(1) It acts as a solvent for the nutrients1 Water forms the solution of the nutrients and this solution is absorbed by the roots. Thus, water acts as the nutrient carrier,
(2) The irrigation water supplies moisture which is essential for the life of bacteria beneficial to the plant growth.
(3) Irrigation water supplies moisture which is essential for the chemical action within the plant leading to its growth.
(4) Some salts present in soil react to produce nourishing food products only in the presence of water. Q.3: Define the term crop period. Ans : Crop period is the time, in days, that a crop takes from the instant of its sowing to that of its harvesting Q.4: Define the term base period. Ans : Base period for a crop refers to the whole period of cultivation from the time when irrigation water is first issued for preparation of the ground for planting the crop, to its last watering before harvesting. Q.5: Write down the necessity for rotation of crops. Ans : The necessity for rotation arises from the fact that soil gradually losses its fertility if the same crop is sown every year and the field has to be allowed to lie fallow in order to regain its fertility. The effect of fallow is obtained by rotation of crops. Q.6: Write down the difference between duty and delta. Ans : Duty represents the irrigating capacity of a unit of water and Delta is the total depth of water required by a crop during the entire period the crop is in the field and is denoted by the symbol delta Q.7: Write down any four factors affecting on duty (1) Methods and system of irrigation
(2) Mode of applying water to the crops
(3) Methods of cultivation
(4) Time and frequency of tilling Q.9: Define the term high and low duty. Ans : Duty is being referred to as being high or low according to the number of hectares/cumec irrigated is large or small.
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