. Soil physics and management. is, Wisconsin and Indiana have consid-erable areas of sand dunes. A large part of these areas is coveredwith a scrubby growth of black oak and other trees, which furnishcomplete protection. When this giowth is removed, however, itis very difiicidt to hold the sand and it is the part of wisdom toleave even the poor gro\\d;h of forest for purposes of dune areas covered with prairie grasses peculiar to the sandpresent different problems. As a general rule, there is sufficientorganic matter in the surface six to eight inches to^ hold the sandparticles.
. Soil physics and management. is, Wisconsin and Indiana have consid-erable areas of sand dunes. A large part of these areas is coveredwith a scrubby growth of black oak and other trees, which furnishcomplete protection. When this giowth is removed, however, itis very difiicidt to hold the sand and it is the part of wisdom toleave even the poor gro\\d;h of forest for purposes of dune areas covered with prairie grasses peculiar to the sandpresent different problems. As a general rule, there is sufficientorganic matter in the surface six to eight inches to^ hold the sandparticles. When the soil is cropped or pastured, some of this sur-face soil may be removed by the wind in exposed places, forming EOLIAL OR WIND-LAID DEPOSITS 59 what is called a blowout (Fig. 56). The tendency is for thisto increase in size and often results in ruining large areas. Toreclaim these blowouts it is necessary to grow legumes, plantsable to take their nitrogen from the air. The black locust (Fig. 57) 0^k^ =? •if**-^^^ a. Fig. 56.—Large blowout in sand area. Numerous small ones may be seen in the dis-tance. Mason County, Illinois
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherphila, bookyear1917
