GEO Brasil - UNEP

the state of environment in Brazil
of sand deposits, consolidated or not This process brings
about difficulties in vegetation for the adherence of
vegetation coverage, due to the intense mobility of
sediments through the action of water and wind This type
of degradation is related to humid weather, in which reduced
biological potential does not lead to desertification In Rio
Grande do Sul, where average rain precipitation is 1,400
mm, areas undergoing sandification are located in the
southwest of the State The municipalities involved are
Alegrete, Cacequi, Itaqui, Maçambará, Manoel Viana, Quaraí,
Rosário do Sul, São Francisco de Assis and Unistalda, where
sandy areas occupy 367 Km 2 Besides this number, 1,600
ha of land are at risk of sandification
36 Salinisation
Salinisation, brought about by natural processes or
agricultural use, only occurs in about 2 percent of the
national territory or estimated 85,931 Km 2 (Pereira, 1990) In
general terms, salinisation is related to the occurrence of
little rain precipitation, high water deficit and low natural
draining
Irrigated agriculture is one of the main causes of soil
salinisation in deficient or non-existent draining areas,
especially under semi-arid climate conditions
Under such conditions, if not drained artificially, soils are
likely to become saline, which has been occurring in some
lands in the Northeast The São Francisco watershed is the
soil conditions
most important to irrigation and, in its semi-arid part,
Medium, Sub-medium and Lower Regions, soils are at very
high to medium risk of salinisation On the highest course,
deeper, well-drained soils, and more elevated rain
precipitation result in low to non-existent risk of salinisation
Estimates carried out by the Ministry of the environment in
1998 indicated 495,000 ha irrigated in the Northeast Out of
that, 139,000 ha belonged to public irrigation projects, and
2093 ha were salinisated In addition, 750 ha were at risk of
salinisation Therefore, despite the unavailability of data
about salinisation in private areas, and even considering
that it represents a constant risk under soil and climate
conditions in the Northeast, salinisation is not relevant as a
soil degradation process in the country, especially in the
other parts of the country, as general conditions do not
allow for salinisation to occur
37 Land burning
Burning occurs all over Brazil, in itinerant cultivation
performed by Indians and backwoodsmen, or in highly
intensified production systems, such as sugar cane and
cotton, causing local and regional environmental impacts
It is used for clearing, preparing harvests, renewing pastures,
burning residues, eliminating plagues and diseases, hunting
and many others There are several types of burning moved
by different interests in different locations and production
systems
Fire directly affects physical, chemical (N and S deletion)
and biological characteristics of the soil It also deteriorates
air quality, reduces biodiversity and harms human health If
uncontrolled, fire may damage public and private property
(forests, fences, telephone and transmission cables,
buildings and others) Burning may also alter the
atmosphere composition and exert a negative influence
over global changes
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Contamination by urban, industrial and
agrochemical residues
The main impacts on soils is potential contamination by
the use of pesticides and overexploitation of land with a
low agricultural potential, especially with pastures
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