Global status of Black Soils

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Recently,  the Food Agricultural Organisation (FAO) released the Global status of black soils Report on the occasion of World Soil Day.

Key Points

• About World Soil Day: 
  • World Soil Day is celebrated on December 5, 2022.
• Threat to Black Soil and food security: 
  • Black soils feed the global population and are under threat.
  • Most are losing at least half of their soil organic carbon (SOC) stocks. 
• Goodness of black Soil:
  • The inherent fertility of the soils make them the food basket for many countries and are considered essential to the global food supply. 
• Reason for the changes: 
  • Land-use change, 
  • unsustainable management practices 
  • Excessive use of agrochemicals.

Black Soil

• Characteristics: 
  • These soils are characterised by a thick, dark-coloured soil horizon rich in organic matter. 
  • Most of the black soils suffered from moderate to severe erosion processes, as well as nutrient imbalances, acidification and biodiversity loss.  
  • Black soils are extremely fertile and can produce high agricultural yields thanks to their elevated moisture storage capacity. 
• India: 
  • Among the in situ soils of India, the black soils found in the lava-covered areas are the most conspicuous. 
  • Those soils are often referred to as regur but are popularly known as “black cotton soils,” since cotton has been the most common traditional crop in areas where they are found. 
  • Black soils are derivatives of trap lava and are spread mostly across interior Gujarat, Maharashtra, Karnataka, and Madhya Pradesh on the Deccan lava plateau and the Malwa Plateau, where there is both moderate rainfall and underlying basaltic rock. 
  • Because of their high clay content, black soils develop wide cracks during the dry season, but their iron-rich granular structure makes them resistant to wind and water erosion. 
  • They are poor in humus yet highly moisture-retentive, thus responding well to irrigation. 
  • Those soils are also found on many peripheral tracts where the underlying basalt has been shifted from its original location by fluvial processes. 
• Global coverage: 
  • They constitute 5.6 percent of global soils and contain 8.2 percent of the world’s SOC stocks. 
  • Despite representing a small portion of the world’s soils, black soils were key for food security and the global economy. 
  • Globally in 2010, 66 percent of sunflower seeds, 51 percent of small millet, 42 percent of sugar beet, 30 percent of wheat and 26 percent of potatoes were harvested from black soils. 
• Most significant trait: 
  • Its SOC Stocks which is approximately 56 billion tonnes of carbon.
  • This signifies their importance for climate change mitigation and adaptation. 
  • The ability of the soils to remove carbon from the atmosphere and lock it up in soil organic matter (called carbon sequestration) has been proposed as an important solution to mitigate human-induced climate change. 
  • Black soils have the potential to provide 10 percent of the total SOC sequestration globally if they receive proper attention. 
  • Europe and Eurasia have the highest potential at over 65 percent and Latin America and the Caribbean at around 10 percent. 
• Reason of concern: 
  • They are quickly losing their SOC stocks. They have lost 20 to 50 percent of their original SOC stock, with the carbon being released into the atmosphere mostly as carbon dioxide, exacerbating global warming.
• Cropland distribution: 
  • The distribution of black soil areas used as croplands varied in each region. 
  • Europe and Eurasia accounted for 70 percent of the soil in the total cropland, while North America, Latin America and the Caribbean and Asia had 10 percent each. 

Suggestions

• Preserving natural vegetation on black soils such as grasslands, forests and wetlands 
• Adopting sustainable soil management approaches on cropped black soils.
• To reduce the impact of tillage and seeding systems on soil health, the frequency (number of passes across the field that results in a soil disturbance) and intensity (mass of soil disturbed in a single pass) must be reduced.
• Cover crops can be a good practice for sustainable black soil management and needs to be adapted to the farming system, black soil types and climate. 
• Double cropping, the production of a second crop after the first crop has been harvested, provides an opportunity to utilize lateseason moisture and heat resources after the harvest of the cash crop. 
  • Early maturing crops, including annual forages or winter cereals can provide a window of opportunity for double cropping with cover crops 
• Maintaining a low quantity but high frequency of mulch might efficiently boost soil health without compromising crop yields and as well optimize the use of stover.

Source: DTE