Chernozems of Ukraine: when bombs hit the soil
Ukraine's black soil has properties that made the country a global producer of commercial crops. Two-thirds of Ukraine consists of humus-rich Chernozems, the most fertile soils in the world. But fertile is not a synonym for resilient, unfortunately. And as war lashes the land, tanks roll over soils and clods of black earth fly around, many a soil scientist wonders: how great is the damage? What are the effects of bombs, tanks and ammunition on the soil? We look at what makes chernozems so productive but also vulnerable, using the work of an American military geographer.
Author: Kathelijne Bonne
Chernozem is the name of the famous black soils that occupy 60% of Ukraine's territory. This Russian name literally means black (cherny) soil (zemlya). This soil type owes its fertility to the incredibly thick spongy humus layer or O-horizon, which is tens of times thicker than usual. Humus is composed of carbon. For this reason, soils in which humus-forming processes occur are suitable candidates for climate mitigation via carbon capture and storage. Chernozem soils are also rich in nitrogen and phosphorus, hence require less fertilizer. Thanks to the rich soil life and spongy structure, there is abundant biological activity and exchange of nutrients and minerals. But why is Ukraine so well endowed in terms of soil wealth?
Steppe, climate, Ice Ages
Chernozem soils stretch from west to east in a belt, the black earth zone, through the steppes of Eastern Europe into Central Asia. Similar soils in the Americas are the black, humus-rich Mollisols of the prairies of North America and of the pampas in Argentina, where beef is produced in too great numbers. Despite their good qualities, chernozems and mollisols have certain weak points that have already caused tremendous losses in the Great Plains, see my first article on black soils and the Dust Bowl disaster.
It is no coincidence that fertile black soils are concentrated in specific places on the planet. Climate is responsible for that. The huge accumulation of humus is the result of the right balance between rain and drought. In steppe regions it rains just enough to sustain grasses but not lush forests. The little rain that falls keeps the humus from decomposing so it can accumulate.
Ukraine is well endowed by nature not only in terms of soil, but also in terms of geology. Deep below the chernozem soils are layers of loess sediment, deposited by wind during the last Ice Age. Loam consists of fine sand and clay, a mix that leads to favorable properties. Ukraine has thus inherited the best of two climates, the earlier Ice Age and the actual steppe climate.
South of Mariupol
Just south of war-struck Mariupol in the hard-hit Donbas region is a town named Dokuchaievsk. Its name is particularly relevant. It is named after the 19th century Russian geographer Vasily Dokuchaev. He is known as the father of soil science because he had noted in the Tsarist Empire that soil is a complex entity that develops under the influence not only of the parent rock, but also of climate, life, relief and time. His ideas are at the base of modern soil science. Even today, Russia remains a soil science authority, and it is one of not many countries to possess a museum dedicated entirely to soil: the V.R. Williams Museum of Soil and Agriculture in Moscow, active since 1954.
Are chernozem soils a target?
Knowing all this, is it a coincidence that Ukraine is in the eye of the storm? And we venture a step further: are the chernozem soils themselves the target of the war? Would Ukraine have been invaded had it only had the highly degraded, salt-affected soils at its disposal like those around the nearly dry Aral Sea? Perhaps we should ask politics experts how, in war strategy, the value of a black chernozem soil is weighed against Ukraine's other industries, such as coal and minerals in the Donbas. We cannot read the political agendas, but what is certain is that the war, whatever the outcome, will have far-reaching consequences simply because of the soil wealth. Perhaps one of the few benefits of the conflict is that we have sharpened our soil knowledge and that we must demand from our politicians to impose and enforce sustainable soil management, wherever we live.
Ukraine's agricultural output is suffering heavy losses this year due to the impact of the war, primarily because farmers, at least those who have not fled, are finding it more difficult to work the land. But there are also more direct consequences of war activities. The work of military geographer Joseph Hupy of Purdue University in Indiana State shows how soils absorb military conflict. During his career, Hupy examined sites of violent conflict in France and Vietnam. He described how war leaves its mark on the soil, e.g. through bombing, tanks and pollution.
Hupy coined the term "bomb turbation," a wry echo of the term bioturbation, which refers to the marks left by soil organisms in the subsurface, such as wormholes. The traces of impacting bombs are, of course, of another order of magnitude. They leave a crater similar to a small meteorite impact. When a bomb hits, soil material and rock beneath it gets intensely mixed and crushed, and becomes impermeable. Farmers can fill in those holes and plow over them, but the good structure of the soil and the cohesion of the soil aggregates are destroyed. The crushed, impermeable soil prevents water from seeping to depth. The soil becomes saturated with water, and therefore plant roots suffocate because they no longer get oxygen. Something similar occurs when heavy tanks, not unlike large harvesters, are driven over the soil. The soil collapses, it gets compacted, and the space for plant roots disappears.
Chernozems in particular are also especially susceptible to compaction because they are very airy and spongy. Compaction can reduce yields by up to 60 percent.
Soil fights back
But chernozems have a way of fighting back. They can hold a lot of water, which is why they act like a sponge. It's best to think twice before driving over a wet chernozem. More than one tank has trapped itself and has been swallowed by the soil, so to speak. But it's a double-edged sword, the soil itself obviously doesn't get any healthier.
Fortunately, there is also good news, the soil is capable of recovering after a few years thanks to the activity and moving about of microscopic life and small animals. Recovery will be faster if the land is managed sustainable, for example by leaving the land alone for a time and allowing natural vegetation to regrow.
A more serious and long-term problem is the extreme soil contamination associated with war. Ammunition and other military equipment contain many heavy metals, such as arsenic and lead, and toxic substances, radioactive or otherwise, that leak into the soil. And when mining and industrial zones are also affected, as in the Donbas, the risk of the release of harmful substances is very high. Most toxins remain in the soil for a very long time, they are hardly degradable, and pollute groundwater, rivers and drinking water. Remediation of contaminated soils is complex and expensive, and it seems unlikely that any country in the post-war period can deal with it.
However the war will turn out, and into whose hands the chernozems will fall, let's just hope that the traditional Russian knowledge will be used to protect and restore the soil wealth of the black earth belt as best as possible.
New black gold?
The message is clear, war must be avoided at all costs, not only to avoid human suffering but also the destruction of crucial natural resources on which humanity depends. Humus-rich black soils are the new black gold of the future. They rise from the ashes of the petroleum industry, the classic black gold, which for decades seemed to be the world's most important resource (though it can't even be eaten, how can it be more important than food?). But let's not forget that soils are much more than a substrate in which food grows to serve humanity. That view is anthropocentric and outdated. Soils are connected to all other ecosystems of the planet through the exchange and cycling of essential elements and play a crucial role in the proper functioning of the earth as a unique planet on which human life is possible.
Soils are one of the least talked about ecosystems, primarily because we do not have a good view of what is happening in them. It appears to be a static immobile substrate and has no cuteness factor like a panda bear, pangolin or baby elephant, and therefore we feel less inclined to "save" soil or to grant it a protected status, although soil scientists worldwide are more and more listened to; and the importance of sustainable soil management and regenerative agriculture has already penetrated the highest political spheres.
Only action is still pending in most countries.
- The black gold of Ukraine and the most fertile soils in the world (also about Dust Bowl).
- The Nitrogen cycle: a story of food, war and bacteria.
- Soil salinization: what to do about it?
- The Dust Bowl comes to Spain: desertification and soil erosion.
- Doñana, drought and the Queen of the marshes.
Rebecca Dzombak, 21 juni 2022, Science News, Russia's invasion could cause long-term harm to Ukraine's prized soil.
Parya Broomandi, Mert Guney , Jong Ryeol Kim and Ferhat Karaca, Parya Broomandi, Mert Guney, 2020, Soil Contamination in Areas Impacted by Military Activities: A Critical Review Sustainability, 12(21), 9002; https://doi.org/10.3390/su12219002
Hupy, Joseph P.1; Schaetzl, Randall J.2. Introducing "bombturbation", a singular type of soil disturbance and mixing. Soil Science: November 2006 - Volume 171 - Issue 11 - p 823-836 doi: 10.1097/01.ss.0000228053.08087.19
Kathelijne: As a nature lover and earth scientist I am intrigued by how life, air, rocks, soil, ocean and societies interact on geological and human timescales.
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