- Heavy rains do more harm than good, and will not always improve the water situation in the soil.
- Will the soil take up water from heavy rainfall?
Poor quality soil cannot absorb the right amount of water.
Not all soil absorbs water in the same way. We know this very well. Unfortunately, it also happens that the soil does not absorb as much water from rainfall as it would need. The situation is a bit like with an illness. If a person is sick, they need to replenish many fluids. But these often do not quench thirst, do not improve condition, and are immediately sweated out, literally evaporating from the skin. It is similar with soil. Often, this is related to its poor condition.
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Even if the soil is dry, which means it needs a lot of water, but is also in poor condition, it may not absorb water. When does this happen? Of course, in strongly compacted areas, where we are dealing with a plough sole. We are talking here about worn-out areas in the field. Sometimes we see water pools on paths, also on so-called crossways, where the level of soil compaction is usually the highest. There, water stays on the surface longer, because due to the degree of compaction, a kind of concrete is created inside and on the surface itself, which does not let water through. The water will evaporate over time, and of course it will partially soak in, but it will only be a certain percentage of rainfall per square metre. And what percentage will it be? It is impossible to determine, there are too many variables here. In extreme situations, it may be the case that 20 l of rain has fallen, and only 1-2 l are absorbed by the soil. In such a situation, water pools are created. Where the soil is too compacted, there is a strong plough sole, even 90%. water may not be collected.
Soil rich in humus absorbs water better
Poor water uptake is associated with, among other things, low levels of humus. It is also indirectly due to low organic fertilization (many fields have not seen natural fertilizers for years). Here, in addition to balanced fertilization, including, if possible, manure, catch crops are helpful.
What else helps the soil absorb rainwater better? Certainly a diversified crop structure. Monoculture does not help the soil to be healthy, nor does it improve water-air relations. In addition, it is important to sow plants with an extensive root system, which penetrate the soil, creating channels in it, which in turn will transport water (the previously mentioned catch crops can play this role). A similar task is fulfilled by earthworms, which, by digging underground corridors, facilitate the circulation of water in the soil.
Heavy rainfall is not collected in its entirety
Regardless of how well the soil absorbs water, in the case of heavy rainfall we must reckon with the fact that there is rather no chance that all the water will remain available to the soil. As a result of very high rainfall intensity, surface runoff will occur. This will be a situation similar to what sometimes happens in cities during downpours. The streets are flooded, although there is no question of any flood at all, only short-term flooding. The sewage system simply will not keep up with receiving a large amount of water in a short time. The same will happen in the field – the soil, even the most absorbent, is not able to absorb a large amount of rainfall on an ongoing basis.
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Heavy rains have crusted the soil, possible overseeding of rapeseed
Heavy rain itself contributes to soil degradation. Due to the fact that the intensity of rainfall is then very high (heavy rainfall is considered to be when the total rainfall is 40 mm / m2 within an hour), the force of the drops is exceptionally high, they hit the soil with significant energy, thus damaging the top layer of soil. Additionally, such rainfall crusts the soil. This is a particularly high risk at the stage of plant emergence (e.g. as is the case now with rapeseed in those places where it has already been sown). However, even if nothing has been sown in the field yet, and it remains without any cover, a crust will form. The problem is that air relations in the soil deteriorate at this time, and because the soil on the surface is strongly compacted, any subsequent, even light rainfall, poorly penetrates this layer, which resembles real concrete.
