Although soils are composed largely of oxygen, silicon, and aluminum, plants growing in soil by no means reflect this composition. Carbon and oxygen, followed by hydrogen, make up the bulk of the dry weight of plants. These elements are obtained from carbon dioxide and water. More than 50 elements have been found in various plants, compared to the total of 92 known natural elements. Plants are able to absorb in their roots many of the existing elements available in solute form from the surrounding solution. Plants do have the partial ability to select the rate at which they absorb various ions, so that absorption is usually not in direct proportion to their concentration in the growth media. The species vary in their ability to select particular ions.
KeywordsToxicity Hydrated Cobalt Brittle Chlorine
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