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Unformatted text preview: Plant Nutrients and Soil - 1 As studied in Biology 211, cells need a variety of atoms and molecules to sustain life. Animals extract their nutrients, including organic fuel molecules, from the foods they consume by the process of digestion. Absorbed nutrients are circulated to cells and tissues, and non-digested materials are eliminated as waste products. Because animals obtain the vast majority of their nutrients from the foods they eat, obtaining food resources is a major activity of most animals. (See ecology section) . Most of us are familiar with the nutrient requirements for humans, and we know that if we fail to make good nutritional choices we may have health problems and nutritional deficiencies. Plants, too, have nutrient requirements. Although plants manufacture their own carbohydrates, proteins and lipids from inorganic materials, they require a number of minerals and other molecules needed to synthesize their cells' needs. If plants do not get their needed nutrients, they will have growth problems just like we do. The ways in which plants obtain their nutrients is quite different from methods used by animals to obtain food. Plants focus on obtaining inorganic materials from their local environment rather than searching for appropriate food choices, not surprising since plants are fixed in location. Plants are autotrophs. They obtain raw materials from their environment. Plants need about 18 elements, mostly mineral ions, along with oxygen, water, and carbon dioxide. Plants process these nutrients into their needed organic and inorganic molecules for plant structure and function. Plants produce few waste products because they have no need to extract nutrients from pre-formed organic materials (like we do), and their fuel needed to do cell work is provided by photosynthesis In this section we will look at what nutrients are needed by plants and how they get them from their environment. We may also touch on environmental change as it impacts plants and ways some plants have to augment their mineral uptake. Plant mineral requirements In addition to carbon, hydrogen, and oxygen, which comprise about 98% of the fresh weight of the plant, several other chemical elements, called the essential inorganic nutrients, are needed for plant growth. Nine of these, including nitrogen, potassium, calcium, phosphorus, magnesium, and sulfur (along with carbon, hydrogen, and oxygen), are required in relatively large amounts and are known as macronutrients. The remaining essential inorganic nutrients: iron, chlorine, copper, manganese, zinc, nickel, molybdenum, and boron, are required in very small, or trace amounts (as little as a few parts per million), and are known as micronutrients. The micronutrients function primarily as cofactors. A chart of plant mineral nutrients and their functions follows (Oxygen, carbon and hydrogen are often not included in plant mineral requirement lists) : Plant Nutrients and Soils - 2 Plant Nutrients and their Functions Plant Nutrients and Soils - 3...
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- Spring '09