Soil Fertility and Nutrient management (1+1)

II. Application of fertilizers in Liquid form

• Solid form of fertilizers with known concentrations are dissolved in definite volume of water and sprayed over the leaves. Commercially liquid fertilizer solutions are available in the market may be applied to the plants or soil directly. Various methods are used to apply the fertilizer in liquid form.

  i) Starter solution: Fertilizer solutions are prepared by dissolving the fertilizers in water at the ratio of 1:2:1 or 1:1:2 of N: P2O5: K2O and applied to young vegetable plants at the time of transplanting. It is used in place of watering which helps in better establishment & early growth of plants. Only small amount of fertilizer is needed.
  ii) Foliar application: Spraying over the leaves of growing plants with suitable fertilizer solutions of lower concentrations (recommended) to supply one or combination of nutrients. Most of the micronutrient fertilizers (Zn or Boron) are applied as foliar spray and urea is also used for foliar spray.
  iii) Direct application of Liquid fertilizers to soils: Liquid anhydrous ammonia or N, P, K fertilizers are applied to soils (10 cm depth) with the help of special equipment. Plant injury or wastage of ammonia is very much limited.
  iv) Fertigation: It is the process of direct application of liquid fertilizers through irrigation water. Straight and mixed fertilizers of N P K which are easily soluble in irrigation water can applied through furrow or drip irrigation or sprinkler irrigation system.

  Advantages of liquid forms of fertilizers

  1) Under acute deficiency of elements like N, P, K, and micronutrients during active growth period of plants can be corrected.
  2) Rapid plant absorption, quick response and for fruit trees more efficient and effective method.
  3) Along with fertilizer solutions we can apply insecticides and herbicides with sticking agents and also some soil amendments like lime and gypsum.
  4) Small amount/concentration of nutrients can be used.

  Disadvantage of liquid forms

  1) Sometimes fertilizer solutions causes scorching or burning of leaves due to presence of acids in it like ammonium sulphate or chlorides in KCl fertilizer
  2) It is more expensive/ costly.
  3) Several applications are needed for moderate to high fertilizer rates.
  4) All the fertilizers cannot be applied. Ex: Ammonium sulphate is unsuitable for foliar spray.
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