II. Plant Analysis

II. Plant Analysis

  • It is a valuable supplement to soil testing in the task of soil fertility evaluation. Plant analysis indicates the actual removal of nutrients from the soil and identifies nutrient status of plant and deficiency of nutrient element. It is a direct reflection of nutrient status of soil.
    Advantages of plant analysis are
      a. Diagnosing or confirming the diagnosis of visible symptoms
      b. Identifying hidden hunger
      c. Locating areas of incipient (early stage) deficiencies.
      d. Indicating whether the applied nutrients have entered the plant
      e. Indicating interactions or antagonisms among nutrient elements.
    Plant analysis consists of three methods
  1. Rapid tissue tests: It is a rapid test and qualitative or semi quantitative method. Fresh plant tissue or sap from ruptured cells is tested for unassimilated N, P, K and other nutrients. The cell sap is added with certain reagents to develop color. Based on intensity of color low, medium and high color is categorized which indicates the deficiency, adequate and high nutrients in the plants respectively. It is mainly used for predicting deficiencies of nutrients and it is possible to forecast certain production problems.
  2. Total analysis: It is a quantitative method and performed on whole plant or on plant parts. The dried plant material is digested with acid mixtures and tested for different nutrients quantitatively by different methods. The determination gives both assimilated and unassimilated nutrients such as nitrogen, phosphorus, potassium calcium, magnesium, suphur, iron, manganese, copper, boron, molybdenum, cobalt, chlorine, silicon, zinc, aluminum etc., in plants. Recently matured plant material is preferable for accurate analysis.
    Critical levels of nutrients in plants

    Element

    General range (%)

    Critical level (%)

    N

    2.0 - 4.0

    <2

    P

    0.2 - 0.5

    <0.1

    K

    1.5 - 3.0

    <1.0

    Ca

    0.5 - 3.0

    <0.1

    Mg

    0.2 - 0.5

    <0.2

    S

    0.2 - 0.5

    <0.15

    Fe

    50 – 150 ppm

    <5 ppm

    Cu

    5 – 20 ppm

    <4 ppm

    Zn

    20 – 100 ppm

    <15 ppm

    Mn

    20 – 500 ppm

    <20 ppm

    B

    2 – 100 ppm

    <20 ppm

    Mo
      1. - 2.0 ppm

    <0.1 ppm

    Cl

    0.2 - 2.0 ppm

    -
Last modified: Wednesday, 7 December 2011, 5:38 AM