PROTECTION OF THE SOIL AGAINST TWO PHYSICAL PHENOMENA THAT REDUCE ITS STRUCTURAL QUALITY
Today we delve a little into two phenomena that can and do occur at ground level, greatly modifying their physical structure and the consequence of which is disastrous for crops, especially in the early stages of development. We talk about sealing, crusting and actions for the protection of the soil of our organic garden .
IS IT THE SAME SEALING AS CRUSTING?
Many times they are used interchangeably to designate a compaction of the most superficial parts of the cultivation soil but they are not exactly the same . The processes that form them and the state of the soil in each of them is different but they can be closely related . The main and most important difference is that the state of the soil in each of the two is completely different. Sealing occurs with a moist soil and crusting the state of the soil is dry. Let’s go one by one.
WHAT IS SOIL SEALING?
Soil sealing is a thin compact layer a few millimeters thick, which forms due to the kinetic force of rain or irrigation drops falling on the surface. Let’s go into a little more detail.
Effect of the raindrop hitting the soil surface
On bare soil, without vegetation, the drops of water, whether from rain or sprinkler irrigation, contain a kinetic force that, when falling on the surface, breaks up and breaks up the aggregates of the soil * in the superficial part.
This situation occurs after sowing, in the early stages of plant development where the plant cover is not very thick or in recently tilled soils.
In these three cases, the proportion of bare soil with respect to the vegetation cover is highly unbalanced and the drops of water hit the soil fraction irremediably.
This energy that breaks the aggregates of the soil, causes a dispersion of fine particles that will be mobilized by the surface of the soil and will fill the pores, thus achieving the so-called sealing effect.
This happens on a millimeter scale or even smaller, but in the end, the result is the following:
- The apparent density of the soil increases, as the pores are filled with the particles resulting from the disaggregation. It makes a heavier soil.
- Decreases porosity .
- Difficulty of infiltration of water into the soil due to this sealing and there are puddles or runoff in the case of sloping land.
- If the soil dries, we will give way to the crusting phase.
As we have discussed before, unlike sealing, surface crust occurs in dry soil.
It is related to sealing, since if this phenomenon occurs and subsequently, the moisture contained in the soil disappears, this crust is produced, which has a series of characteristics that prevent the proper growth of our crops:
- It is very hard in consistency . The soil will be very compacted so the roots in the nascence phases the plant has many difficulties to emerge the vegetative part due to the impossibility of breaking the crust.
- It is very little permeable to water and air, producing easy waterlogging without water infiltration in the most internal phases of the soil.
- If the scab forms at the base of the plant (if it has managed to emerge) it can cause stragulation and therefore the plant will die.
WHAT CAN WE DO IN THE FACE OF THESE PHENOMENA?
We have already talked about various techniques that favor the soil structure to avoid these compactions, but let’s make a compilation of techniques for soil protection:
- One of the reasons for these phenomena is due to the instability of the soil aggregates. Organic matter, a humified soil, favors the stability of these aggregates, therefore, maintaining a soil nourished with compost , mulch or manure is essential to make a structurally stable soil.
- Leave bare ground as little (reasonably) as possible. The planting of green manures is a solution that enriches the soil in organic matter and we favor the protection of the soil with the vegetal cover of the species that we plant as green manure while they are developing.
- The techniques mulching are one of the better ways to prevent fraying of the soil and therefore the phenomena of sealing and crusting by providing protection of the soil modélica to these phenomena.
Straw mulch for soil protection
- The tillage is necessary but an excess, can be counterproductive, therefore, make the tillage strictly necessary.
- Avoid the labor sole, not stepping on the cultivated land or doing it as little as possible (either in the orchard with your feet, or in farms with the pass of machinery)
- With drip irrigation or drip irrigation, the kinetic energy of the drop is almost zero compared to sprinkling (the drop does not hit the ground).
* NOTE: Soil aggregates : Cohesion and adhesion of soil particles (sands, silts, clays, organic matter …) with different degrees of structural stability. The stronger the bond, the better structure the soil will have and therefore, the greater porosity and permeability, allowing better exchange and mobilization of the air and water phases. If you want to know more about the structure and aggregation of the soil, we leave you this link from the FAO where the phenomena and the different forms of structural soil aggregation are explained.
One sentence for the end: The protection of the soil, as well as the continuous improvement of its physical, chemical and biological properties is something that we must never neglect if we want a model organic garden