02 July 2019


Addressing soil loss

By Aspire IAS

Addressing soil loss

Floods often wash away rich, weathered soil and the gradual loss of soil productivity can have a lasting impact on the local economy. The rehabilitation programmes often fail to consider this loss. In the case of Kerala and Kodagu, the undulation and force of the water would have led to severe soil and land erosion.

Impact of floods on soil:

  • Flooding impacts the nutrient levels in the soil. Flooding and long periods of waterlogging result in the depletion of nutrients.
  • Floods also result in denitrification of the soil.
  • When the upland soils are under water for days or weeks it causes oxygen depletion, or reducing conditions, which may in turn affect the chemistry of the soil-water system and, consequently, soil aggregation.
  • Loss of soil aggregation impacts agriculture by decreasing soil quality and crop production.
  • Surface crusting is an issue after flooded soils dry out.


Soil degradation due to flooding is a serious concern.

  • A 2014 review of soil degradation in India by multiple institutions shows that an estimated 14 million hectares suffer soil degradation due to flooding annually.
  • The impact of floods on soil was also studied in detail following the 2009 floods in North Karnataka. Researchers from the National Bureau of Soil Survey and Land Use Planning (NBSS&LUP) and other institutes estimate that 13 flood-hit districts lost 287 million tonnes of top soil and soil nutrients across 10.75 million hectares of farmland.
  • Under market prices, the replacement of nutrients such as nitrates, phosphates and iron would have cost Rs.1,625 crore, while another Rs.853 crore would have been spent on replenishing organic material lost. To recover and replace would take a “considerable” amount of time, and a steadfast programme of recovery, they noted.
  • Nine years later, there is no comprehensive scheme for recovery, and the effect of the floods is still visible on the ground.
  • A soil profile of a few affected districts, done under the State’s integrated watershed scheme, shows large swathes of these areas having “shallow or very shallow” soil depth, organic carbon deficiency, and low productivity of land.

 floods and Soil?

  • Not all floods are bad for the soil, as seen in the frequently occurring floods along the banks of the Ganga, Kosi, Brahmaputra and other rivers taking birth in the Himalayas.
  • There, the gushing river emanating from the mountains carries with it loosened alluvial soil, and not only washes over farmlands, but also replenishes flood plains with fertile soil.
  • However, in south and central India, floods wash away rich, weathered soil, which are deposited in reservoirs or as sand bars along the river bed or in the sea.

Way forward:

While roads and houses will be rebuilt, and crop losses compensated partially through insurance, the gradual loss of soil productivity must also be taken care of. Any rehabilitation programme must consider the lost soil.