Productive farming . lable to plants,except for the securing of nitrogen from air, when inoculationwith certain bacteria may be necessary. The foods ta,kenfrom the soil on the other hand are much less available, andthe ability of plants to seciu-e them may depend very largelyon the efforts of the farmer. It is necessary for the farmerfirst of all to study his soil to see how he can make its plant-food most available. What Soil is.—That part of the earths surface whichcan be tilled, and in which plants grow, is called soil. It isthe loose, highly decomposed layer of mineral matter result- HOW S
Productive farming . lable to plants,except for the securing of nitrogen from air, when inoculationwith certain bacteria may be necessary. The foods ta,kenfrom the soil on the other hand are much less available, andthe ability of plants to seciu-e them may depend very largelyon the efforts of the farmer. It is necessary for the farmerfirst of all to study his soil to see how he can make its plant-food most available. What Soil is.—That part of the earths surface whichcan be tilled, and in which plants grow, is called soil. It isthe loose, highly decomposed layer of mineral matter result- HOW SOILS ARE FORMED 43 ing, primarily, from rock decay, which furnishes food andfoothold for plant and animal life. Soli Builders.—Soil is derived from two main classesof substances; rock and organic matter. Rocks crumbleinto fine particles. They are gradually being changed intosoil. Plants and animals decay to form the organic matteror humus in the soil. The humus present in our fields ischiefly of vegetable Fig. 24.—-\ high bank of wind-blomi soih Notice where it has nearly covered thefence. (Plant Industry.) How Soils are Formed.—Certain forces are constantlyat work changing rock into soil and making soil particlesfiner. These forces are: (1) air; (2) water; (3) temperature;(4) plants; (5) burrowing animals; and (6) minute plantand animal organisms. These forces act both physically andchemically. Exercise.—Soil Forming.—Find places near the schoolor at home where any of the agencies mentioned are at workforming soil. Tell of the places and what you have you find places where water has carried soil? How arethe little gulleys formed in hillsides? Where is the soilcarried to? u PRODUCTIVE FARMING The Action of Air and Temperature Changes.—The action of the air and the changes in temperature, which together wecall weathering, is of many kinds. The heat of the sun causesthe rock to expand. As all of the substances which make upa rock do not expand the
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu, booksubjectagriculture
