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The importance of soil

Soil is composed of rocks, minerals, water, air, and organic matter. The presence of the latter humushumushumus is crucial as it allows most plants to grow and, as a result, entire ecosystems connected with them, such as forests, arable land, or meadows.

The soil formation process is time- consuming. It starts with the weathering of rocks. Thanks to the presence of water, conditions are ensured in the rock mantle for the least demanding organisms, such as bacteria, algae and lichens, to grow. Their remains subject to decomposition enable the growth of more complicated organisms. This way the rock mantle is enriched with organic matter, transforming into soil.

In natural conditions, the matter circulates and the substances obtained from the soil by plants sooner or later return to it (food chain!), thus the situation is stable. Everything changes when we start to engage in wasteful exploitation of soil for farming purposes – we use the soil’s resources but when harvesting crops, we fail to give back the minerals taken by plants. If this lasts for too long (depending on soil fertility, sometimes a few years is enough), the soil loses its productivity. This is referred to as soil degradationsoil degradationsoil degradation

Main causes of soil degradation

There are many causes of soil degradation and they often overlap.

The most common one is overgrazing – the animals eat plants so quickly that they fail to grow again. As a result, soil is uncovered, mainly its humus level. Wind and rainwater easily remove it, which makes the soil lose its properties quickly. It is particularly characteristic for dry land and semi‑dry land, especially in the Sahel, Africa. Similar effects are caused by wasteful deforestation, but the consequences are visible much faster.

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Na ilustracji diagram kołowy. Przyczyny degradacji gleb na świecie. Trzydzieści pięć procent nadmierny wypas, trzydzieści procent – wylesianie, dwadzieścia siedem procent – działalność rolna, siedem procent – nadmierne wykorzystanie roślin, na przykład jako opał, jeden procent – działalność przemysłowa.

Farming, if improperly conducted, also contributes to soil degradation. Long‑term, irrational exploitation leads to the reduction of humus content. This results in reduced amount of nutrients in the soil, but also deterioration of soil structure, limited ability to retain water, reduced activity of soil organisms, and impaired chemical stability.

The most obvious solution is to use fertilisers. The best ones are the natural ones, but usually there is too little of them. If fertilisers are improperly used, they may be counterproductive. For example, with too high doses, the soil may become contaminated – the soil microorganisms die, heavy metals are activated, and pH changes (acidity rises), which impacts the ability of plants to intake nutrients. Overfertilisation is typical for highly developed countries with intensive farming.

Consequences of soil degradation

The extent of soil degradation varies. For every continent, though, it means reducing the ability to deliver agricultural produce. The problem, however, is not of the same importance everywhere.

In Europe, population growth is very slow and a lot of agricultural produce is imported. In addition, in highly developed countries of Europe, North America or Asia, productivity is rising and agricultural production on non‑degraded soil is growing. In Africa, on the other hand, especially in its Sub‑Saharan part, the situation is completely different – population rises very fast and poor economic growth limits the ability, or even makes it impossible, to import food.

Keywords

soil degradation, overfertilisation, soil fertility, humus, soil formation process

Glossary