Soil erosion is the
natural force that creates ravines and valleys and destroys mountains. Further
we will consider this natural process in more detail. At
the photo - the rapid growth of ravines in the Novosibirsk region,
Russian Federation
What is soil
erosion?
Soil erosion is the displacement of the topsoil; it is a
form of soil degradation.
Soil erosion is a natural process that is caused by the
action of the activity of erosion factors:
According to these agents, erosion is sometimes subdivided
into:
water erosion
glacial erosion
snow erosion
wind (aeolian)
erosion
zoogenic erosion
anthropogenic
erosion
There are two main types of
soil erosion - water erosion and wind erosion.
Water erosion of soil - the
displacement of soil from surface of field, including the soil and and subsoil,
followed by their deposition in relief depressions and water bodies by action of
water flows: rainfall and surface runoffs.
Short film
about - what is water soil
erosion
Wind (eolean) soil erosion -
the blowing of soil particles by a strong wind.
Dust storms are a manifestation of wind
erosion. Dust storms are especially harmful to agricultural regions with a
lot of arable land, as well as where there are a lot of sandy soils. Dust
storms destroy the top, fertile soil layer, humus - thereby greatly reducing
fertility and causing direct financial harm
Water and wind erosion
always act together on the soil.
The definition of soil
erosion involves the destruction of the surface layer of the Earth due to the
effects of precipitation and wind. Erosion is estimated to have destroyed nearly
2 billion hectares of arable land over the past two centuries. For comparison -
now agricultural land is cultivated on an area of 1.5 billion hectares.
A film about what soil is and how billions of dollars are lost due to soil
erosion around the World. This film tells the reality of soil resources around
the world, covering the issues of degradation, urbanization, land grabbing and
overexploitation; the film offers options to make the way we manage our soils
more sustainable (source:
IASS Potsdam)
Types of soil erosion are
depending on what the main factors have a destructive effect to the soil.
There are two main factors -
water and wind, and the combined action of water and wind.
What causes and types of soil
erosion?
For reasons of occurrence, a
distinction is made between natural and anthropogenic erosion caused by the
consequences of human activities, for example, the felling of forest belts.
Water erosion of soil is subdivided into the following
types:
Rainfall erosion - soil
destruction by blows of rain drops
Surface runoff erosion -
washout of material from fields, especially pronounced on slopes
The formation of ravines,
gullies, valleys as a result of the action of strong flows / runoffs of water
(more strong type of surface runoff erosion)
The
restoring stream banks can harm to
agricultural fields, annually destroying a portion of the
arable land. If part of the field is washed away by water, then the annual
losses can be very significant and amount to hundreds thousands of dollars
per year, since each ton of black soil
or floodplain fertile soil is expensive
Erosion of man-made origin -
under man-made impacts associated with plowing, soil exposure as a result of
destruction of vegetation and forest belts, works during construction,
quarrying, dumping, deforestation, etc. There is a sharp increase in the volume
of soil losses in as a result of erosion, due to the destruction of natural
obstacles to soil washout
Water erosion of soil - displacement of the soil, seeds and
seedlings from the field by rainfall and surface runoffs
Soil erosion also differs in the speed of the processes
occurring:
normal or geological
(natural)
fast,
destructive, most often - anthropogenic
But anthropogenic erosion is
not always will be fast.
Irrigation soil erosion is
one of the types of anthropogenic soil erosion, which occurs when the
regulations, rules and norms of irrigation in irrigated agriculture are not
observed. And more often it is associated with the use of such outdated types of
irrigation as surface irrigation or improper sprinkling. Also, improper
irrigation contributes to soil salinity.
Normal erosion is present in
areas with natural vegetation cover as well as in artificially created pastures.
In such conditions, the soil can recover, since the process of soil formation
under such conditions does not stop.
Fast erosion occurs when
natural vegetation is removed, such as through tillage. This happens when
agricultural land is misused.
This process is present in
all fields, but it is especially pronounced in areas where there is a dissected
relief - slopes, hills. And it manifests itself very strongly - in the steppe or
forest-steppe, with neglect of anti-erosion measures.
The most dangerous type of
water erosion of soil is the formation of ravines, which can form even from
small surface runoff. The
control of this type erosion is difficult due to high financial costs and in
most cases made by planting of shrubs and forests along the edges of ravines.
In this case plants keep soil with their roots and strengthen the slopes
The formation of a ravine occurs rather quickly. The
streams of water first wash out a small gully, then a small ravine, which can
become simply gigantic in two or three seasons. However, it happens that a large
ravine is formed during just one spring.
