What is Chernozem Soil?
Chernozem is a type of soil that is black in colour and is rich in nutrients. The chernozem soil is rich in humus ranging between 4% to 16% along with a higher concentration of nutrients like phosphoric acids, phosphorus and ammonia. This makes the chernozem soil very fertile and hence one of the most useful soils for agriculture and results in high agricultural yields.
Also, chernozem has high moisture storage capacities. It is also included as a Reference Soil Group of the World Reference Base for Soil Resources. It is one of the 30 soil groups which are classified by the Food and Agriculture Organization (FAO).
History and Formation of Chernozem Soil
Chernozem is a humus-rich grassland soil that is used extensively for agricultural purposes like growing cereals and for the raising of livestock all over the world. The word itself comes from the Russian language which means black earth. From the 19th and 20th century there have been discussions on the process of soil formation of Chernozem. They originated from the discussions on the climatic conditions of the early Holocene to roughly 5500 BC.
However, there has been no single consensus on any paleoclimate reconstruction that was able to accurately explain the processes of geochemical variations that had been found in Chernozems throughout central Europe. Better explanations were offered by the theory involving the anthropomorphic origin of the Chernozem soil formation.
The Chernozem soil is also known to have the highest magnetic susceptibility as well. This high magnetic susceptibility of Chernozem is explained by the process of vegetation burning by humans. The reasoning is that the initially deposited soil containing significant concentrations of goethite and ferrihydrite was converted to maghemite because of the exposure to temperatures of around 220℃ which are only reached because of the vegetation burning. These events of vegetation burning are a rare occurrence when only left to natural processes. Hence, most of the vegetation burning would have been carried out by the humans leading to the formation of a chernozem soil profile.
The chernozem soil profile is also obtained when there is an accumulation of black carbon. This is observed in some regions such as the regions spanning from North America to Lower Saxony. This accumulation of black carbon is thought to partially originate from some charred materials. Because of these wide variations in the chernozem soil profile, the term summarizes the different types of black soils that have the same appearance but the processes of different formation histories. An image of the chernozem soil is shown below:
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Distribution of Chernozem Soil
To answer the question, chernozem soil is found in which region, we must understand the distribution of the soil geographically. They are distributed in the middle latitudes of both hemispheres especially in zones commonly known as prairie found in Argentina, pampa found in Afghanistan, and the steppes in Asia or eastern Europe. Also, it was originally found by the Russian geologist Vasily Dokuchaev in 1883, in the region of the tall grass steppe or the prairie of Eastern Russia. In total, they are present in almost 1.8% land area of the total continental landmass which is approximately 230 million hectares of land.
There are two concentrated belts in the world that show that the chernozem soil is found in which region. One of the belts is the Eurasian belt and the other one is the one along the Canadian Prairies. The Eurasian belt extends from eastern Croatia along the Danube river, from southern and eastern Romania to northeast Ukraine across the Central Black Earth Region of central Russia and southern Russia to Siberia. The Canadian Prairies belt in Manitoba passes through the Great Plains of the United States reaching as far as south of Kansas. Other places where similar such soil types are found are Texas and Hungary. The map given below shows that the chernozem soil is found in which region.
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The layer of the chernozem soil ranges from a few centimetres to a few metres. In Ukraine, a 1.5-metre layer of the chernozem is found. Similar thick layers of chernozem soil profile are found in the Red River Valley region in the northern US and Canada. In small quantities, chernozem is also found in Poland, Northwest China, near Harbin. In Australia as well, the soil is found around the region Nimmitabel which is some of the richest soils in the nation.
Primarily there are two classification systems of the chernozem soil that are the Canadian Soil Classification and United States Soil Classification. They are classified as chernozemic, brown chernozem, dark brown chernozem, black chernozem, and dark grey chernozem.
FAQs on Chernozem Soil
1. What exactly is Chernozem soil?
Chernozem soil, which translates to "black earth" in Russian, is a type of soil renowned for its exceptional fertility. It is characterised by its deep, dark-coloured top layer, which is extremely rich in humus (decomposed organic matter). This soil contains high percentages of vital nutrients like phosphoric acids, phosphorus, and ammonia, making it one of the most productive soils in the world for agriculture.
