. Western agriculture. deficient in organic matter. This fault may be rem-edied by addition ofbarnyard manure orby plowing under ofplant residues orgreen manure. Thesoil texture may bemodified by thor-ough, continued cul-tivation, such as iscarried on in theproduction of themulch in dry-farmingoperations. Baking of soils, on ac-count of a deficiencyin organic matterand limestone, havea tendency to bake,,become hard andcompact. Althoughour arid soils are notrich in organic mat-ter, they are exceptionally rich in limestone and, as a result,baking of soils is not common with them.
. Western agriculture. deficient in organic matter. This fault may be rem-edied by addition ofbarnyard manure orby plowing under ofplant residues orgreen manure. Thesoil texture may bemodified by thor-ough, continued cul-tivation, such as iscarried on in theproduction of themulch in dry-farmingoperations. Baking of soils, on ac-count of a deficiencyin organic matterand limestone, havea tendency to bake,,become hard andcompact. Althoughour arid soils are notrich in organic mat-ter, they are exceptionally rich in limestone and, as a result,baking of soils is not common with them. Black alkali soilshave a tendency to bake, but this may be readily overcomeby the addition of gypsum. If the baking of a soil is causedby the absence of humus, provision should be made for theaddition of barnyard manure or for the plowing under ofgreen manure, such as a crop of alfalfa, clover, or and Subsoil. In a humid section the native plantroots penetrate into the soil to a uniform depth of twenty to. Figure 29.—Soil and subsoil. SOIL TEXTURE AND STRUCTURE 93 twenty-four inches, and, when they decay, there is a char-acteristic change in color below this point. The under partis called subsoil. The surface soil is dark colored, while thesubsoil is light in color. No such change in color is noticed in soils of the aridregion, because ournative plant rootspenetrate to muchgreater penetration ofthe plant roots ismade necessary bytheir search formoisture and possi-ble by the almostuniform textureand structure of thearid soils to consid-erable depth, as in-dicated in the abovetable. This uni- Figure 30.—Root system of alsikc clover plant, show- IOrmlty rendersing immense growth of roots which are so beneficial VI 1 in enrichment of soil by the clover crop. pOSSlDle deeper plowing in the aridregion than in a humid section where the turning up of thesubsoil renders the soil nonproductive. Influence of Moisture Content. The moisture contentof the soil is
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
