Summary: T0day we talk about the essential major and trace elements that plants need and why (at least when we know WHY!). (http://www.bpc.edu/mathscience/chemistry/images/periodic_table_of_elements.jpg) *The essential plant processes of Absorption, Carbon assimilation, Formation of protoplasm and Transpiration. *During growth the lant uses water and oxygen to change carbon and nitrogen into things it can use. *During growth the plant produces many things such as sugars, starch, cellulose, acids, lignin, tannins, amino acids, proteins, amides etc., and many plants also produce toxins such as alkaloids, nicotine, etc. *The plant has to take in enough water to keep these activities going. Water is so very important in the uptake of nutrients! Minerals and the roles they play. Major elements (high use): Nitrogen, phosphorus, calcium, magnesium, potassium, sulfur. Trace elements (low use but still high importance): Iron, manganese, boron, copper, zinc and molybdenum. Sodium, chlorine and silicon are beneficial but not essential. Aluminum occurs in plants but doesn’t really serve a role. It does exert indirect influences on nutritional processes such as using aluminum sulfate. The nutrient elements can only be absorbed by plants when present in certain forms: nitrogen from nitrates and ammonium salts; phosphorus from phosphates; calcium, magnesium and potassium from their salts (e.g., as sulfates or chlorides, etc.); sulfur from sulfates; iron from ferrous or ferric salts more readily from ferrous salts); manganese from manganous salts; boron from borates; copper and zinc from their salts, and molybdenum from molybdates. There may appear to be certain exceptions. For instance, nitrogen may be applied to a soil as "organic" nitrogen, as in hoof meal or urea, and sulfur may be added as the element itself, as in flowers of sulfur, ground sulfur, etc. In such conditions the added materials are, however, converted into the nitrate and sulfate forms respectively by soil organisms before being absorbed by the plants. Further points of importance in connection with the absorption of the mineral nutrients by plants are as follows: * The minerals have to be diluted. * Certain of the elements slow down the absorption of others into the plant. * Healthy plants result when the nutrients are absorbed in certain relative proportions. * Nutrients, even though present in the nutrient solution in satisfactory amounts and proportions, may not be absorbed by the plant unless the "reaction" of the solution as regards acidity and alkalinity is satisfactory. Functions of ESSENTIAL MAJOR ELEMENTS Nitrogen. Nitrogen is the major plant element. Nitrogen compounds comprise from 40 to 50% of the dry matter of the living substance of plant cells. Phosphorus: This element, like nitrogen, is closely concerned with the vital growth processes in plants. Phosphorus is also of special importance in the processes concerned in root development and the ripening of seeds and fruits. Calcium: One of its main functions is as a constituent of the cell wall. Magnesium: A constituent of chlorophyll, and is essential to the formation of this pigment. Like iron in human blood/Hemoglobin Potassium: Not clearly understood. Sulfur: It seems to be connected with chlorophyll formation. ESSENTIAL TRACE ELEMENTS Iron: Iron is closely concerned with chlorophyll formation but is not a constituent of it. Its role appears in this connection to be that of a catalyst. Manganese: The functions of manganese are regarded as being closely associated with those of iron. Zinc and Copper: About the same as iron. mangold and barley. Sodium seems to affect the water relations of plants and often enables sugar beet and other crops to withstand drought conditions which would otherwise produce severe adverse effects. SIGNS OF FAULTY NUTRITION IN PLANTS * Changing color of leaves - yellowing
