Irrigation
Water is essential for all organisms, it is important for proper growth and development. Plants absorb water by their roots. Along with water minerals are also absorbed. It is necessary to maintain the moisture of the soil for healthy crop growth; therefore fields have to be watered regularly which is known as irrigation.
“The supply of water to crops at regular intervals is called irrigation. The time and frequency of irrigation varies from crop to crop, soil to soil and season to season.”
In summer, the frequency of watering is higher due to high rate of evaporation and transpiration.
Need of irrigation
Plants contain nearby 90% water. Water is very important for the growth of plants as it helps in; germination of seeds, absorption and transport of dissolved nutrients, photosynthesis and temperature regulation.
- All crops do not require the same amount of water. For example, rice requires a lot of water, while wheat requires less, and millets require even less. Beside this, different crops require water at different stage of their growth.
- Excessive irrigation is also harmful for crops since it causes water logging which check roots breathing.
Sources of Irrigation
Traditionally farmers depend on raining for irrigation. Farmers sow kharif crops in the beginning of rainy season which rarely need water from other sources rather than the rain. But rabi for crops farmers mainly depend on underground water.
The sources of water for irrigation other than rain are; wells, tubewells, ponds, lakes, rivers, dams and canals.
Methods of irrigation
Methods of irrigation depend on the availability of water and the type of crop.
Traditional methods of irrigation:
In this method of irrigation water is allow to flow on the surface of the soil in the field. This is called surface irrigation. The water available in wells, lakes and canals is lifted up by either animal’s power (in olden days) or by electric pumps (nowadays). Following are old systems which were use for lifting water from the source.
- Moat (pulley-system)
- Chain pump
- Dhekli
- Rahat (Lever system)
Modern methods of irrigation:
Modern methods of irrigation help us to use water economically. The main methods used are as follows:
- Sprinkler System
- Drip system
Sprinkler System:
This system is more useful on the uneven land where sufficient water is not available. In this system, there are perpendicular pipes with rotating nozzles on top. These pipes are joined to the main pipeline. When water flows through main pipeline under pressure with the help of a pump, it escape from rotating nozzle and gets sprinkled on the crop as if it is raining.
Drip system:
This is more efficient and popular method which is being use nowadays mainly for cultivation of fruit plants, gardens and trees. In this system, the water falls drop by drop directly near roots of the plant. Water does not waste in this system hence; it is a boon in regions where availability of water is poor.
Assignment
- Explain how fertilizers are different from manure.
- What are advantages of manure?
- In summer, the frequency of watering is higher. Why is it so?
- What is irrigation ? Describe two methods of irrigation which conserve water.
- Explain how soil gets affected by the continuous plantation of crops in a field.
- Beera, wants to practice crop rotation in his field. Suggest a Rabi crop and a Kharif crop which will replenish his field with nitrogen. Which crop replenishes nitrogen and why?