Question

1. Why do we need to adopt different means of irrigation?
2. Mention the three factors based on which different means of irrigation are used.
3. Name the states in India where well irrigation is used.

Answer 1

Hint: Water is an essential substance for the survival of living organisms including crop plants. Irrigation refers to the process of supplying water to crop plants artificially in order to satisfy their water needs. In the process, nutrients may also be provided. There are various water sources available for the purpose of irrigation like ponds, lakes, canals, tube-wells and even dams.

Complete answer:
1. To select an irrigation method, the farmer must be aware of the advantages and disadvantages of the various methods. Testing of the various methods under the existing local conditions suggests the best basis for a good choice of irrigation method. It is very important, as a bad choice would cause the crops to perish and the farmer will incur losses.

2. The suitability of the different means of irrigation depends primarily on the following three factors.
i) Natural conditions
Soil type- Sandy soil has very minute particles and hence, possesses a low water storage capacity and a high infiltration rate, and therefore it requires frequent but small irrigation applications. Under these conditions, the sprinkler or drip irrigation method is more suitable as compared to surface irrigation. On loam or clay soils all the 3 methods of irrigation can be used, but generally, surface irrigation is seen. Clay soils having low infiltration rates are best suited to surface irrigation.

Slope- On steeper or unevenly sloping lands, Sprinkler or drip irrigation is preferred above-surface irrigation because they require little or no land levelling. An exception to this is rice grown on terraces on sloping lands.

ii) Climate: Under very windy conditions, drip or surface irrigation methods are given preference, as strong wind can disturb the spraying of water through the sprinklers.
Water availability & quality

When there is a short supply of water, sprinkler and drip irrigation are preferred because of their high water application efficiency. If the irrigation water contains many sediments then surface irrigation is preferred because the sediments can clog the drip or sprinkler irrigation systems. If the irrigation water contains dissolved salts, drip irrigation is adopted, as less water is applied to the soil in comparison to surface methods. In the case of leaching out salts, sprinkler systems are more efficient.

iii) Type of crop- Surface irrigation is suitable for all types of crops. Sprinkler and drip irrigation are mostly used for high-value crops because of their high capital investment per hectare. They are rarely used for the lower value staple crops. Drip irrigation is used for irrigating individual plants or trees or row crops like vegetables and sugarcane. It is not adopted for close-growing crops (e.g. rice).

3. The method of well-irrigation has been used in India from way back in the past. Various methods are employed to lift the groundwater from the well for irrigation. Uttar Pradesh has the largest area i.e. 93-84 lakh hectares under well- irrigation accounting for 28-19 percent of the well irrigated areas in India. This is followed by states like Rajasthan, Punjab, Madhya Pradesh, Gujarat, Bihar, Andhra Pradesh, Maharashtra, Haryana, Tamil Nadu, West Bengal and Karnataka that use well irrigation.

Note: The first tube well of India was sunk in 1930 in the state of Uttar Pradesh. More than three-fourths of India’s tube wells are functioning in the states of Tamil Nadu, Maharashtra, Andhra Pradesh, U.P, M.P, Karnataka and Punjab. Tamil Nadu possesses 11 lakh tube wells which is the largest number in the country.