Objectives Know the definition of element, compound, macronutrient and micronutrient. Know the 16 essential nutrient elements. Learn how to use the "Key to Nutrient Disorders ".
Important Definitions An element is a pure chemical that contains only one type of atom. A compound is a molecule that contains one or more elements. “Mineral”: An inorganic element Acquired mostly in the form of inorganic ions from the soil “Nutrient”: A substance needed to survive or necessary for the synthesis of organic compounds
Essential Elements The 16 elements required by plants are obtained from the soil, water and air. Thirteen of these elements must be supplied by the soil. Six of the soil elements required by plants are needed in relatively large amounts and are usually added to the soil through fertilizer or lime. These are called macronutrients. The remaining 7 elements supplied by soil are required in very small amounts and are termed micronutrients.
Macronutrients Element Symbol Source Macronutrients are needed in Oxygen O Air/Water relatively large Hydrogen H Air/Water amounts by Carbon C Air/Water plants. Nitrogen N Soil Phosphorus P Soil Sulfur S Soil Potassium K Soil Calcium Ca Soil Magnesium Mg Soil
Macronutrients – Form Used By PlantsNutrient Form UsedCarbon CO2 Charge on theOxygen H2O moleculeHydrogen H2ONitrogen NO3-, NH4+Phosphorus H2PO4 & HPO42-Potassium K+Calcium Ca2+Magnesium Mg2+Sulfur SO4-
Micronutrients Macronutrients are Element Symbol Source needed in Iron Fe Soil relatively small Manganese Mn Soil amounts by plants. Boron B Soil They are usually Molybdenum Mo Soil supplied by fertilizers. Copper Cu Soil Zinc Zn Soil Chlorine Cl Soil
Micronutrients – Form Used ByPlantsNutrient Form Used Charge on theIron Fe2+ moleculeManganese Mn2+Boron H2B03-Molybdenum MoO42-Copper Cu2+Zinc Zn2+Chlorine Cl-
Nutrient Deficiency Symptoms Nutrient deficiency symptoms usually appear on the plant when one or more nutrients are in short supply. In many cases, deficiency may occur because an added nutrient is not in the form the plant can use. Deficiency symptoms for specific elements are included on the "Key to Nutrient Disorders".
Nutrient Deficiencies Every soil is not susceptible to the same nutrient deficiencies. For example, coarse-textured soils low in organic matter are susceptible to sulfur deficiencies whereas sulfur is usually in adequate supply in clayey soils or soils high in organic matter.
Macronutrient Deficiencies & SoilsElement Soil Factor Causing DeficiencyN&K Excessive leaching on coarse-textured low organic matter soilsP Acid low organic matter soils Cold wet soils such as occurs during early spring Newly cleared soilsS Excessive leaching on coarse-textured low organic matter soils in areas where air pollution is low (minimal levels of SO2 in the air)Ca & Mg Excessive leaching on coarse-textured low organic matter soils Soils where large amounts of K have been applied
Micronutrient Deficiencies & SoilsElement Soil Factor Causing DeficiencyFe Poorly drained soils, Low organic matter soils, pH>7.0, Soils high in PZn Cold wet soils low in organic matter and highly leached, High pH soils (pH>7.0), Soils high in P, Exposed subsoilsCu Peat and muck soils, High pH, sandy soils, Soils heavily fertilized with NB Excessive leaching on coarse-textured low organic matter soils, Soils with pH>7.0Mn Excessive leaching on coarse-textured low organic matter soils, Soil with pH>6.5Mo Soils high in Fe oxides, high adsorption of molybdenum, Soil cropped for a long time
Deficiency Symptoms - N General chlorosis. Chlorosis progresses from light green to yellow. Entire plant becomes yellow under prolonged stress. Growth is immediately restricted and plants soon become spindly and drop older leaves.
Deficiency Symptoms - P Leaves appear dull, dark green, blue green, or red-purple, especially on the underside, and especially at the midrib and vein. Petioles may also exhibit purpling. Re- striction in growth may be noticed.
Deficiency Symptoms - K Leaf margins tanned, scorched, or have necrotic spots (may be small black spots which later coalesce). Margins become brown and cup downward. Growth is restricted and die back may occur. Mild symptoms appear first on recently matured leaves.
Deficiency Symptoms - Ca Growing points usually damaged or dead (die back). Margins of leaves developing from the growing point are first to turn brown.
Deficiency Symptoms - Mg Marginal chlorosis or chlorotic blotches which later merge. Leaves show yellow chlorotic interveinal tissue on some species, reddish purple progressing to necrosis on others. Younger leaves affected with continued stress. Chlorotic areas may become necrotic, brittle, and curl upward. Symptoms usually occur late in the growing season.
Deficiency Symptoms - S Leaves uniformly light green, followed by yellowing and poor spindly growth. Uniform chlorosis does not occur
Deficiency Symptoms - Cu Leaves wilt, become chlorotic, then necrotic. Wilting and necrosis are not dominant symptoms.
Deficiency Symptoms - Fe Distinct yellow or white areas appear between veins, and veins eventually become chlorotic. Symptoms are rare on mature leaves.
Deficiency Symptoms - Mn Chlorosis is less marked near veins. Some mottling occurs in interveinal areas. Chlorotic areas eventually become brown, transparent, or necrotic. Symptoms may appear later on older leaves.
Deficiency Symptoms - Zn Leaves may be abnormally small and necrotic. Internodes are shortened.
Deficiency Symptoms - B Young, expanding leaves may be necrotic or distorted followed by death of growing points. Internodes may be short, especially at shoot terminals. Stems may be rough, cracked, or split along the vascular bundles.
Crops Highly Susceptible to DeficienciesElement CropsMn Soybean, Small Grain & PeanutsCu Wheat & CornZn CornMo Soybeans & CauliflowerB Alfalfa, Apples, Peanuts, Tobacco & TomatoesFe Ornamentals, Fruit Trees, Soybeans, Grain Sorghum & Some Grasses