A recent UN study has found that 20 per cent of all irrigated lands globally, an area equal to the size of France, has already been spoiled by increasing levels of salt concentration in the soil
The world’s population is expected to touch nine billion by 2050 and the Food and Agriculture Organisation of the United Nations envisages the need to increase food production by 70 per cent, including a 50 per cent rise in annual cereal production (to about three billion tonnes) in order to meet the population growth. This quantum leap in food production efficiency requires a robust framework that accommodates the rising population and simultaneously guarantees availability of food without compromising on quality of sustainable agricultural practices. The current global gap between demand and production of food cannot be allowed to grow, and any hurdle enroute to a food-secure future must be identified and resolved on an immediate basis.
One of the major hurdles in achieving superior food production capability is the growing problem of soil salinity and the resultant lack of cultivable land. The FAO and the United Nations Educational, Scientific and Cultural Organisation estimates put the world saline soil at 397 million hectare and sodic soil at 434 million hectares. About 12.6 million hectare is considered to be under acid-sulphate soil, distributed along the coastal region. A recent study conducted by the United Nations University reveals a grim scenario as 20 per cent of all irrigated lands globally, an area equal to the size of France, have already been spoiled by increasing levels of salt concentration in the soil.
The study also revealed that over a period of 20 years, an average of 2,000 hectare of irrigated land in arid and semi-arid areas across 75 countries have been degraded by salt concentration. This land degeneration has cost $27 billion in lost crop value per year. In India, the problem has manifested itself in the Indo-Gangetic Basin, which has suffered soil degradation causing crop yield losses for wheat by 40 per cent, rice by 45 per cent, sugarcane by 48 per cent andcotton by 63 per cent respectively. In addition, the employment losses could be 50 to 80 man-days per hectare, with an estimated 20 to 40 per cent increase in human health problems and 15 to 50 per cent increase in animal health problems.
Salt-induced land degradation is a serious problem that occurs in arid and semi-arid regions where rainfall is too low to maintain regular percolation of rain water through the soil and where irrigation is practiced without a natural or artificial drainage system. Irrigation practices without drainage management trigger the accumulation of salt in the root zone, affecting several soil properties and reducing productivity.
A large portion of affected areas in the developing countries have seen investments made in irrigation and drainage but infrastructure is not properly maintained or managed. India is no exception due to the lack of aggressive initiatives to reclaim degraded saline lands. Though the Indian crop yields from irrigated areas that are not affected by salinisation have increased since 1990, however the same cannot compensate for increasing yield loss that occurs due to salt degraded lands.
Degraded land is posing an environmental risk as well due to the green house gas that is emitted, therefore, there is an urgent need to address the issue by applying mitigation techniques that have proven successful across the world in reversing land degradation.
The reversal of degradation and the consequent reclamation of lands should be driven by customised hydrological models that facilitate reduction of abnormally high level of salt in the soil through methods such as leaching. Agricultural practices in the affected regions must incorporate tree planting and functional drainage network that prevent accumulation of salt at root level.
Awareness generation on significance of deep plowing must be instilled in farming community as it helps in bringing down salt level in the soil. Kisan call centers that currently provide assistance on various aspects of farming must also offer advisory to the farmer on cultivation of salt-tolerant varieties of crops besides information on how to mix harvested plant residues into top soil. Yet another simple but highly effective method to counter undesirable salt level is to dig a drain or deep ditch around the affected land, this facilitates the flow of water to the drains from root level thereby carrying away excess quantity of salt.
The Government must step in to help the farming community financially as the investment cost to prevent and reverse land degradation, or to restore degraded land into productive land is very high. The Government can also devise pertinent policies, well-designed salinity management plans, besides capacity development of farmers in order to combat salt-induced land degradation.