Crop Seasons, Duty , Delta and Base Period

    Crop Seasons

• The period of time i.e. duration of raising

the crops in the soil is known as crop

season.

• Three normal season occurs in India.

(i) Summer or Kharif Season- April-September

(ii) Winter or Rabi Season-Oct-March

(iii) Monsoon Season-June-August

               Duty of Water (D)

• The area irrigated by an average

discharge of one cumec for a specified

number of days is called duty of water.

• It is denoted by ‘D’.

• It is expressed in hectare per cumec.

                                  Delta

• The depth of water required per hectare

for the full growth of the crop is called

delta.

• It is expressed in centimetre of water.

• It is denoted by ∆.

                    Base Period

• The time between the first watering of a crop at the time of its sowing and its last watering before harvesting is called the base period of the crop.

• It is expressed in days.

• It is denoted by ‘B’

Relationship Between Duty, Delta and Base Period

• Let the crop base period = B days

• Amount of water applied to this crop = 1 cumec

• Therefore volume of water applied to this crop for B days i.e. V = 1 cumec X B

= (m3 x 60 x60 x24 X B sec)/sec

= 86400 X B m3

• By definition of duty, quantity of water will mature D hectare of land = 104 X D m2

• Therefore, total depth of water applied on this area= Volume/ Area

= 86400 X B m3/ 10^4  X D m^2                where (10^4 Ten raise to power 4)

= (8.64 B / D) m

This total depth of water is called delta (∆).

Therefore, ∆= (8.64 B / D) m 

            ∆= (864 B / D) cm