And the financial costs of
eliminating such, even small gullies that threaten fields and buildings, can be
very significant.
Wind soil
erosion damage
Wind erosion can cause
severe damage, both over a long time and in just a few hours. Dust (black)
storms quickly carry away the topsoil, sometimes for many hundreds of kilometres.
Sometimes such dust, settling, falls asleep on whole bodies of water.
An example from the 50s of
the last century can be cited. Then, during the development of virgin lands in
the steppes of Kazakhstan and the western part of the Altai Territory, moldboard
plowing was used. After sowing, a drought began, and then a strong wind came to
the territory from the West. He took away a significant part of the fertile
layer of soil. Dust from the Kazakh and Altai steppes settled even in the
Krasnoyarsk Territory, at a distance of 1000-1500 km. These soils have not
recovered until now.
Water and wind erosion
always occur simultaneously. In this case, the sequence is as follows. In spring,
streams of water wash away the soil. Then soil dries up. The next stage - the
dried soil turns into dust. This happens most often when the soil is tilled
repeatedly. Then, the dusty soil is blown out and transferred to other
territories.
To reduce the blowing off of
the fertile soil layer, dry soil should not be cultivated. Snow retention is
also very effective through the use of modern technologies that allow you to
leave stubble in the field -
No-Till & Strip-Till
and
CTF.
The use of special snow
plows for snow retention is much less efficient financially, but is often common
in countries such as Kazakhstan and Russia.
In the case when heavy rains
begin in summer, the soil that has turned into dust is displacement off by small
and large rain streams. If the rains continue, the soil is runoff away from
field to a much more extent and eroded. That is, the process of formation of
ravines begins.
Soil erosion in the World
Global rates of soil displacement by water erosion.
The map illustrates the soil erosion rates divided into seven classes
according to the European Soil Bureau classification. The colour gradation from
green to red indicates the intensity of the predicted erosion rates. Being a
global model, the map also covers areas where there is no direct anthropogenic
impact. Borelli, P. et al., 2017 (source of picture:
JOINT RESEARCH CENTRE)
It poses a
financial threat to countries that are the leading exporters of grain in the World, that cultivate the soil and grow field crops in a
temperate climate zone and in dry climate zones: the USA, Canada, Australia,
Ukraine, the European Union, the Russian Federation, and Kazakhstan.
In Ukraine, there is strong
soil erosion in the steppe and forest-steppe zones, as well as in other soil and
climatic zones where fields are plowed.
In the Russian Federation,
wind erosion is manifested in all regions where there is agriculture and where
the soil is cultivated. The area at risk is more than 45 million hectares,
including 38.7 million hectares of arable land.
In Central Asia (Kazakhstan,
Uzbekistan, Kyrgyzstan, Turkmenistan) - in the foothills and valleys, where
agriculture and irrigation are developed, water erosion of soil is highly
developed.
In these regions, the
transition from surface irrigation through irrigation ditches to drip irrigation
helps to reduce soil erosion in
orchards, vineyards and vegetable growing. In
more desert regions, wind erosion is very developed - blowing off the topsoil,
both in the warm season and in winter, when there is no snow.
Map of rainfall erosivity.
South
America, the Caribbean, Central Africa and parts of Western Africa and South
East Asia have highest rainfall erosivity (source of
picture:
JOINT RESEARCH CENTRE)
In Brazil, Argentina and
other countries of South America and countries of the tropical and subtropical
belt, soil erosion is very common, caused by the deforestation of natural
forests and shrubs to create plantations of various crops, vegetables,
orchards,
and vineyards.
Zoogenic erosion from
domestic animals is present in Africa, Central Asia, in a dry climate, in a
desert climate, in mountainous regions, and where grazing livestock (sheep, cows,
goats) is developed, with a heavy load on pastures and a very high number of
animals (the maximum possible numbers), often domestic animals eat up all
vegetation and the soil degrades, and huge areas become unsuitable for pastures,
desertification occurs.
Largely affected by land
erosion in countries such as Canada, USA, China, India, Australia, most African,
European and Asian states. For example, in just three centuries, the Sahara
Desert moved 400 kilometres to the South.
In the United States, by the
second half of the 1950s, erosion had destroyed nearly 40 million hectares of
arable land. At that time, almost 115 million hectares of arable land were
destroyed or seriously damaged there. Another 313 million hectares were damaged
by erosion.
