. Productive soils; the fundamentals of successful soil management and profitable crop production. Soils. SOURCES OF ELEMENTS PLANTS REQUIRE 35 r0er grew. About 290 years ago it was thought that a plant was nothing more than water that had undergone a naysterious change in the soil. Only within compara- ^^ tively recent years ^^^^ has it been found that the chemical composition of plants is quite simi- lar to that of soils. The elements required fey plants and without which they cannot grow are ten in number; viz., nitrogen, phos- phorus, potassium, calcium, mag- nesium, sulfur, iron, carbon,
. Productive soils; the fundamentals of successful soil management and profitable crop production. Soils. SOURCES OF ELEMENTS PLANTS REQUIRE 35 r0er grew. About 290 years ago it was thought that a plant was nothing more than water that had undergone a naysterious change in the soil. Only within compara- ^^ tively recent years ^^^^ has it been found that the chemical composition of plants is quite simi- lar to that of soils. The elements required fey plants and without which they cannot grow are ten in number; viz., nitrogen, phos- phorus, potassium, calcium, mag- nesium, sulfur, iron, carbon, oxygen and hydrogen. All the mineral elements are to be found in ashes. Silicon, sodium, aluminum and other elements are found in ash but they are not neces- sarily essential to plant growth, since plants can grow without them. Ash, then, is the mineral portion of plants. Sources of Ele- ments Plants Re- quire.—Plants secure the elements they require from the following sources: 1. The soil—^fmrnishing nitrogen and mineral elements. 2. The soil water—^furnishing oxygen and hydrogen. 3. The air—furnishing carbon and Fig. 15 —The root system of a potato plant in a per- meable soil. This also illustrates the sources of the elements required by plants (After Rotmistrov). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Weir, Wilbert Walter, 1882-. Philadelphia London, J. B. Lippincott company
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectsoils, bookyear1920
