India has lost over 1,500 sq km of land to ‘catastrophic’ soil erosion

GS Paper III

News Excerpt:

A new study has revealed a worrying trend for India’s soil health. Nearly 30% of the country’s landmass is experiencing “minor” soil erosion, while a critical 3% faces “catastrophic” topsoil loss.

About “Geospatial Modelling and Mapping of Soil Erosion in India” study:

  • It classified soil erosion across India for the first time. Before this study, there was no classification for different levels of soil erosion in India.
    • Soil erosion is a process that removes the upper layer of soil, from which plants get most of their nutrients and water. It is the most common type of land degradation.
  • The study used the Revised Universal Soil Loss Equation (RUSLE) equation.
    • It considers factors such as predicted crop loss, rainfall and runoffs, also known as the R-factor, soil erodibility, slope steepness and length, crop management, and support practices like strip cropping, etc., to estimate soil loss at a 250-metre spatial resolution.
  • The study developed six classifications for soil erosion, ranging from "minor" to "catastrophic", regarding soil eroded in tonnes over a hectare per year.
  • The Brahmaputra Valley in Assam is India's biggest hotspot for soil erosion. The state has lost nearly 300 square kilometres or 31% of its surface soil to "catastrophic" erosion.
  • The lower reaches of the Himalayas, which are characterised by loose soil and unstable slopes, are another hotspot.
    • The region spans from the Kashmir Valley to the southern regions of Himachal Pradesh and Uttarakhand and extends across the border into Nepal and parts of Odisha.
    • This region is one of the most prominent erosion hotspots in the country, exacerbated by its susceptibility to seismic activity.
  • Odisha is also a hotspot for "catastrophic" erosion.
    • This erosion extends from the southern reaches of the Mahanadi River, traversing along the western borders of the state's lush green cover and natural forests, all the way to the northern parts of Andhra Pradesh.
    • This underscores the significant soil degradation experienced by the forest cover in the region.
  • The study highlighted that nine out of the country's 20 most susceptible districts to soil erosion are located in Assam.
  • The national mean for soil in the country stood at 21 tonnes per hectare per year.

Significance of the study:

  • It provides a holistic view of soil status and would help in the planning of soil conservation.
  • The data gathered would be available for anyone to use in the future.

Implications of the erosion:

  • According to the Food and Agriculture Organization of the United Nations, it could take up to 1,000 years to produce 2 to 3 centimetres of top or surface soil, which has a depth of 6 cm.
  • Topsoil — the uppermost layer of soil —  is vital for agriculture as it holds nutrients and moisture essential for plant growth.
  • Erosion significantly reduces fertility and can lead to decreased crop yields.

Causes and Effects of soil erosion:

Soil Erosion vis-a-vis Climate Change:

  • Erosion degrades land, which means it can support fewer plants that can take in climate-warming carbon dioxide.
  • Soils themselves could potentially sequester enough greenhouse gases in a year to equal about 5% of all annual human-made GHG emissions.
  • On the flip side, unchecked climate change can worsen erosion.
    • A report from the Intergovernmental Panel on Climate Change (IPCC) found that when cultivated without conservation practices, soil is currently eroding up to 100 times quicker than it is forming.
    • Due to emissions-driven temperature changes, the risk of erosion will become even higher in the future, resulting in decreases in agricultural production, land value, and human health.

Way forward:

  • Use soil-friendly agricultural practices:
    • Terraced farming needs to be implemented to make hillside agriculture manageable. Terraces prevent erosion and allow more water to flow to crops.
    • In addition, hillside farm fields need full crop cover to help keep the soil in place. This can be accomplished by intercropping, which means growing two crops together in the same field, such as planting rows of maize or soybean between rows of oil palm trees.
    • For smallholders, agroforestry systems where diverse crops, including trees, are grown together can be effective.
    • Access to manure improves the organic matter of the soil, inhibiting erosion.
    • Finally, alternating deep-rooted and shallow-rooted crops improves soil structure and reduces erosion.
  • Offer incentives for land management:
    • Governments and banks must help farmers access credit and support in implementing erosion prevention. The cost of erosion prevention is far lower than the price of land restoration and rehabilitation, which one source estimated to be around $1,500–$2,000 per hectare. Another source found it could reach $15,221 per hectare.
    • Better land management can help keep soils intact so they can grow more carbon-sucking vegetation. This is already happening in China, where the Grain-for-Green project in the Yellow River basin conserved soil and water and reduced carbon emissions.
  • Prevention and Rehabilitation:
    • The key to managing and reducing soil erosion is to rehabilitate already damaged land, stop further degradation, and make erosion-preventative measures the core of land management policy.

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