Agriculture Reference
In-Depth Information
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Line
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Norm
PgEn
Figure 12.1 Spatial distribution of climatic regions of South America (http://www.fao.org).
du ring 1978-1986 (Mota, 1979) and 1991-1994 (Rossetti, 2001). About
33 % (about 50% in the northeast region) of these losses were attributed to
dr oughts. Maize production also significantly declined due to drought that
oc curred during 1990-91, 1993-94, 1996-97, and 1997-98 (figure 12.3).
[157
Causative Factors of Agricultural Drought
Pr ecipitation and Land Management
The causes for agricultural drought in Latin America can be analyzed
from two points of view. In the first case, drought is intrinsically related
to precipitation deficit during a given period of time, which negatively
affects crops and water resources (Brunini et al., 2002). Second, the poor
management of agricultural lands and exploitation of natural resources
ha ve turned highly productive areas into degraded lands. The decaying of
or ganic matter increases the risk of drought due to the decrease in water
re tention capacity of the soil. Also, soil compaction contributes to drought
oc currence.
El Niño/Southern Oscillation
The most important meteorological phenomenon that causes large-scale
droughts (both spatially and temporally) is El Niño/Southern Oscillation
(ENSO) and La Niña (Alves and Repelli, 1992; Cunha et al., 2001; Mar-
engo et al., 2001; chapter 3). In Brazil, the northern part of the northeastern
 
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