Elements of farm practice, prepared Elements of farm practice, prepared especially for teaching elementary agriculture; elementsoffarmpr01wils Year: 1915 Figure 3.—The ap- proximate composition plants. Some of the starch formed in a plant is slightly modified during the growth of the plant and forms fibrous tissue and sugar. Examine kernels of wheat and corn and a potato to see what a very large part is starch. The white part of them all is very largely starch. It is seen that by far the greater portion of our common plants does not come from the soil, as is usually supposed, but is formed fr
Elements of farm practice, prepared Elements of farm practice, prepared especially for teaching elementary agriculture; elementsoffarmpr01wils Year: 1915 Figure 3.—The ap- proximate composition plants. Some of the starch formed in a plant is slightly modified during the growth of the plant and forms fibrous tissue and sugar. Examine kernels of wheat and corn and a potato to see what a very large part is starch. The white part of them all is very largely starch. It is seen that by far the greater portion of our common plants does not come from the soil, as is usually supposed, but is formed from the poisonous gas, carbon dioxide, from the air, and water from the soil. Plant Food in the Soil.—A small por- tion of every plant comes from the plant food in the soil. A fairly good idea of the proportion of any plant that is taken from the soil is obtained by burning the plant. The ashes remaining represent nearly the ^Llii'part I'the^i^t'n whole amount that came from the sou. are composed of mm- ,^, . ,. ,, , n • i_ 1 i 1 erals taken from the soil. This portion, though small, is absolutely The rest is composed of necessary for plant growth. One may ^^^^J^ w°tn ^'''^ '^' liken the plant food taken from the soil to salt eaten by animals. It furnishes a very small part of the food required, but is absolutely necessary. Hence the impor- tance of having a fertile soil that will furnish these sub- stances as needed by the growing crop. Plants are able to get food from the soil only when it is in a soluble form—that is, when the plant food will dissolve in water as sugar dissolves in tea. Soluble Plant Food.—When a soil contains plenty of soluble plant food it is said to be fertile. When plant food becomes soluble in the soil it is dissolved in the soil water. This water containing the plant food, surrounds the fine roots and root hairs of the plant, and passes through their thin walls just as nourishment enters the blood vessels in the ani- mal body. In this way pla
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