692 
Journal of Agricultural Research voi. xxvu, No. 9 
Where the subsoil of an irrigated field is saturated with water or con¬ 
tains strata or barriers that are slowly permeable to water, effective 
leaching of the soil is seriously hindered because of the accumulation of 
underground water. 
The lateral movement of underground water, like the downward 
movement of water through the soil, is subject to great variation, depend - 
ing upon local conditions, and the quality and concentration of the 
solution are also highly variable even within the same field. 
The comparison of the quality and concentration of underground 
waters from different parts of the field with those of the irrigation water 
permits a better understanding of the drainage requirements of the soil 
than is possible from observing only the depth to the underground 
water. 
The injurious effects that have been ascribed to sodium carbonate or 
“black alkali” in irrigated soils appear to be due to the sodium rather 
than to the carbonate, and sodium in solution even when associated with 
the stronger acids combines with the soil and ultimately causes defloccu¬ 
lation and impermeability. 
The readjustment of the relative proportions of sodium and other bases 
in an impermeable soil, to the end of improving the physical condition, 
depends upon replacing the sodium with another base, such as calcium 
or aluminum, which, when combined with the soil brings about a floccu¬ 
lated and permeable condition. 
LITERATURE CITED 
(1) BreazealE, James F. 
1923. NUTRITION OF PLANTS CONSIDERED AS AN ELECTRICAL PHENOMENON. In 
Jour. Agr. Research, v. 24, p. 41-54, 5 fig. 
(2) Briggs, Lyman J., and McLane, J. W. 
1911. MOISTURE EQUIVALENT DETERMINATIONS AND THEIR APPLICATION. In 
Proc. Amer. Soc. Agron., v. 2 (1910), p. 138-147, pi. 6. 
(3) -and Shantz, H. L. 
1913. THE WATER REQUIREMENT OF plants. U. S. Dept. Agr. Bur. Plant 
Indus. Bui. 284, 49 p., 11 pi. Literature cited, p. 49. 
(4) Burd, John S., and Martin, J. C. 
1923. WATER DISPLACEMENT OF SOILS AND THE SOIL SOLUTION. In Soil Sci., 
v. 13, p. 265-295, i fig. References, p. 295. 
(5) Burgess, Paul S. 
1922. THE SOIL SOLUTION, EXTRACTED BY LIPMAN’S DIRECT-PRESSURE METHOD, 
compared with i : 5 water Extracts. In Soil Sci., v. 14, p. 191-212, 
2 pi. References, p. 212. 
(6) Cummins, Arthur B., and Kelley, Walter P. 
1923. THE FORMATION OF SODIUM CARBONATE IN SOILS. Univ. Calif. Pub. 
Tech. Paper 3, 35 p., 2 fig. References, p. 31-35. 
(7) Elliott, W. R., Murphy, D. W., and Code, W. H. 
1919. DRAINAGE REPORT [MADE To] SALT RIVER VALLEY WATER USERS’ ASSOCIA¬ 
TION, 1919. 15 p. Phoenix, Ariz. 
(8) Gedroiz, K. K. (Gu^droitz, K. K.) 
1914. DIE KOLLOID-CHEMIE IN FRAGEN’ DER BODENKUNDE. In Zhur. Opit. 
Agron. (Russ. Jour. Exp. Landw.), v. 15, p. 181-216. [In Russian. 
German resum6, p. 205-216.] 
1916. POUVIOR ABSORBANT DU SOL ET LES BASES Z^OLITIQUKS DES SOLS. In 
Zhur. Opit. Agron. (Jour. Agr. Exp.), v. 17, p. 472-528. [In Russian. 
French resume, p. 527-528.] [English translation by S. A. Waksman, 
42 p., 1923. Mimeographed.] 
(10) Jensen, Charles A. 
1918. RELATION OF INORGANIC SOIL COLLOIDS TO PLOWSOLE IN CITRUS GROVES 
in southern California. In Jour. Agr. Research, v. 15, p. 505-519. 
Literature cited, p. 518-519. 
