. Western agriculture. eep soil. plant food, but this fact does not relieve the farmer of thenecessity of getting his soil into proper physical conditionwhich greatly influences the temperature of the soil, thefood supply, the penetration of the plant roots, and thecirculation of soil air necessary to the bacterial life of thesoil. This physical condition is structure; it has nothing todo with the size of the particles. How to Modify Soil Structures. The rock particles inthe soil are still subject to the same weathering influencesby which they were formed and are by them being continu-ally cha
. Western agriculture. eep soil. plant food, but this fact does not relieve the farmer of thenecessity of getting his soil into proper physical conditionwhich greatly influences the temperature of the soil, thefood supply, the penetration of the plant roots, and thecirculation of soil air necessary to the bacterial life of thesoil. This physical condition is structure; it has nothing todo with the size of the particles. How to Modify Soil Structures. The rock particles inthe soil are still subject to the same weathering influencesby which they were formed and are by them being continu-ally changed in texture to a slight extent. The farmer haslittle control over the texture of the soil. Sandy soilremains sandy; clay soil remains clay. Much, however, may SOIL TEXTURE AND STRUCTURE 91 be done to modify the structure so as to increase its crop-producing power. The structure may be modified by plow-ing or cultivating at the proper time. If the soil is plowedor cultivated when too wet, the heavier clay soil has a. Figure 28.—This picture was taken a few days after a heavy rain, previous to whichthere nad been thorough cultivation. Note the baking and cracks resultingfrom a lack of proper physical condition. tendency to puddle, or break into a hard impervious massunsuited for crop production. Fall plowing gives the weathering agencies, such as frostand water, a better chance to penetrate the soil and thusrender possible the preparation of a good seed bed. Thepresence of water-soluble salts also materially modifies thestructure of the soil. Thus it is somewhat common in thearid West to have very coarse-textured soil, similar to sand,consisting mostly of limestone particles cemented togetherby the water-soluble salts. Some of the alkali salts, such assodium carbonate, or black alkali, cause the soil particles torun together, forming a hard, impervious mass which can bestbe destroyed by the addition of gypsum. 92 WESTERN AGRICULTURE An acid soil may be improved by the addit
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
