SSC 2 MIDTERM REVIEWER

• Crops


  Differ in their total nutrient requirements even in the rate of supply at different growth stages
• Quantitative methods to assess nutrient needs of a crop

  • Laboratory Soil Test
  • Plant Tissue Analysis
  • Fertilizer Field Trials
• Qualitative methods to assess nutrient needs of a crop

  • Visual symptoms of nutrient deficiency in plants
  • Soil Test Kit
  • Microbiological Method
  • Diagnostic Procedures (Qualitative & Quantitative)
  • Procedures of determining amounts of nutrients needed (Fertilizer Calculation)
• Nutrient deficiency symptoms


  Certain color development in leaves and certain changes in growth that vary from crop to crop and with the degree of deficiency
• Nutrient deficiency may lead to poor growth, low yield, and in extreme cases, the death of crops
• Reasons for nutrient deficiencies

  • Insufficient amount and supply of soil nutrients
  • Unavailability of forms of nutrients present
  • No proper balance among nutrient levels
• Using visual diagnosis of nutrient deficiency symptoms

  • Requires experience
  • Some symptoms are difficult to identify
  • Plants may not show hunger signs unless deficiency becomes acute
  • Abnormalities in plants may not always mean nutrient deficiencies
• Characteristics of nutrient deficiency

  • Appear in patches
  • Appear in a certain pattern
  • Specific and unique
• Identification of nutrient deficiencies


  1. Conditions of occurrence

  2. Pattern of appearance

  3. Specificity of the symptom

  4. Stages of development
• Nutrient deficiency symptoms appear in patches due to reasons like root-infesting nematodes and pathogens causing root rot and wilt
• Nutrient deficiency symptoms appear in a certain pattern depending on the mobility of the nutrient in the plant body
• Nutrient deficiency symptoms are not always specific and unique, as they can be similar to symptoms caused by other factors
• All four parameters (conditions of occurrence, pattern of appearance, specificity of the symptom, and stages of development) should match to conclude a diagnosis of nutrient deficiency
• Conditions that can cause nutrient deficiencies

  • Regular heavy rains in light-textured, low-organic-matter, well-drained soils leading to nitrogen deficiency
  • Recently levelled lands leading to zinc deficiency
  • Heavy and excess application of phosphatic fertilizers causing zinc deficiency
  • Heavy and excess application of potassium fertilizers causing magnesium deficiency
  • Excess application of urea causing calcium deficiency
  • Over-liming of acid soils causing iron deficiency
  • Molybdenum deficiency in acid soils with pH below 6.5
  • Iron deficiency in alkaline soils with pH above 7.5
  • Deficiencies of phosphorus, potassium, sulfur, calcium and magnesium in acid soils with pH below 6.0
  • Waterlogged conditions causing phosphorus deficiency
• Nutrient deficiency symptoms appear in a definite pattern, with deficiencies of nitrogen, phosphorus, potassium and magnesium appearing first on lower leaves and proceeding upwards, while deficiencies of calcium, sulfur, iron, manganese, copper, boron and molybdenum appear first on upper leaves and proceed downwards
• The pattern of appearance is one of the strongest tools in the visual diagnosis of nutrient deficiencies
• Specific symptoms


  Characteristic symptoms that are specific to a particular nutrient deficiency in a plant
• Developmental stages of nutrient deficiency symptoms

  • Mild deficiency condition with only one or two stages visible
  • Severe deficiency condition with all developmental stages visible
• Interveinal chlorosis


  • Yellow chlorosis develops in the interveinal tissues (tissues between the veins), leaving the veins green and prominent
• Interveinal chlorosis is a characteristic symptom of the iron deficiency in maize
• Close observation of specific symptoms is the most important part of visual diagnosis
• 'Close-up' pictures and description of 'specific' symptoms for every nutrient deficiency are helpful in identifying nutrient deficiency
• Stages of nutrient deficiency development

  1. Mild deficiency - only one or two stages visible

  2. Severe deficiency - all developmental stages often found at a time
• Stages of iron deficiency in maize

  1. Stage I: Temporary fading of interveinal tissues with prominent green veins

  2. Stage II: Pale-yellow chlorosis develops in interveinal tissues, veins green and prominent

  3. Stage III: Prominent green veins also fade and become light green to pale yellow

  4. Stage IV: Entire leaf bleaches to papery white
• Developmental stages are specific and their presence further confirms the nutrient deficiency
• Supportive tools for nutrient deficiency diagnosis

  • Digital soil pH meter
  • Soil fertility survey reports and maps
  • Indicator weeds
• Digital soil pH meter

  Measures soil pH in situ, on the spot
• Soil pH affects the availability of nutrients to the plant
• Soil pH and nutrient availability


  • Sufficiently available (pH 6.0-8.0)
  • Moderately low availability (pH 5.5-6.0 and 8.0-8.5)
  • Severely low availability (pH below 5.5 and above 8.5)
• Soil fertility survey reports and maps give the primary idea and knowledge of the probable deficiency problems of an area
• Indicator weeds


  Common weeds that clearly indicate the nutrient deficiency conditions of the field, especially helpful for crops with strong hidden hunger
• No correction treatment should be given in the entire field without proper confirmation through soil analysis and plant analysis
• Soil Test Kit (STK)

  A less costly and rapid procedure that results in the qualitative interpretation of the relative amounts of plant nutrients
• Microbiological methods


  Used for approximating the degree of deficiency of element using the growth of test organisms as indicator
• Microbiological methods


  • Azotobacter plaque method (for P, K, Ca)
  • Aspergillus niger method (for K, Mg, Zn, Co)
• Laboratory soil test


  Quantitative diagnostic technique that provides a scientific basis for formulating a sound fertility management practice
• Kjeldahl Nitrogen


  Method to determine the amount of nitrogen contained in organic material
• Plant tissue analysis


  Reveals the available nutrients status of the soil on which the plant is grown
• Fertilizer field trials are the most reliable method to assess the effect of fertilizers and their interactions with all existing factors of crop growth and development
• Fertilizer recommendations formulated through field trials are generally more realistic and dependable than previous methods