The soil which is saturated with water is called water logged soil and this problem is called water logging.
Causes of water Logging
Pakistan has one of the best canal systems in Pakistan. It is composed of 40790 canal miles. But some defects wete found. It has created the twin problems of water logging. Some of the causes are:
- These canals were not lined during construction. Therefore, seepage of water took place. It raises the water table of soil.
- Our farmers have adopted unscientific irrigation system. Most of the water is collected in the ditches in the field. It causes water logging.
- Monsoon rain and frequent floods form small lakes and ponds also cause water logging. There is a lack of drainage system. Thus this accumulated water can not be drained out. This water gradually seeped downwards and reached the water table. Thus it raises it ground water surface.
Affects of water logging
There are following affects of water logging and salinity:
- Water logging and salinity destroy the soil structure. Different layers of the soil are badly affected.
- The soil is saturated with water. Therefore, the oxygen content of the soil is decreased. Thus oxygen is not available to the roots of the plants for respiration. So the plants die.
- It causes anaerobic condition in the soil. Thus anaerobic microorganisms are produced in It. The anaerobic microorganisms produce methane (CH4) and hydrogen sulphide (H2S). These gases produce foul smell. They make the soil unfit for other beneficial soil organisms.
- The number of aerobic organisms is reduced in waterlogged soil. It reduces the decomposition of the organic matter of the soil. It causes deficiency of nitrogen in the waterlogged soil.
- It causes deflocculation of soil. Water causes leaching of the soluble salts. Thus the upper Soil layer is without nutrients.
- The soil pH become high and osmotic pressure is increased. It badly affects the plants and other soil organisms.
- Waterlogging is also injurious to public health. Mosquitoes and flies breed in waterlogged area. They spread malaria and other water borne diseases.
- The farmers cannot construct their houses in waterlogged areas. The houses sink in the ground in these areas. Waterlogging also destroying the houses in villages, towns and cities. Cities of Peshawar and Faisalabad are badly affected by these problems.
Affects of water logging in Pakistan
Most of the plants cannot grow in waterlogged and saline conditions.
Therefore, most of land of Pakistan has become barren. Water logging is destroying our irrigated lands rapidly. It can be compared with the cancer in the human body. We are unable to achieve self-sufficiency in food due to waterlogging. Most fertile and valuable lands of the country have wasted. The farmers are facing innumerable problems. It is badly affecting our economy. Waterlogging is affecting our lands at the rate of an acre a minute. According to a rough estimate it is affecting our lands at the rate of 1 lakh acre every year. There are total forty million acres of our irrigated areas. 5 million acres are seVerely affected by salinity. 12 million acres are suffering from salinity patches. 15 million acres are poorly drained or waterlogged.
Reclamation of soil from waterlogging
Following measures usually can be taken to check and reclaim the waterlogged soil.
- Canals should be lined in order to prevent the seepage of water.
- Installation of tube well is the most effective method of reclaiming the lands. The tube wells draw water from the land. They lower the water table. Tube wells are very beneficial in the localities where subsoil water is suitable for irrigation. It gives dual benefit. Firstly water level is lowered and secondly crops cam be irrigated by the water. In some localities, tube well water is brackish. This water can be mixed with canal water for irrigation purposes.
- Effective drainage system prevents the rise of the water table. These drains carry away saline water. Thus new drainage canals should be constructed and the older ones should be made efficient.
- Bed rocks should be broken for gravitational drainage.
- Irrigation should be done on scientific lines. Research should be carried out to determine the consumptive use of water by different crops. It can prevents loss of water through percolation to the deeper layers
- Farm manure should be used at the rate of 10-20 tons per acre. This manure is composed garbage from the towns. It improves the soil structure porosity and nutrition. Gypsum is also beneficial for improving the soil structure.
- Trees should be planted along both sides of the canals up to 500 feet. They reduce the seepage of water from the canal bank.
- Rice, sugarcane, and barscen can be grown in waterlogged soils.
Reclamation of soil in Pakistan
WAPDA has started different reclamation projects under the SCARP (Salinity Control and Reclamation Project). It is estimated that about 7 to 8 million acres of land has been reclaimed throughout Pakistan. In these localities water table has gone down and waterlogging has been eliminated. Crop acreage and crop yields have increased in these areas.