But now the United States,
Canada and Australia are spending huge sums on the education of farmers and the
fight against soil erosion, so in these countries work to combat erosion is
carried out regularly, modern methods are being introduced that have already
significantly reduced soil erosion and agricultural land degradation:
planning of roads,
dams and territories into square sectors
drainage systems,
directing water flows and facilitating drainage
drip irrigation,
including SDI subsurface drip irrigation
investments in
forest belts creation
use of modern
machines and machine management systems
Therefore, in these
countries, the risks of erosion are the smallest, in comparison with other
countries engaged in the cultivation of field crops and deforestation.
Soil conservation technologies that leave stubble on
the surface of the soil help protect the soil from erosion.
At the photo - field of
sunflower that sowing by
Strip-Till technology in Ukraine
Consequences caused of soil erosion
Due to the erosion of the country's
economy and global economy, the damage is enormous.
Global status of human induced soil
degradation (source of
picture:
UN FAO).
Many fields in World by by agricultural action of humans are degraded and it
very significant financial losses!
The potential of soil fertility decreases, the chemical and physical properties
of soils deteriorate, and the biological activity of the soil decreases. As a
result, the yield decreases and the quality of agricultural products. The
efficiency of the use of fertilizers and pesticides also decreases. As a result,
huge amounts of money are lost due to soil erosion.
Erosion processes are present literally everywhere. Soil erosion leads to
weathering of humus and disruption of the ecological balance, which can already
lead to an ecological disaster.
During dust storms, the loss of the humus layer is enormous. In a dust storm on
a plowed field, the loss of humus per day can be more than 10,000 years in a
field with natural grass cover!
In some zones, the erosion of fertile soils is 5-15 times higher than their
formation.
Soil erosion
control
Currently, various technologies and ways to solve the problems of soil erosion
are used to protect soil from erosion:
planning of roads, dams and territories into square sectors
drainage systems, directing water flows and facilitating drainage
reduced use of plowing
modern technologies make it possible to completely abandon pre-sowing
cultivation when growing late crops - sunflower,
soybeans, corn, sorghum - thus reducing soil erosion and moisture loss before sowing these
crops
leave stubble in the field for the winter, snow retention, limitation of
runoff
drip irrigation, including SDI subsurface drip irrigation
investments in forest belts
mulching and soil covering in vegetable growing
use of modern machines and machine management systems
regulation of the number of sheep, goats and cows in pastures
transfer of arable land to pastures, orchards, vineyards and plantations of
energy crops, development of the
greenhouse business
strict ban on cutting down forest belts and burning stubble
prevention of fires
The main methods are: crop rotations and abandonment of fallow (alternation of
crops in time and in the territory or only in time), providing soil protection,
Strip-Till,
CTF and cover crops, creating meadows and pastures on poor soils and
washed-out slopes, using cover crops and grass aisles in orchards, berry and
vineyards.
The protection of soils from wind erosion is facilitated by such a method as
planting forest belts and shrubs (forest melioration).
A good effect is provided by irrigation and drainage facilities.
A positive result is brought by the stubble left in the field for the winter
(No-Till & Strip-Till), and the limitation of snow drift in winter conditions
- the use of shields that provide snow retention in places where there are no
forest belts (in forest belts breaks).
Rolling snow in strips, its blackening, the use of snow plows is much less
effective and in most cases, like, for example, the introduction of saltpeter
(or any nitrogen fertilisers) by
frozen soil, are fake and ineffective agricultural practices.
An excellent effect, a decrease in erosion and an increase in soil fertility, is
also provided in the case when there is a rejection of pure fallows. Modern
technologies make it possible to abandon pure fallows even in arid climates and
when using crop rotations saturated with sunflower. Pure steam is a very
outdated system and money down the drain! After all, if nothing is grown on the
field, then the profit will not be obtained, and the soil will be subject to
severe erosion.
Terraces
on slopes are a good way to
protect plants and soil from erosion by strong flows of water after rains
action. As on this photo - famous domestic stone terraces of grape plantations
in Hessigheim, Germany (photo source:
Needpix)
Against soil erosion, only joint, comprehensive use of all methods is effective.
All investments and additional costs aimed at preventing and preventing soil
erosion, the using of modern technologies (Strip-Till,
CTF, cover crops, etc.).
Contrary to popular belief that these investments have a long payback period -
they can pay off in just for several years, a higher yield, an increase in soil
fertility, an improvement in the microclimate. And also measures aimed at
combating erosion, such as the creation of forest plantations, not only reduce
financial risks, but also improve the quality of life!
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