Mesozoic - Period in which reptiles developed
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Soil erosion and conservation
The soil, together with water, is one of the most important natural resources available to man. It produces food and fibers, supports buildings and roads, helps convert sunlight into usable forms of energy and a series of important physical, chemical and biological processes take place in it, such as the cycle of organic matter. In its most modern conception, the soil is considered an integral and vital element of our environment and a fundamental entity of ecosystems.
Soil conservation is therefore essential for the survival of the human race also because soil is a hardly renewable resource. However, in many parts of the world the soil has been so damaged and misused that it is no longer able to produce what humans need. This fact is due to the rapid increase in land use as a result of the pressure of the population and of technology which has favored the grafting of erosion phenomena, i.e. the physical loss (detachment and transfer) of the most superficial layers (horizons) of the soil. , that is of its most vital part, responsible for a high plant production. Once these layers are lost, it sometimes takes hundreds of years for them to reform by pedogenesis, that is to say that these physical, chemical and biological processes that lead to the reformation of the soil are established.
Soil erosion has been and remains one of the main causes of a wider phenomenon, that of land degradation. Under this point of view, in addition to erosion, other phenomena of environmental alteration must be considered, among these are to be remembered:
- the accumulation of salts and alkalis which threaten productive agricultural territories in arid and semi-arid regions where irrigation is practiced;
- the location of organic waste and urban landfills it has created hygienic problems and the presence of toxic materials on the surface, in the aquifers and in the soil, reducing their productivity;
- industrial and urban effluents such as heavy metals and detergents, are frequently introduced into the territory and therefore into the soil, creating considerable pollution;
- fertilizers they are soil improvement factors but when applied in excess, they cause soil degradation. The same thing is exercised by the pesticides and herbicides;
- land occupation by urbanization it determines a consumption (often irreversible) of the soils, almost always of those with greater fertility and higher suitability for cultivation.
Erosion is a very complicated phenomenon. It is the result of numerous processes whose mechanics are not yet fully known. The first step towards erosion is the elimination of natural vegetation. Even small rains on moist soil can start the detachment and transport of soil particles; then there is the formation of deeper and closer furrows and a significant removal of earth. As the intensity of rain or wind increases (which represent the main factors of erosion), the slope and the degree of human intervention, erosion becomes more and more widespread, creating damage not only with the removal and loss of soil but also through the sedimentation of detached materials that cover crops, artifacts, buildings, causing the raising of river beds with the relative floods that we all know well.
Man is the main culprit of accelerated and violent erosion. The world population is increasing more and more while non-renewable or hardly renewable natural resources are decreasing. A country's economy largely depends on agricultural products, and erosion can affect a nation's progress and development. This is why it is dangerous to underestimate erosion, especially slow and regular erosion, because it is more serious and subtle, and opens the way to the most conspicuous degradation and the quantitative and qualitative decrease in production.
But let's see what are the main effects of erosion:
- loss of the productive potential of the land with consequent economic loss;
- loss of arable, forest and pasture land with consequent economic loss;
- loss of nutrients from the soil;
- physical loss of soil due to water and wind;
- reduction of soil permeability and its water capacity;
- damage due to floods;
- influence on fishing due to turbidity of the water;
- influence on public health due to swamps;
- damage to the navigability of rivers and lakes;
- damage due to sedimentation in lakes with a reduction in water reserves and the need for greater maintenance.
Erosion is a national problem that must be addressed by applying soil and water conservation practices according to a program valid for the whole country. However, the farmer himself must also contribute through the necessary soil protection techniques.
The historical testimonies indicate that in the eastern regions of the Mediterranean basin, at the time of the ancient Romans, millions of hectares of land became desert. In China, large areas have been eroded and abandoned; from some data obtained in 1934 it appears that the Yellow River carried sediments washed away from cultivated territories for an equivalent thickness of 1 meter of soil for 145,000 hectares (1 hectare = 10,000 m2). Even in Latin America, large, intensely populated areas have had very high losses in soils, especially in those most susceptible to degradation. Severe erosion has also occurred in the USA: it has been calculated that since 1930 about 100 million acres (1 acre = 4,046.86 m2) have been affected by erosion. In Italy the problems related to soil erosion and more generally those concerning environmental degradation are very serious as we can see every year with floods and overflows in many parts of Italy. Politics must move in this direction to preserve the territory and the environment more generally.
Dr. Pio Petrocchi