Soil is the upper layer of the Earth’s surface and forms the base on which our planet’s life has developed on land. Soil can be regarded as living, as it is home to many organisms and is subject to continuous cycles of generation and decay.
Soil is far more than an inert medium: it is a dynamic, living system made up of organic and mineral constituents. It features a network of pores that hold liquids and gases. Soil provides a habitat for populations of bacteria, fungi, worms and rodents.
Because its rate of formation is so slow, soil is considered to be a non-renewable resource. Soil formation is influenced by the parent materials (minerals), living organisms (plants, animals, micro-organisms and human activities), climate, topography and weather. Soil is static and thus acts as an enormous receptacle for any type of pollutant mobilised by different triggers (such as acidification) and released into the environment. Since these substances remain in the soil far longer than in the air or water, their impacts are often hidden for a long time.
The most important functions of the soil are to filtrate underground water; hold and supply the nutrients and water necessary for plant growth; provide a habitat for different organisms; contribute to the process of decay; absorb, store and reflect the Sun’s energy; and provide a basis for the existence of human beings and other animals.
Conflicts may arise when different soil functions are in competition. For many centuries, soil functions were maintained without great difficulty. Problems arose at the beginning of the 20th century, when increasing development disrupted the soil’s ecological functions. Settlements and infrastructure expansion, industrial and transport development, waste dumping, mining for raw materials and intensive agriculture all exert pressure on the soil. Soil properties usually deteriorate as a result of human activities, leading to the degradation of one or more of the soil's functions.
A balance needs to be found among all the competing interests and soil use must be harmonised at regional level in order to protect the soil and safeguard its functions.
Soil degradation occurs
when human activities reduce the existing or future capacity of
the soil to support life. The most severe soil degradation
processes are outlined below.
Soil recovery
The recovery of the soil's properties
is not an easy task:
Clean-up costs are often so high that the only practical approach is for the owner of the polluted property to share the cost with society. At the same time, maximum technical, financial and legislative resources must be directed towards preventing new pollution.
Despite its comparatively
small size, the territory of Belarus is characterised by fairly
diverse natural conditions and soil formation factors. This
diversity is due to the complexity of the terrain, the variety of
soil-forming materials, and the significant variability of the climate and
vegetation cover. The diversity of natural conditions in the
different regions of the country determines the formation of the soil
in the respective areas.
The 2006 national
report of Belarus on the implementation of the UN
Convention to Combat Desertification mentions chemical contamination as one
of the factors contributing to land degradation. Chemical contamination is characteristic mainly for
cities and their surrounding areas, roadsides, zones affected by
waste disposal, agricultural land and industrial sites.
According to the National Action Plan on the Rational Use of Natural Resources
and Environmental Protection of the Republic of Belarus 2006–2010, the total area of soil with dangerous levels of contamination in urban areas is estimated at 78,000 hectares; in areas
near roads 119,000 hectares; on agricultural land 10,000
hectares; and in areas used for waste disposal 2,500 hectares.
Over
a five-year period, in the framework of the National Environmental
Monitoring System (NEMS), the accumulation of petroleum products and
heavy metals — and, to a lesser extent, sulphates and nitrates — was noted in soil samples from 44 cities in Belarus. Petroleum
contamination was characteristic of soils in all surveyed cities. In
50 percent of settlements, the oil content of the soil was five to 15 times higher than the maximum
permissible concentration (MPC). Cadmium, zinc and lead were
the main pollutants among heavy metals. Cadmium contamination was typical in 72 percent of the surveyed cities, zinc in 77 percent, and lead in 61 percent. There were many instances of contaminant levels being double, or more than double, the MPC, including cadmium (in eight cities),
zinc (in 14 cities) and lead (in nine cities).
High concentrations of copper were found in four cities. Soil
contamination from nickel and manganese was not noted in the
surveyed cities. Contamination by sulphates at levels between one and one and a half times the MPC was observed in 39 percent of surveyed
cities. Samples from only three cities revealed excess
concentrations of nitrates.
In the course of local land monitoring, undertaken as part of the NEMS in 2007, zinc and
cadmium were identified as priority pollutants in soil samples taken
from industrial areas used for mechanical engineering and
metalworking factories, while copper, nickel and chromium were present to a lesser
extent. The metal content in samples taken from some sites exceeded MPCs by several orders of magnitude.
Polycyclic aromatic
hydrocarbons (PAHs), petroleum products and polychlorinated
biphenyls (PCBs) are the main soil pollutants emitted from factories producing fuel and energy, chemicals and
petrochemicals. Soil at industrial sites devoted to
the production of building materials are contaminated with
arsenic. At some sites, arsenic levels are several times higher than
normal.
In Belarus, agricultural practices that cause soil
contamination include the excessive use of pesticides and mineral fertilisers, which leads to the accumulation of chemicals in the soil, and excessive irrigation with
wastewater from livestock farms.
Strategies to
prevent soil contamination are complex and multifaceted. A
transition to low-waste and zero-waste technologies should take place in the
industrial and energy production sectors. In the agricultural sector, there is a need to introduce effective agronomic and biological pest control methods and low-hazard pesticides; to reduce and hopefully
eliminate environmental contaminants in practice; and to employ science-based technologies when using chemical fertilisers.
In terms of erosion, in Grodno region 1.7 percent of arable land is
exposed to wind erosion; in Gomel
region 1.6 percent; in Minsk region 1.1 percent; and in Brest, Vitebsk and Mogilev
regions 1 percent.
Annual humus loss in
Belarus is estimated at 180 kg per hectare; annual nitrogen loss at up to 10
kg per hectare; and annual potassium phosphate loss at up to 6 kg per hectare.
The cultivation of row
crops could be responsible for the loss of 2 to 3 tonnes of peat per
hectare in the Palessie area of Belarus.
The following laws of the Republic of Belarus cover some of the issues
related to the use and protection of soil resources:
Several institutions in Belarus are involved in the study of soil resources: