The black gold of Ukraine and the most fertile soils in the world

Ukraine is pivotal in feeding the world and producing grains, thanks to its remarkably fertile black Chernozem soils. This "good black earth" is among the most productive soils in the world, a fact Russians are well aware of. Russia has a long tradition of soil science, and its experts have made significant contributions to the field. So for soil scientists, Russia's unhealthy interest in Ukraine is not surprising. We explain what Chernozems are, where in the world they can be found, and we explore some parallel situations - and disasters - in the Americas.

Author: Kathelijne Bonne 

Chernozems, the black soils of Ukraine

Chernozem is the name of the soil type occurring in Ukraine, according to the World Reference Base of Soil Resources (WRB), the soil classification system of the Food and Agriculture Organization of the United Nations (FAO). Chernozems have a thick black upper layer, the "chernic horizon" that is rich in decomposed plant material and therefore contains a lot of humus and carbon. In Ukraine, the thickness of the chernic horizon can be up to several meters!

The importance of humus and nutrients

Humus consists of humic acids (complex organic molecules) that are formed after decomposition of plants and digested by soil life. Thanks to the chemical structure of these humic acids, humus does not only retain water, but also nutrients, such as calcium, magnesium, potassium, ammonia, phosphorus, sulfur, iron, manganese, zinc, copper, etc. In contrast, in humus-poor soils, rain or irrigation water and the dissolved nutrients, simply sink to deeper layters, beyond the reach of plant roots. Humus-rich soils can bridge a dry season because of these properties.

Chernozems also has a very spongy, airy structure: plant roots have no trouble branching out into the soil and there is enough oxygen so that soil organisms can breathe and interact. Many earthworms contribute to the good soil structure and the good qualities of the soil. Biodiversity and abundancy of organisms is high in Chernozems, and they are active at greater depths than in other soils. The soil also contains a lot of calcium, so it does not easily become acidic. 

All of these properties mean that a Chernozem does not need much additional fertilizers or soil conditioners and produces good yields, provided it is managed sustainably.

• Read about fertilizers: The Nitrogen cycle: a story of food, war and bacteria.

Russian father of soil science

The name Chernozem (from chorniy, black and zemlya, land, earth, in Russian) was coined in 1883 by the Russian geographer Vasily. V. Dokuchaev, the founder of soil science. He recognized that agricultural productivity was largely determined by the type of soil, and that this in turn was influenced by geology, relief, climate, organisms, and the passing of time. The name Chernozem was adopted from the Russian classification when the FAO created the WRB, the globally applicable classification, in the 1980s and 1990s (*). Several Russian names are now fully established in soil science circles.

The Americans did not adopt the Russian nomenclature, and developed their own method: the Soil Taxonomy of the US Department of Agriculture (USDA). This system, too, is applicable worldwide and was drawn up after the agricultural disaster of the Dust Bowl in the 1930s. In the Soil Taxonomy, Chernozems correspond to the category of Mollisols after mollis, soft, and sol, soil, in Latin.

(*) Many countries have their own local system of classifying soils. This is useful for local food production. For example, for Icelandic farmers it is not very relevant to know how one deals with farming problems in the Tropics. Globally applicable classifications are especially useful for knowledge exchange, policy making, and to provide food security in a globalized world. Soil classification are also continuously updated, based on new knowledge and needs. Note as well that both Mollisols and Chernozems can still be divided into many subclasses, they are anything but homogeneous.

Soils of the steppes, prairies and pampas

One-fourth of the world's Chernozems are located in Ukraine, and the country itself consists of 68% of this type of soil. Beyond Ukraine chernozems extend across two major black-earth belts in the world: in the steppes of Eurasia, and in the prairies of the Great Plains in North America. They are typical of grasslands in continental climate belts with cold winters, rainy springs and hot summers. Similar soils, with slightly different characteristics (Mollisols), stretch over vast regions in the Argentinean pampas.

Regenerative agriculture of Ukraine

To date, Ukraine is one of the three largest grain exporters, and a world leader for soy, maize and sunflower oil. The blue-yellow flag is reminiscent of the vast golden-yellow grain fields under a radiant blue sky. In addition to the EU and surrounding countries, the Arabian Peninsula is an important market. Ukraine also began to establish itself as an important country for the export to the EU of organic crops. The UN also identified Ukraine's potential in regenerative agriculture, a sustainable form of agriculture that does not harm the environment and increases biodiversity. They also looked at the potential to capture carbon from the atmosphere, and sequester it in Ukrainian soils.

Soil degradation in Ukraine 

But this vast soil wealth is just too good to be true. Ukrainians are people like me and you who, like our fellow humans elsewhere in the world, inflict great damage to the environment. In theory, Chernozems can feed the world, but in practice they are subject to predatory agriculture and soil degradation and erosion. It is estimated (in this FAO report) that Ukraine loses 500 million tons of soil per year through erosion, equating to a loss of $5 billion per year in nutrients. Or in another calculation, per ton of grain produced, 10 tonnes of soil are lost. The same FAO report offers solutions and methods for conservation agriculture (CA) and climate-smart agriculture (CSA), which have already been successfully applied in Kazakhstan and elsewhere.

Gone with the wind: soils blown away

Despite their good reputation, we can completely lose the best soils in the world. The Dust Bowl may not ring a bell with most people today, yet it was a disaster of epic proportions in the 1930s in the Great Plains of the United States and Canada, where fertile black Mollisols occur. Deforestation, plowing, and prolonged drought in this American "breadbasket" resulted in tragic soil erosion. Strong winds blew away the top layer of soil that had been reduced to dust; dust clouds rose and darkened the sky even thousands of miles away. Hundreds of thousands of farmers left their fields and moved to California and Oregon to start new lives. John Steinbeck's Pulitzer Prize-winning book The Grapes of Wrath is about this event.

The New Black Gold

The world is at a tipping point, and the consequences of the war in Ukraine will ripple across societies worldwide. The soil problems will make it worse. Because phenomena such as the Dust Bowl, or other disasters, may occur again, and it would be a pity if this were to happen to the world's most fertile soils. Therefore, we need to remind ourselves what the basis of a stable, prosperous society is, and that is healthy food, clean water, clean air, and sustainable renewable resources, to which everyone has access. If these are in place, the energy transition can be accomplished peacefully. Therefore, sustainable management of forests, oceans and soils should be at the top of political agendas worldwide.

It seems that petroleum is no longer the black gold, the heyday of Big Oil is over, however well it has raised living standards to their current levels (at least in rich countries). Good black soils, like the Chernozems of Ukraine, are the black gold of the future (and in fact they always have been, it's just that soils never get the attention they deserve, and we are so far removed from nature that we are no longer aware of what we owe our prosperity to). Petroleum and gold cannot be eaten. Neither can money, as the Native Americans noted long ago. It is therefore of the utmost importance that soils are sustainably managed anywhere in the world.

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Important note: we talk in this article about fertile and productive soils in terms of human food production, hence adopting an antropocentric view. But also soils that do not produce crops for human consumption carry out important ecosystem services and are no less important for ecosystem health. 

Related articles: 

• The Dust Bowl comes to Spain: desertification and soil erosion. 
• The nitrogen cycle: a story of food, war and bacteria.
• Soil salinization: food security at risk.
• The planetary boundaries: is Earth safe for humans? 

Article written by Kathelijne Bonne, geologist and soil scientist. She also writes on Good Climate News. 

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