More and more water

 
Last Updated: Sunday 28 June 2015

More and more water

-- A third factor has led to the current debility of soils in India: irrigation. That is to say, water over-use. To feed the rice-wheat mentality, net irrigated area rose from 20.8 million ha in 1950 to 53.5 million ha in 1995-1996. Fed on irrigation, the agricultural area grew from a mere 20.8 per cent in 1966-1967 to 42.4 per cent of the 120 million ha of cultivated land in the country by 1997-1998. Canals began to weave their way through the land, bringing subsidised water right up to the farm-gate. Farmers went on a flood; then began to suffer.

Take the case of Ram Pal, of village Kalwala in Bhatinda district, south Punjab. He has a family of three to feed and aRs 50,000 debt. His only asset -- 3.6 acres of land -- has turned saline. "What is the use of living when our only source of income is gone?" Ram Pal is just one of the many villagers in Punjab whose land is swamped with saline water. Waterlogging, caused by irrigation without drainage, leads to high rates of evaporation. With evaporation, salts in the water settle on the soil. This leads to salinity or alkalinity of the soil. (see map: A big pinch; also see table: A bigger pinch). As the salt content increases, the soil-plant system registers a reverse osmosis process. Due to osmotic pressure, plant roots tend to lose water and nutrients instead of absorbing them from the soil.

A classic example of this is the Kolhapur region in Maharashtra. Farmers took to cultivating sugarcane, a water-guzzling crop with many buyers in sugarmills around the area. About 65 per cent of the irrigation potential in the region is diverted to supporting sugarcane, which covers just three per cent of the cultivated area. The region's fine-grained black soil does not allow penetration of water, leading to salt build-up. Salt in the soil increases by 20 to 25 tonnes per ha after a single sugarcane crop. The result: lower yields of sugarcane on the same land.

A bigger pinch
Canal command areas display high salinity
Project Waterlogged
area
(1000 ha)
Percentage
of command
area
Saline area
(1000 ha)
Percentage
of command
area
Ramganga 195 10 352 18
Gandak 562 53 400 38
Nagarjuna 114 24 69 14
Sharda 260 7 253 7
Chambal 99 20 40 8
Mahi 89 39 61 29
Source: Singh, N T, Dryland Salinity in the Indo-Pakistan subcontinent, Universitat Bonn, 2000. Map source: Wastelands Atlas of India, ministry of rural development, 2000

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