Agriculture Reference
In-Depth Information
tAble 18.3
Predominant soils of the world and their use in crop Production
total historic Area
cropland Area
order
10
6
ha
% of total
10
6
ha
% of total
Alfisols
1330.3
10.2
290
18.7
Andisols
106.0
0.8
50
3.2
Aridisols
1555.5
11.9
40
2.6
Entisols
2167.8
16.6
80
5.2
Histosols
161.0
1.2
0
0
Inceptisols
946.1
7.3
150
9.7
Mollisols
924.6
7.1
290
18.7
Oxisols
1011.7
1.8
300
19.4
Spodosols
347.9
2.7
50
3.2
Untisols
1174.6
9.0
130
8.4
Vertisols
320.0
2.5
60
3.9
Gellisols
1119.9
8.6
0
0
Others
1870.0
14.3
110
7.0
Total
13035.4
100.0
1550
100
Source:
Adapted from Buringh, 1984; Eswaran et al., 1995.
poor and either cannot or do not adopt recommended practices of soil and crop
management. Of the total global land area prone to degradation, area affected in
developing countries is 77% by water erosion, 83% by wind erosion, 97% by loss of
nutrients, 94% by salinization, 100% by pollution, 83% by acidification, and 91% by
waterlogging (Table 18.4). Next to erosion, secondary salinization is the most serious
problem. Of the 270 Mha of irrigated cropland in the year 2003, there were 72 Mha
or 26.5% salinized due to excessive irrigation, lack of adequate drainage, or use of
poor-quality water (Table 18.5). The problem of secondary salinization of irrigated
area is especially severe in Egypt, India, Iran, Pakistan, and China (Table 18.5).
futuRe RIsks of soIl And envIRonmentAl degRAdAtIon
The problem of soil and environmental degradation may be exacerbated during the
twenty-first century because of the confounding effects of many interactive factors.
Important among these are the following:
1. Future increase in the world population will occur in developing countries
where soil resources are already under great stress and the per capita crop-
land area is low and decreasing.
2. The per capita food supply in the world, compared with that of the United States
and other developed countries, is low (Table 18.6) and decreasing in resource-
