Black soils are characterized by a dark, thick soil horizon that is rich in organic matter. These soils are found in various regions across the globe, including Russia, Kazakhstan, China, Argentina, Mongolia, and Ukraine. Known for their high agricultural yield capacity due to elevated moisture storage, black soils are extremely fertile. They contain substantial amounts of iron, lime, calcium, potassium, aluminum, and magnesium but are deficient in nitrogen and phosphorus. Accounting for 5.6% of global soils, they hold approximately 56 billion tons of carbon, or 8.2% of the world’s SOC (Soil Organic Carbon) stocks.
Soil organic carbon, a measurable component of soil organic matter that makes up 2-10% of most soil’s mass, plays an integral part in the physical, chemical, and biological function of agricultural soils. As such, black soils, with their inherent fertility, serve as the food basket for many nations and are essential to the global food supply. Moreover, they have a particularly pivotal role in climate change mitigation and adaptation.
World Soil Day and Its Importance
The International Union of Soil Sciences (IUSS) recommended World Soil Day (WSD) in 2002. The Food and Agriculture Organization (FAO) subsequently supported the formal establishment of WSD as a global awareness-raising platform under the leadership of the Kingdom of Thailand within the framework of the Global Soil Partnership. Recognized by the UN General Assembly (UNGA), the first official WSD was held on 5th December 2014. This date corresponds with the official birthday of H.M. King Bhumibol Adulyadej, the King of Thailand, who officially sanctioned the event.
The main objective of WSD is to heighten public awareness about significant environmental issues arising from soil degradation, such as erosion, loss of organic matter, and decreased soil fertility. The theme for World Soil Day 2022 is “Soils, where food begins.”
Current State of Black Soils
Despite their critical role in food security and the global economy, black soils are rapidly losing their SOC stocks. They have lost 20 to 50% of their original SOC stock, with the carbon being released into the atmosphere primarily as carbon dioxide, which contributes significantly to global warming. Factors responsible for these losses include unsustainable management practices, land-use change, and excessive use of agrochemicals. Furthermore, a large number of black soils are experiencing moderate to severe erosion, nutrient imbalances, acidification, and biodiversity loss.
Impact on Smallholder Farmers and Food Security
Smallholder farmers, especially those from vulnerable countries across Africa, Latin America, and Asia, are particularly affected by the deteriorating health of black soils. Most lack access to organic and inorganic fertilizers and are currently navigating a 300% increase in fertilizer prices. As a result, the reduced availability and soaring cost of fertilizers are driving up food prices and exacerbating food insecurity.
Initiatives to Improve Soil Health
To mitigate these issues, several initiatives have been launched. These include the Soil Health Card Scheme, Organic Farming, Paramparagat Krishi Vikas Yojana, Fertilizer Self-Sufficiency, Digital Agriculture, Carbon Farming, and the Nutrient Based Subsidy (NBS) Scheme. Through these initiatives, the preservation of natural vegetation on black soils such as grasslands, forests, and wetlands, and the adoption of sustainable soil management practices on farmed black soils is encouraged. This collaborative effort aims to produce safe, nutritious, and micronutrient-rich food in a sustainable manner that prevents soil degradation, reduces greenhouse gas emissions, and decreases agrifood systems pollution.
Understanding the Formation of Black Soil
Black soil, also known as regur soil or black cotton soil, is ideal for cotton cultivation. The formation of black soil is largely influenced by climatic conditions and parent rock material. Black soil is typical of the Deccan trap (Basalt) region, which extends over the northwest Deccan plateau and consists of lava flows (fissure volcanic rock). This plateau includes parts of Maharashtra, Madhya Pradesh, Gujarat, Andhra Pradesh, and some parts of Tamil Nadu. Though rich in lime, iron, magnesia, and alumina, these soils lack phosphorus, nitrogen, and organic matter. Hence, understanding the formation and characteristics of black soils is crucial for their conservation and sustainable use.