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Chap 13. Plant Nutrition 1. Plant Nutrients Macronutrients Micronutrients 2. Chemical Fertilizers Commercial Analysis Elemental Analysis 3. Fertilizer Concentration Calculations ppm mM Meq/liter 4. Fertilizer Application Preplant Application Top Dressing Liquid Feeding 1. Essential Nutrietns of Plants Element Chemical symbol Atomic weight Ionic forms Absorbed by plants Approximate dry ____ concentration_____ N 14.01 NO3-, NH4+ P K Mg S Ca 30.98 39.10 24.32 32.07 40.08 PO43-, HPO42-, H2PO4K+ Mg2+ SO42Ca2+ Fe Mn Zn Cu B Mo Cl 55.85 54.94 65.38 63.54 10.82 95.95 35.46 Fe2+, Fe3+ Mn2+ Zn2+ Cu2+ BO32-, B4O72MoO42Cl- Mccronutrients Nitrogen % Phosphorus Potassium Magnesium Sulfur Calcium 4.0 0.5 % 4.0 % 0.5 % 0.5 % 1.0 % Micronutrients Iron Manganese Zinc Copper Boron Molybdenum Chlorine 200 ppm 200 ppm 30 ppm 10 ppm 60 ppm 2 ppm 3000 ppm Essential But Not Applied Carbon C 12.01 CO2 40 % Hydrogen H 1.01 H2O 6% Oxygen O 16.00 O2, H2O 40 % ________________________________________________________________ Plant tissues also contain other elements (Na, Se, Co, Si, Rb, Sr, F, I) which are not needed for the normal growth and development. 2. Macronutrients a. Nitrogen (N) 1) Soil Nitrogen Cycle a. Nitrogen (N) 1) Soil Nitrogen Cycle a) Nitrogen Fixation -Transformation of atmospheric N to nitrogen forms available to plants - Mediated by N-fixing bacteria: Rhizobium (symbiotic) found in legumes (bean, soybean) Azotobacter (non-symbiotic bacteria) b) Soil Nitrification - Decomposition of organic matter into ammonium and nitrate - Mediated by ammonifying and nitrifying bacteria Ammonifying bacteria (Actinomycetes) Plant residue (Protein, aa, etc) → Nitrifying bacteria (Nitrosomonas) NH4+ Ammonium → NO2 Nitrite (Nitrobacter) → NO3Nitrate Nitrogen (N) Deficiency Symptoms Yellowing of mature lower leaves- nitrogen is highly mobile in plants Macronutrient Deficiencies Beans Macronutrients N, P, K Deficiencies Leaf Lettuce Control Phosphorus (P) Availability Leaf Margin Necrosis in n Poinsettia Potassium (K) Deficiency Blossom End Rot of Tomato Calcium Deficiency Right-Hydroponic tomatoes grown in the greenhouse, Left-Blossom end rot of tomato fruits induced by calcium (Ca++) deficiency Influence of Calcium on Root Induction on Rose Cuttings Magnesium (Mg) Deficiency on Poinsettia Interveinal Chlorosis on Mature Leaves Micronutrients • Micronutrient elements – – – – – – – Iron (Fe) Manganese (Mn) Boron (B) Zinc (Zn) Molybdenum (Mo) Zinc (Zn) Copper (Cu) Chloride (Cl) • Usually supplied by irrigation water and soil • Deficiency and toxicity occur at pH extremes Influence of pH on Nutrient Availability Iron (Fe) Deficiency Symptoms 1 2 3 4 A 1-Piggyback Plant, 2- Petunia, 3-Silver Maple, 4-Rose (A-normal, B-Fe-deficient) B Iron Chelates Iron (Fe) Absorption by Plants Micronutrient Toxicity on Seed Geranium B Cu Fe Mn Mo Zn Cont 0.25 0.5 1 2 3 Concentration (mM) 4 5 6 Molybdenum Deficiency on Poinsettia Fertilizer Analysis Fertilizer Concentrations • Fertilizer Analysis – Commercial Analysis – Elemental Analysis • Fertilizer Concentrations – Parts per million (ppm) – Mili-molar (mM) – Mili-equivalent per liter (meq/L) Fertilizer Application Plant growth in influenced by a nutrient of lowest concentration as a denominator Amounts of Fertilizer Applied Fertilizer Application Fertilizer Application Liquid Feeding of Greenhouse Crops Use of Soluble Fertilizers Peter’s 20-20-20 Soluble Fertilizer Lack of Soluble Fertilizer in Mexico Lowers the Quality of Crops Grown in Greenhouse Fertilizer Injector A Two-head Injector (Proportioner) Used for Greenhouse Crops Purification of Water by Filtration (RO Water) The Ebb-and-Flow System The Floor Irrigation Seystem (Subirrigation) Crops Grown with Sub-Irrigation System