The menace of land erosion
Soil is virtually a non-renewable natural resource that needs to be guarded at all costs
Consider these dismal facts:
About 120 million hectares, or nearly 37 per cent, of the country’s total land is degraded in varying degrees; much of it due to water erosion.
On an average, about 1,535 tonnes of soil is lost from every square km land every year due to erosion.
About 5.37 to 8.4 million tonnes of plant nutrients are also lost annually along with the wasted soil.
Nearly 13.4 million tonnes of potential crop output, valued at over ~205.32 billion at 2015-16 prices, fails to materialise due to land erosion every year.
These estimates have been quoted in a policy paper on land degradation issued recently by the National Academy of Agricultural Sciences (NAAS). The gravity of these numbers can be appreciated better when viewed against the backdrop that it takes 200 to 400 years for natural evolution to form one centimetre layer of soil and another 3,000 years to make it fertile. But once destroyed, the soil is lost forever. Therefore, soil is virtually a non-renewable natural resource that needs to be guarded at all costs. That, unfortunately, is not happening to the desired extent at present though several soil and water conservation programmes based, quite appropriately, on the watershed development principles are underway.
Conservation of land and, more so, its physical, chemical and biological health is imperative also because it is finite and is qualitatively deteriorating while its demand for various development purposes is growing. Net cultivated area is more or less stagnant at 140 to 142 million hectares (ha) for a long time. Per capita land availability has declined from 0.90 ha in 1951 to a mere 0.27 ha in 200708 and is projected to shrink further to barely 0.19 ha by 2050. Worse still, the per-head availability of arable land has diminished between 1961 and 2013 from 0.34 ha to less than 0.12 ha. This is far below the threshold of two ha per capita of unirrigated land or one ha of irrigated land needed for subsistence.
The NAAS paper, titled “Mitigating land degradation due to water erosion”, points out that climate change is gradually exacerbating the hazard of land degradation. The annual rainfall in the Indian subcontinent is projected to rise by 10 per cent in terms of quantity as well as intensity by 2050. In fact, some evidence of an increase in the incidence of extreme weather events, such as exceptionally heavy showers and cloud bursts, is already noticeable. Studies quoted in the policy paper show that every one per cent accentuation in rainfall intensity can potentially increase its soil erosion power by two per cent. This makes land in India all the more vulnerable to the adverse fallout of climate change, boding ill for food as well as environment security.
A greater emphasis and higher spending on soil and water conservation programmes is desirable for other reasons as well. Apart from ample returns on investment, these programmes offer multiple benefits such as increase in crop productivity, generation of more employment, rise in farmers’ income, reduction in poverty and augmentation of groundwater resources. A comprehensive assessment of 636 watershed development projects has shown that they generate additional employment of about 151 man days per ha, increase cropping intensity (number of crops per year on the same land) by over 35 per cent, reduce water run-off by 45 per cent and cut down soil loss by 1.1 tonne per ha per year. The mean internal rate of return from the investment on watershed-based soil and water conservation programmes has been estimated at 27.4 per cent — sufficient to justify higher budgetary allocations for these programmes.
These benefits can accrue only if land is put to proper use according to its attributes. Its wrongful use can hasten its degradation. Cultivable land should normally not be used for non-farm purposes except under exceptional circumstances. River catchment basins should also not be disturbed much. What is needed, therefore, is a well-judged land use policy based on its capability categorisation.