Learn: Optimum use of water, water requirement,Relation between M.C. and growth rate,Relation between yield and water depth.


  • The quantity of water supplied to a particular crop during its growth period.
  • Which results in the maximum yield of the crop is known as optimum water requirement.
  • This water requirement includes water supplied by irrigation and by precipitation both.
  • In order to get the maximum yield with least amount of irrigation water.
  • Knowledge of optimum requirement of water for the crop is essential.
  • Supply of irrigation water, both more, and less than the optimum requirement, affects yield adversely.
  • If less than optimum amount of irrigation water is supplied.
  • The plant has to expend extra energy to get moisture from the soil.
  • which would otherwise have been utilised for the growth of the plant.
  • This affects the yield. On the other hand if more than optimum
  • Requirement of water is supplied it would expel the air from soil pores and fill them with water.
  • This will prevent free circulation of fresh air which is essential.
  • the metabolic activity to prepare food for the plant. This also affects yield.
  • Relation between yield and depth of irrigation water for the crops follows
  • The pattern shown in Fig. 3.2. On the same ground the relation between rate of growth of the plant
  • Moisture content of soil, can be drawn as shown in Fig. 3.1. At moisture content below

Relation between M.C. and growth rate.

  • Permanent wilting point practically no growth of the plant is possible
  • As moisture is not available from soil for this purpose.
  • As the moisture content in the soil is slowly increased.
  • The rate of growth of crop also correspondingly increases as shown in Fig. 3.1.
  • This phenomenon continues till optimum moisture content is reached.
  • After this any increase in moisture content would affect the growth adversely.

Relation between yield and water depth.

  • Thus in order to achieve maximum yield of the crop growth of the plants should be optimum.
  • Irrigation schedule should be so planned and regulated that crops receive (Fig. 3.1) only optimum
  • Amount of moisture in each watering and total depth of
  • Water supplied is as per the requirements of optimum yield, see Fig. 3.2.