Oct. 30,1916 Spongospora subterranea and Phoma tuberosa 
237 
slope sufficient for the rapid drainage of surface waters. On the tract were 
found certain fairly well marked differences of color, texture, and other 
physical characteristics of the soil. These soils, which are here desig¬ 
nated by a set of arbitrary numbers, are as follows: 1 
Soil, 1.0.—The surface is grayish brown to ashy gray, depending on the 
moisture content. The texture is silty loam, fairly friable when dry, but 
somewhat plastic when wet. Numerous small stones and gravel occur 
in the soil and subsoil, the latter being a light ashy-gray or mottled gray 
and brown and rather heavy silty loam. The drainage of this soil is suf¬ 
ficient for surface run-off, but appears to be deficient in the subsoil, 
probably due to seepage of water from the higher lying upland. This 
type comprises the greater area of the tract. 
Son, 1.1.—The surface of this soil is light brown and is underlain by a 
subsoil which is gray and much like that of No. 1.0. The texture is 
about the same as that of the foregoing type, though the structure of the 
surface is more open and friable, stone and gravel are not so conspicuous 
a feature, the surface is more sloping, and the subsoil drainage is freer. 
Son, 1.2.—The color of the surface is slightly darker than that of No. 
1.0, though the subsoil is about the same and the texture is a silty loam. 
In the area in the northeastern corner of the tract the content of small 
stone and gravel is extremely high, so that the amount of interstitial soil 
material is considerably reduced. The two small areas on the southeast¬ 
ern corner of the tract are less stony, the percentage being about the same 
as in soil 1.0. The texture of the subsoil is rather finer than that of the 
surface and more compact, the color being a dark grayish brown or gray 
slightly mottled with brown to the depth of 3 feet or more. The soil 
occupies relative depressions along natural drainage ways, and in the 
larger area there is considerable erosion. While the surface drainage 
seems adequate, there is so much seepage apparently that the internal 
drainage is actually poorer than in soil 1.0. 
Soil, 2.0.—This soil is a medium- to light-brown silty loam and con¬ 
tains considerable gravel of a smaller size generally than is common to the 
other types. The subsoil is reddish brown to yellowish brown, with a 
somewhat larger amount of small gravel than in the surface. There is no 
mottling, oxidation being quite uniform in both soil and subsoil. This 
type differs from all other soils in that there is no gray mottling in the sub¬ 
soil. The topography is abrupt or rolling and both surface drainage and 
subdrainage are free. 
Figure 1 2 shows the distribution of the soil types on the portion of the 
field used. 
1 The description of soils here given was very courteously contributed by Mr. J. E, Dapham, Scientist in 
Soil Survey, Bureau of Soils. 
2 This map was made by Dr. Oswald Schreiner and Messrs. J. E. Eapham and H. L. Westover, of the 
Bureau of Soils, through whose kindness it is published. It was of great value in interpreting results of the 
experiments. 
