THE term land degradation signifies that the land has become less productive and supportive of human life and livestock or is less able to renew its natural vegetation. It is therefore a matter of major concern for those who care for land and environment.

In Pakistan, land degradation encompasses deforestation and desertification, salinity and sodicity, soil erosion, water-logging, depletion of soil fertility and negative nutrient balances.

Pakistan is located in arid and semi-arid climatic zones. Generally high evapo-transpiration in semi-arid and arid zones is the basic cause for salt accumulation on the soil surface. The average summer temperature is about 40°C and the minimum winter temperature remains between 2°C to 5°C. The annual rainfall varies between 100 mm to 700 mm throughout the country. The evaporation rate is generally very high and exceeds that of precipitation. Thus, the insufficient rainfall followed by high evaporative demand and shallow ground water depth, enhances the movement of salts towards soil surface that leads to salinity and erosion of the soils.

Accumulation of rain and floodwaters in natural depressions is the major cause of primary salinity. Secondary salinity due to man-made causes is related to seepage from canals, lack of drainage, use of poor quality groundwater for irrigation, and insufficient leaching and poor land management practices.

Salinity and sodicity: At country level, 6.28 million ha of the area is affected with salinity and sodicity. The majority of salt-affected soils are saline-sodic in nature. These salt-affected soils are causing potential reduction in yield.

Soil erosion: Soil erosion implies to loss or removal of surface soil material through the action of moving water, wind or ice. About 13.05 million hectares of the area is affected by water erosion and about 6.17 million hectares by water erosion. Soil erosion is taking place at an alarming rate and is mainly due to deforestation in the north. Water erosion is prominent on steep slopes such as the Potohar track and surrounding areas, an area extensively used for cultivation.

The highest rate of erosion recorded so far is at 150-165 tones/hectare/year. The Indus River carried the fifth largest load of sediment (4.49t/h) in the world in 1990. According to some estimates the Indus is adding 500,000 tones of sediment to the Tarbela Reservoir every day, reducing the life of the dam by 22 per cent and the capacity of reservoir by 16 per cent. Wind erosion has a relatively lower impact than water erosion. However, the combination of the two is more devastating. This reduces the productivity of land by 1.5-7.5 per cent per year. This affects almost one-fifth of the Punjab.

Water Logging: It appears that problem of water logging may not be as serious now as it was in the past. The problem has reduced due to prolonged drought and excessive mining of ground water.

The extent of the mentioned problems in terms of area is presented in the table below.

All of the above environmental issues are summarily heading Pakistan towards more economic instability. According to a conservative estimate, the impacts of degradation and biodiversity loss on productivity and public health are in the tune of three per cent of GDP per year. It would be higher if toxic waste disposal, biodiversity, river and coastal resource depletion were taken into account.

It is, therefore, necessary for the sustainable economic future of the country and a friendly environment to cope with land degradation problem on war-footing.. Productive lands and healthy environment are the only gift worth passing to our next generations.