2. What are the main characteristics of Chernozem soil?
Chernozem soil has several distinct characteristics that contribute to its fertility:
- High Humus Content: The topsoil typically contains 5% to 15% humus, giving it a black or dark brown colour.
- Granular Structure: It has a well-aggregated, crumbly structure that allows for good aeration and water penetration.
- Rich in Nutrients: The soil is abundant in essential plant nutrients, particularly nitrogen, phosphorus, and calcium.
- Neutral pH: The surface layer usually has a neutral to slightly alkaline pH (around 6.5 to 7.5), which is ideal for nutrient availability.
- Good Moisture Retention: Its high organic matter content helps it retain moisture effectively, supporting crops during drier periods.
3. How is Chernozem soil formed?
Chernozem soil forms over long periods under specific climatic and environmental conditions. The process typically involves the accumulation of a thick layer of organic matter from the decomposition of deep-rooted grasses in temperate, semi-arid climates like steppes or prairies. The relatively low rainfall prevents essential nutrients from being leached away, while the activity of soil organisms like earthworms mixes the humus with mineral particles, creating the deep, dark, and fertile topsoil.
4. Where in the world is Chernozem soil typically found?
Chernozem soils are predominantly found in the middle latitudes of both hemispheres. These regions include the vast Eurasian steppe, stretching from eastern Europe and Russia into Siberia, with Ukraine being particularly famous for its extensive Chernozem belt. In North America, they are found in the prairies of Canada and the United States, and in South America, they are located in the pampas of Argentina.
5. Is Chernozem soil found in India?
While true Chernozem soil is not found in India, the country has a very similar and equally fertile soil known as Black Soil or Regur Soil. These soils are often called Tropical Chernozems. They are primarily found across the Deccan Plateau, covering large parts of states like Maharashtra, Madhya Pradesh, Gujarat, Karnataka, Andhra Pradesh, and Tamil Nadu.
6. Why is Chernozem soil so exceptionally fertile and ideal for farming?
The exceptional fertility of Chernozem soil is due to a combination of factors. The high concentration of humus acts as a slow-release reservoir of nutrients for plants and improves the soil's structure and water-holding capacity. The presence of calcium carbonate helps bind soil particles into stable aggregates, which promotes good drainage and aeration for plant roots while resisting erosion. This unique combination makes it highly productive with minimal need for fertilisers.
7. How does Indian Black Soil (Regur) differ from true Chernozem?
The main difference between Indian Black Soil and true Chernozem lies in their parent material and formation. True Chernozems are formed on loess (wind-deposited silt) in temperate grasslands. In contrast, Indian Black Soils are derived from the weathering of volcanic basalt rock of the Deccan Traps. This gives them a higher clay content, leading to their characteristic swelling when wet and shrinking when dry, a property known as self-ploughing.
8. What types of crops are best suited for cultivation in Chernozem soil?
Thanks to its high fertility, Chernozem soil is ideal for growing a wide variety of crops, especially grains. The most common crops cultivated are cereals like wheat, barley, and maize. It is also excellent for oilseeds such as sunflowers and rapeseed. In India, the equivalent Black Soil is famously suited for growing cotton, which is why it is often referred to as 'black cotton soil', along with sugarcane, jowar, and tobacco.
9. What are the primary threats to Chernozem soil today?
Despite its resilience, Chernozem soil faces several threats from human activities. The main dangers include:
- Soil Erosion: The fine texture of the soil makes it vulnerable to erosion by wind and water, especially when vegetation is removed.
- Loss of Organic Matter: Intensive agricultural practices without proper management can deplete the soil's rich humus content over time.
- Compaction: The use of heavy farm machinery can compact the soil, reducing aeration and water infiltration.
- Salinization: Improper irrigation can lead to the build-up of salts in the soil, reducing its fertility.
