Topsoil Erosion

It’s a scary scenario. Some studies indicate that half of India’s geographical area is “degraded”, and suffers from soil erosion. On an average, the erosion rate led to an annual soil loss of over five billion tonnes. Twenty-nine percent of this loss is permanent — it flows into the seas and oceans — and 61% is merely transferred from one place to another. The remaining is deposited in reservoirs. The economic costs, which include direct ones such as production loss, loss of nutrients, and cost of salinisation and alkanisation, can be as high as Rs 45,000 crore. For example, a study revealed that “soil erosion due to water resulted in an annual crop production loss of 13.4 million tonnes in cereals, oil seeds, and pulse crops, equivalent to $162 billion”.

There are several reasons for the erosion, both natural and manmade. They include:

• In eight Indian states, overgrazing and deforestation have led to over 20% wastelands. In the case of overgrazing, the soil loss is 5-41 times the normal at the meso-scale, and 3-18 times greater at the macro-scale.

• A combination of industrialisation, urbanisation, and infrastructure development takes away considerable areas. Mining is a major cause, especially illegal mining, now that open cast mining is under control.

• “Natural causes of land degradation include earthquakes, tsunamis, droughts, avalanches, landslides, volcanic eruptions, floods, tornadoes, and wildfires.”

• Land shortage and land fragmentation, coupled with poverty “limit the use of green manuring or soil conservation structures”. Hence, they lead to “non-sustainable land management practices — a direct source of degradation”.

• Population increase, both of humans and livestock, is an obvious reason for soil erosion.

• Certain agriculture practices such as intensive farming, low use of fertilisers, excessive tillage and use of heavy machinery, burning of crop residue, poor irrigation, poor crop rotations, and soil pollution contribute to the extensive degradation of the land.