Nutrients

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Nutrients

• Chapter 7

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Essential Nutrients

• Nonmineral
• Carbon
• Oxygen
• Hydrogen
• Mineral

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Essential Nutrients

• Macronutrients
• Nitrogen
• Phosphorus
• Potassium
• Micronutrients
• Boron
• Copper
• Zinc
• Iron
• Manganese
• Molybdenum
• Chlorine

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Fertilizers

• Added to the soil, plant, or other growing medium
  to supply the nutrients
• Mixture of nitrogen, phosphorus, and potassium

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Nitrogen

• Most abundant and mobile nutrients
• Part of chlorophyll which gives plants their
  green color.
• Very mobile and subject to many physical,
  chemical, and biological processes
• Deficiency cause yellowing in plant

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Nitrogen losses

• Nitrification- decomposed organic material or
  inorganic fertilizers to a nitrate form
• Leaching-
• Fine-textured soils lose less than 5
• Greatest loss occurs with sandy soils
• Erosion-greatly reduced by using approved soil
  conservation practices

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Nitrogen losses

• Denitrification-saturated with water causes
  anaerobic condition
• Gas is released into the atmosphere
• Volatilization-increase in temperature causes
  nitrogen to be broken down and released as a gas

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Nitrogen Cycle

• Removal of nitrogen from the atmosphere
• Nitrogen fixation
• Legumes
• Commercial fertilizers
• Organic Matter (Humus)
• CN ratio (page 147)
• 251 ration ties up nitrogen
• 121 ration most desirable

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Phosphorus

• Immobile in soil, removed with soil particles
• Adequate supply near plants roots system early
  in growth
• Maximum availability occurs under slightly acid
  soil conditions
• Deficiency causes blue-green to purple leaves
• Sources include Diammonium phosphate and triple
  superphosphate

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Potassium

• Second most used by plants
• Deficiencies symptoms include scorching or
  browning along leaf margins
• Source is potash

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Secondary Micronutrients

• Sulfur
• Essential in amino acids, vitamin gives green
  color
• Yellow upper leaves stunted growth
• Calcium
• Constituent of cell walls aids cell division
• Deformed or dead terminal leave pale green color
• Magnesium
• Component of chlorophyll, enzymes, and vitamins
  aids nutrient uptake
• Interveinal yellowing of lower leaves

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Micronutrients

• Most apt to limit crop growth
• Highly leached acid sandy soil
• Muck soils
• Soils high in pH or lime content
• Soil that have been intensively cropped
• Soil heavily fertilized with macronutrients

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Micronutrients

• Iron
• Catalyst in chlorophyll formation component of
  enzymes
• Intervienal chlorosis of upper leaves
• Copper
• Chlorophyll synthesis and respiration
• Terminal buds and leaves die blue- green color
• Manganese
• Chlorophyll synthesis
• Dark green leaf veins interveinal chlorosis

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Micronutrients

• Zinc
• Need for auxin and starch formation
• Intervienal chlorosis of upper leaves
• Molybdenum
• Aids nitrogen fixation and protein synthesis
• Similar to nitrogen
• Boron
• Important to flowering, fruiting, and cell
  division
• Terminal buds die thick, brittle upper leaves
  with curling

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Nutrients unavailable for plants

• Insoluble chemical compounds
• Unweathered or undecomposed minerals
• Organic matter or plant residues

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Interactions that reduce absorption

• Ammonium-potassium
• Potassium-magnesium
• Phosphorus-nitrogen
• Phosphorus-zinc

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Soil pH

• Page 154
• Causes of acid soils
• Removal of calcium, magnesium, and potassium
• Increase of nitrates
• Adjusting soil pH
• Applying lime and sulfur

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Lime

• Contains calcium and magnesium
• Functions
• Sweetens the soil
• Improves the availability of plant nutrients
• Increases the effectiveness of N,P, and K
• Increases the activity of microorganisms
• Improves plant growth and crop yields

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Foliar Symptoms

• Deficiencies among plants
• Includes
• Nutrient deficiencies
• Insect, disease, nematode , drought, and
  pesticide damage

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Tissue Testing

• Rapid tissue testing
• Uses green tissue or the extract for green tissue
• Dry tissue testing
• Uses dried leaves
• Done on split sample by different labs
• More time-consuming and more expensive

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Fertilizer sources

• Liquid or Solid
• Foliar Fertilization
• Animal Manures

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Fertilizer Placement

• Provide adequate quantities
• Irregular distribution
• Early stimulation of the seedling
• Soil characteristics
• Dry soil
• Salt levels
• Placement of fertilizer

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Animal manure

• 16 ton of manure/ 1 ton of livestock/year
• 500 lbs of absorbent litter/ 600 lbs of liquid
• Addition of supersphosphate to prevent loss of
  ammonia

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