The soil is the living layer that covers the Planet Earth and on which a diversity of interactions take place, on which life itself depends.
More formally, the soil can be defined as a natural system, developed from a mixture of minerals and organic remains, under the action of the climate and the biological environment capable of supporting plant life.
It differs in horizons and supplies all or part of the nutrients and support that plants need by containing appropriate amounts of organic matter, air and water.
With the arrival of the Green Revolution and the industrialization of agriculture, the soil began to be seen in a fragmented way, ceasing to be considered as a living organism. With this aim, agricultural practices focused only on working on the physical and chemical aspects of the soil, ignoring the fundamental role of the multiplicity of micro-organisms that work for the manufacture of organic matter, the primary food of crops.
The practices of industrial agriculture and their consequences
Thetillageis the set of operations performed to prepare a bed ofsowing, for a certain culture.
Thetillageproduces generally unfavorable modifications from the point of view of the conservation of some properties of thefloors:
- Comprehensive degradation of the soil resource (physical, chemical and biological properties).
- Increased water and wind erosion of agricultural surfaces.
- Decrease in soil microorganisms.
- Gradual loss of productivity of the soils.
Plows invert the loaves of earth on which they work, leaving the surface exposed to the deteriorating effects of high temperatures and rainfall. Anaerobic and aerobic microorganisms found in the different layers of the soil die when their environmental conditions change.
Then, the discs used to level the ground, break up the clods, remove the soil and destroy weeds, generate a high degree of erosion in the soils. In silty and clay soils its action causes the formation of hard crusts and compaction.
Compaction caused by the weight of agricultural machinery also alters the structure of the soil. It reduces the pore space by altering the dynamics of water movement, aeration, root development and damages the habitat of various microorganisms.
With the aim of increasing productivity and mass dosing the amounts of nutrients necessary for the development of the crop, synthetic nutrients such as nitrogen, phosphorus and potassium, among others, are applied through irrigation water or in granulated form.
Synthetic fertilizers are very soluble in the soil because they are presented in the form of salts; plants can then assimilate them quickly by the roots and without any effort, but they cannot make a selection of nutrients when fertilized constantly and intensively.
This situation of constant fertilization produces "accustoming" in the plants and the activity in the soil is impoverished, because the conditions for the manufacture of organic matter are not propitious.
Chemical fertilizers also cause changes in the structure of the soil, increase its salinity and alter its pH.
Excess salts affect nutrient assimilation by plants and soil microbial activity.
Altering the pH of the soil will alter the availability of some nutrients, affect the presence of microorganisms and the formation of organic matter.
If fertilizers increase the acidity of the soil, the population of microorganisms will decrease. On the contrary, other chemical fertilizers, such as nitrogenous ones, cause an increase in the population of microorganisms that is detrimental to crops.
Many times, excess fertilizers penetrate the groundwater layers, polluting them. They can also reach watercourses and mirrors, generating environmental problems such as eutrophication.
Application of insecticides, fungicides and herbicides
The application of agrochemicals negatively affects the biodiversity of the soil.
Contamination by agrochemicals is produced mainly by direct applications in agricultural crops, but also by bad practices such as inadequate washing of container tanks, leaks in storage tanks and residues discharged and disposed of on the ground, accidental spills, etc.
In this way, agrochemicals are dispersed in the environment and become pollutants for animals and plants mainly and for soil, air and water, threatening their balance and representing a danger to public health.
The degree of leaching (the movement of substances through the phases of the soil) depends on the solubility of the compound in water, its chemical nature and the pH value of the soil, which is favored by its adsorption capacity, this varies mainly by the percentage of clays, sands and silts present in it, by high temperatures and by rainfall.
The most persistent agrochemicals in soils can contaminate the following crops and even enter the food chain, such as herbicides that have been detected in the fat of cattle and even in breast milk.
The search for short-term productivity over ecological sustainability, practiced in recent decades, has left a global balance of pollution and poisoning where the so-called Green Revolution to shovel world hunger has been a worse remedy than disease.
On the web beforetodoestoeracampo.net you can find references on soil improvement and conservation.