
in a moister condition and half with it in a drier, allowed to stand for 
several months and then the change in moisture distribution determined. 
In most of the experiments the moisture content of the drier soil was 
approximately equal to the hygroscopic coefficient. When the water 
content of the moister soil was below about twice the hygroscopic coeffi¬ 
cient, the capillary movement of water in any direction was slight; but 
when it was distinctly above this, there was a practically uniform move¬ 
ment from the moister into the drier soil (3, p. 286). 
The work of Rotmistrov (23), near Odessa, covers a period of 15 years, 
1895-1909. The ground water there lies at a depth of over a hundred 
feet and the soil is a Chernozem containing 3 to 5 per cent of organic 
matter. He assumes the “useless” (nonavailable) water at all depths 
in this soil to be about 10 per cent and attaches physiological importance 
to only the portion in excess of this. Moisture determinations, some 
60,000 in all, were made at frequent intervals throughout the year at 
successive intervals of 5 or 10 cm., in some cases to a depth of 7 feet or 
more, both in clean fallows and under a great variety of crops. He found 
that when the subsoil is moist, the roots of annual crops penetrate to 
a depth of 2 to 5 feet and those of various perennials—alfalfa, trees, and 
shrubs—sometimes as deep as 60 feet. On the old plowed fields he found 
a permanently moist layer of subsoil extending from 4^ or 5% feet to the 
water table, while on waste land occupied by weeds, etc., the permanently 
moist layer was encountered first at 14 to 30 feet. Above this is, first, 
a layer of subsoil which becomes moist or dry according to whether it is 
in fallow or crop, and, lastly, overlying the latter is the surface layer, 
varying from less than 2 to as much as 5 feet, which in every year becomes 
moist. He concludes that water percolating beyond a depth of 16 to 20 
inches does not return to the surface except by way of the roots, the 
portion escaping the roots going down into the deeper layers at the rate 
of about 7 feet yearly. 
Using glass tubes and wooden boxes, he carried out experiments with 
soil from the experimental field. Placing these in water, he observed a 
rise of less than 3 feet in three months. As the movement is so slow in 
the soil with water less than 3 feet below the surface, he concludes it will 
not move at all in the field where it is at a depth of over 100 feet. 
Burr (9), from a 7-year study (1907 to 1913) of the total moisture in 
the first 3 to 15 feet of the comparatively uniform loessial soil on the 
table-land at North Platte, Nebr., where the water table is at a depth of 
over 200 feet, concludes that there is little upward movement of subsoil 
water, and that— 
