Article 1 of the UN Convention to combat desertification defines land degradation as a “reduction or loss in arid, semi-arid and dry sub-humid areas of the biological or economic productivity and complexity of rain-fed cropland, irrigated cropland, or range, pasture, forest and woodlands resulting from land uses or from a process or combination of processes, including processes arising from human activities and habitation patterns, such as: (i) soil erosion caused by wind and / or water; (ii) deterioration of the physical, chemical, and biological and economic properties of soil; and (iii) long-term loss of natural vegetation” (Ministry of Environment & Forests, GoI, 2014).
Land can be said to be degraded when the soil suffers from decline or loss in its quality or productive capacity, whose causes can be natural or anthropic. When soil is degraded, it exhibits certain physical properties due to decline in soil structure such as erosion, desertification, anaerobism, compaction, crusting, and contamination due to pollutants.
Degraded soil also exhibits chemical properties such as fertility decline, salinization, acidification, leaching and decline in water retention. Degraded soil also has biological aspects and some of them include lessening of land biodiversity and decline in biomass carbon.
Land degradation occurs due to degradation processes that can be triggered by natural factors, which can be intrinsic such as climate, topography, vegetation and biological interactions or due to anthropic, or man-made causes. Anthropic causes for land degradation can be biophysical or socio-economic.
The biophysical causes include land use and management methods, which can range from agricultural practices such as use of pesticides to deforestation. The socioeconomic causes include issues related to the eocio-economic infrastructure directly and indirectly affecting soil quality, such as land tenure, health concerns and institutional support. Land degradation usually involves a combination these processes working in tandem.
Depending on the intrinsic properties of soil and other natural determinants such as climate and topography, soil can be highly resistant, stable, vulnerable or highly sensitive to degradation. It is estimated that one-sixth of the world’s soils have already been degraded by water and wind erosion.
This has two important consequences: a) the reduced ability of society to produce sufficient food due to loss of quality and depth of soils, and b) pollution associated with erosion.
Siltation of dams, pollution of water courses by agricultural chemicals and damage to property by soil laden runoff reduces the productive capacity of land.
The Ministry of Environment & Forests, GoI (2014) lists intensive agriculture, changes in land use, deforestation, encroachment and over-utilization of natural resources as the chief causes of land degradation.
These require sustainable land and ecosystem management. Although different methods of estimating total area of degraded land in India can lead to diverse results, the figures from different agencies have ranged between from between 55 to 188 million ha.
On June 17, 2016, the Indian Space Research Organization (ISRO) released the Desertification and Land Degradation Atlas of the entire country using Indian Remote Sensing Satellite (IRS) data in a Geographical Information System (GIS) environment.
The survey returned the result that out of a total of 96.40 Mha of land under desertification / land degradation in India in 2011-13, Rajasthan (21.53 Mha) had the highest portion of area with desertification / land degradation in 2011-13 while Sikkim (0.08 Mha) had the lowest.
The cumulative increase in desertification / land degradation between 2003-05 to 2011-13 in India was 1.87 Mha, or an increase by 0.57 per cent. The area of land converted from Degraded in 2003-05 to No Apparent Degradation in 2011-13 was 1.95 Mha.
The most startling statistic is the fact that 28.76 per cent of total land area in 2003-05 and 29.32 per cent of total land area in 2011-13 in India is land under desertification / degradation (ISRO, 2016), which is more than a quarter of the total land area in India.