Soil Degradation

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

Read the previous part. ← The cycle of nutrients and the mechanical composition of the soil

How does the soil live and why is it degrading. Part 3

If a vegetable grower violates the laws of agriculture, does not provide a positive balance of elements in the soil, then in this case its fertility sharply decreases, processes of degradation (dying) take place in it.

Soil degradation is of a global (world) nature, it is natural (by territories) and accidental - it occurs most often through the fault of the owner of the soil.

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Global degradation

Global soil degradation occurs all over the world, air and water areas are polluted as a result of man-made disasters, accidental emissions and weapon tests. In the popular literature, the concept of contamination with "heavy metals", radionuclides, and artificial radioactive elements is increasingly used.

Associated with them is the idea of something toxic, dangerous to human health, as well as to animals and plants. These terms are borrowed from technical literature, where metals are divided into light and heavy. For biological classification, it is more correct to be guided not by the density, the weight of the metal, but by the atomic mass and refer to the heavy metals with a relative atomic mass of more than 40.

The concept of the toxicity of all heavy metals is a clear delusion, since this group includes copper, zinc, molybdenum, cobalt, manganese, iron, i.e. those elements, the great positive biological significance of which has long been discovered and proven. Some of them are used in agriculture as trace elements. It is fair to use the term " heavy metals " when talking about metals that are dangerous for living organisms, for which only one negative concept has been fixed - "heavy" in the sense of toxic.

This group includes mercury, cadmium, arsenic, lead and radioactive elements. By all accounts, they are the most likely and hazardous soil contaminants, as these metals are widely used in industry, transportation and military purposes. Motor vehicles also contribute to global soil pollution.

Natural degradation

The soil-plant complex produces the most valuable and necessary biological products for humans (food, raw materials), accumulates and distributes solar energy as a result of plant photosynthesis, provides an optimal balance of oxygen, carbon and nitrogen in the atmosphere of the garden plot and is a screen that keeps the most important chemical elements from runoff and pollution to groundwater.

In addition, with natural degradation, the arable soil horizon is exposed to various negative influences: it becomes overgrown with weeds, turns into a breeding ground for pests and plant diseases, becomes contaminated with various chemicals, human waste products, solid, liquid and gaseous waste, organic animal waste, municipal wastewater, combustion products fuel, etc.

Natural soil degradation also includes the removal of nutrients from the soil by plants and their alienation from the soil with the harvest of plants, losses from the vegetable plot of the dacha, the harvest is taken to the city. The loss of nutrients with the harvest from the soil in this case reaches up to 30-50%. In addition, the soil loses its physical properties, becomes compacted, trampled, destroyed during construction work. The climate of our zone is such that part of the nutrients is washed out annually due to excess rainfall. Leaching accounts for 10-15% of all soil reserves. The soil degrades and, if it is simply not used for agricultural purposes, turns into a fallow. Useful microorganisms die in it, washout processes are much stronger than in arable land, etc.

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Accidental degradation

In addition to natural soil degradation, there is a loss of soil fertility associated with irrational, primitive use of farming systems, and global anthropogenic impact on the biosphere. Academician V. I. Vernadsky, examining the soil, wrote: "The face of the planet - the biosphere - chemically changes sharply by a person consciously and, mainly, unconsciously …". Agrarian craft really requires good knowledge and ability to manage soil fertility, you need to be able to manage the cycle of substances and achieve a positive balance of nutrients in the soil.

In horticultural farms, soil degradation is much faster than in industrial agriculture. Vegetable growers are often guided not by knowledge, but by their preferences, pleasures, and forget about the soil, that it needs to be fertilized, processed, preserved (this does not mean that nothing should be done). Some gardeners are eliminated from the fight against weeds, pests and plant diseases, primitively cultivate plots, do not follow the agricultural techniques of plant cultivation.

They refuse to apply fertilizers or apply them little, irregularly, sometimes they use random fertilizers, apply them unevenly, in spots, they do not use a crop rotation system. The beds and paths on the plots remain in the same place for several years, which leads to prolonged compaction. They forget or don't know about scientific farming systems. And as a result, the diversity of the soil is formed in terms of fertility, it loses all its positive properties, degrades and dies.

Accidental degradation processes such as soil compaction, non-observance of proper agricultural practices, soil cultivation, irregular irrigation, construction work, surface tillage lead to a decrease in the intensity of soil respiration. The supply of oxygen to the depths of the soil decreases, which causes the appearance of acidic reactions, the accumulation of compounds toxic to plants, and a decrease in the number of useful biota.

As a result, microbiological processes (ammonification, nitrification, etc.) die out and negative processes begin to prevail (denitrification and others, which lead to a loss of nitrogen up to 30% or more). And we get a decline in the quality of the crop and inadequate food products. Human activities are not always beneficial to the soil. The unevenness of the relief, the heterogeneity of the soil and the plant habitat are also considered negative and lead to soil degradation.

How to avoid degradation

In total, the loss of nutrients, a decrease in effective soil fertility during the year can reach 70%, which means that the lack of harvest, the yield of low-quality and toxic products in the country can also reach high levels.

The gardener himself does not notice this, because it is not felt instantly, now, but then everything negatively affects both the soil and the health of the gardener. Love for the environment, the gardener's addiction to a certain farming system cannot correct mistakes, on the contrary, they can cause degradation. To really improve the soil, it is necessary to carry out systematic correction on the site.

The types and rules of correction are as follows:

• adherence to planting schemes and agricultural techniques for plant cultivation, preserving the best agronomic soil structure, improving soil respiration, reducing the intensity of acidic processes and the accumulation of toxic products for plants, the necessary control of weeds, diseases and plant pests;
• joint application of organic and mineral fertilizers to the soil in the proportion necessary for a particular crop;
• claying or sanding of soils for long-term construction of the root layer of the soil;
• application of scientifically grounded crop rotations taking into account the allelopathic impact of agricultural crops on each other.

We wish you success!

Gennady Vasyaev, Associate Professor, Ch. specialist of the North-West Regional Scientific Center of the Russian Agricultural Academy

Olga Vasyaeva, amateur gardener

How the soil lives and why it degrades:

Part 1. The structure of the soil: five main layers

Part 2. The cycle of nutrients and the mechanical composition of the soil

Part 3. Soil degradation