Soil Report Volume 10 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 Excerpt: ...As the type approaches the brown silt loam, the organic matter amounts to as much as 3.8 percent, while as it approaches the yellow silt loam, it diminishes to as low as 2.3 percent. In some cases it is extremely difficult to draw the line between the long-cultivated brown silt loam and the yellow-gray silt loam, because of the gradation between the types. The subsurface stratum varies from 3 to 10 inches in thickness, erosion having reduced its thickness on the more rolling areas. It is usually a gray, grayish yellow, or yellow silt loam, somewhat pulverulent, but becoming more coherent and plastic with depth. The amount of organic matter is about 1 percent, or 20 tons per acre in the four million pounds of soil. The subsoil is a yellow or mottled grayish yellow, clayey silt or silty clay, somewhat plastic when wet, but friable when only moist, and pervious to water. Glacial drift is sometimes encountered at a depth of less than 40 inches. This is due to the removal by erosion of part of the loessial material. The glacial drift may be locally a very gravelly deposit, but usually it is a slightly gravelly clay and in some places is lacking in permeability. Otherwise, each stratum of this type is quite pervious to water, except in the level gray areas, where the tight and more or less compact clayey layer has been formed at a depth of 18 to 24 inches. Small areas of light gray silt loam on tight clay are found in the county, but none large enough to be shown on the map. In the management of this type one of the most essential things is the maintaining or the increasing of organic matter. This is necessary in order to supply nitrogen and liberate mineral plant food, to give better tilth, to prevent "running together," and on some of the more rolling...