FINAL EXAM

• Nutrient deficiency symptom


  Used to evaluate nutrients lacking in the soil by observing the growing crop
• Nitrogen deficiency


  This deficiency results in yellow or light green color in leaves
• Phosphorus deficiency


  Older leaves dull purple and necrotic spots and redish part at the tip of leaf margin
• Potassium deficiency


  Older leaves severe marginal Scorch and forward curling of leaf margins
• Bronzing


  due to spotting and scorching of leaves(potato)
• Marginal necrosis


  tip burn
• Sulfur deficiency


  The veins and petioles show a very distinct reddish color
• Magnesium deficiency


  Leaves yellow between veins
• Calcium Deficiency


  Death of growing point and die-back of main stem from tip
• Defloration


  removal or lose of flower
• Iron Deficiency


  show strong chlorosis at the base of the leaves with some green netting
• Boron deficiency symptoms.


  - Terminal (end)/buds growing point may die

  - light general chlorosis
• Copper Deficiency


  Leaves are curled, and their petioles bend downward
• Zinc Deficiency


  interveinal necrosis but the main veins remain green
• Chlorine Deficiency


  leaves have abnormal shapes, with distinct interveinal chlorosis
• Molybdenum Deficiency


  mottled spotting
• Manganese Deficiency


  light interveinal chlorosis
• Cobalt Deficiency


  reduced Vitamin B12 production and lower nitrogen fixation (Hidden sign)
• Soil Test Kit


  Rapid method of assessing the fertilizer needs of plants/Basis of fertilizer recommendations
• Microbiological Method


  Used to approximate the degree of deficiency of element through the growth of test organism
• Azotobacter plaque method


  used to evaluate P, K and Ca by putting all elements in a medium except the desired element for testing.
• Aspergillus Niger Method


  black spores are being produced and weigh the pad (mycelia) to evaluate K, Mg, Zn, and Cu relating amount of nutrient in standard soil
• Soluble salts such as MgSO4, MgCl2, CaSO4, or CaCO3 may be present in large quantities in some soils especially in arid and semi-arid regions
• Salt-affected (halomorphic) soils


  Soils whose salt content is high enough to cause negative effect on plant growth
• Types of halomorphic soils

  • Saline
  • Alkaline
  • Saline-alkaline
• Saline soils


  • Electrical conductivity (of saturation extract) greater that 5 MS Cm-2 (4 million hos/cm) or 4 decisiemens per meter (4ds/m)
  • Low sodium absorption ratio (SAR) at 250C
  • Soluble sodim content of less than half the total soluble cations
  • pH value usually between 6.3 – 8.5
• Alkaline (sodic) soils


  • Sodium content or Na saturation is greater than 15%
  • Exchangeable sodium percentage (ESP) or sodium adsorption ratio (SAR) is greater than 15%
• Saline-alkaline soils


  • Electrical conductivity > 4mmhos/cm
  • Exchangeable sodium percentage (ESP) > 15%
  • pH value of less than 8.5
• General features of halomorphic soils

  • pH usually high, between 7.5 and 10
  • Deficiency of micronutrients like Zn, Cu, or Mn
  • Decrease in permeability and pore-space in alkaline soils
  • Clay and organic matter particles dispersed or deflocculated
  • Surfaces dry out into large massive hard clay pan
  • Precipitation of insoluble calcium phosphates
  • Toxicity of Na+, OH- and HCO3- ions
• Reclamation and management of halomorphic soils

  1. Establish appropriate drainage systems

  2. Leach out excess salts

  3. Apply amendments like gypsum, sulphur, or acid-forming fertilizers

  4. Improve soil structure and permeability

  5. Grow salt-tolerant crops
• Basic calcium phosphates


  • Carbonates apatite Ca10 CO3 (HPO4)6
  • Hydroxylapatite Ca10 (OH)2 (HPO4)6
• Soil alkalinity affects plants

  Due to the toxicity of the Na+, OH- and HCO3- ions
• Hydrolysis of sodium carbonate in soil

  Na2 CO3 + CO2 + H2O -> 2Na+ + 2HCO3-
• Extreme alkalinity


  pH 8.5 - 10.5 or higher, due to the presence of Na2 CO3
• Black colouration of soil surface

  Due to the dispersed humus carried upward by capillary water
• Irrigation water containing excess Na+ and HCO3-

  Often causes soil alkalinity
• In soils of high pH, many nutrients become unavailable and the unstable structure leads to low water permeability, poor aeration and unworkable silts
• Establish Appropriate Drainage Systems

  1. Pumping

  2. Tile drains

  3. Drainage ditches

  4. Canals

  5. Deep ploughing to improve soil permeability
• Leaching Excess Salt


  Heavy application of low salt irrigation water to leach excess salts out of the root zone
• In warm arid regions, accumulation of salts can be very substantial, so irrigation schemes must be well managed to remove excess salts regularly from the root zone</b>