Page 52 - Soil Degradation, Conservation and Remediation

1.8 Laws of Sustainable Soil Management 37

Table 1.3 Extent of degraded lands in different regions of the world
Agricultural land Permanent pasture Forests
Total Degraded Total Degraded Total Degraded
Region Mha Mha % Mha Mha % Mha Mha %
Africa 187 121 65 793 243 31 683 130 19
Asia 536 206 38 978 197 20 1,273 344 27
South America 142 64 45 478 68 14 896 112 13
Central America 38 28 74 94 10 11 66 25 38
North America 236 63 26 274 29 11 621 4 1
Europe 287 72 25 156 54 35 353 92 26
Oceania 49 8 16 439 4 19 156 12 8
World 1,475 562 38 3,212 685 21 4,041 719 18
Kertesz ( 2009 ), FAO ( 1990 ), and Scherr ( 1999 )

1.7.4 Extent of Soil Degradation

.
Some 38 % of the agricultural area of the earth can be considered as degraded The
share of degraded territories in Africa is 65 %, in Central America 74 %, and in
South America 45 %. The proportion of degraded pasture and forests is much
smaller 21 % and 18 %, respectively. Considering only used land (agricultural area,
permanent pasture, and forests), the proportion of degraded area is 23 % and that of
strongly degraded land is 14 %. Table 1.3 shows the distribution of degraded lands
in different regions of the world.
An estimated 38 % of the area (749 M ha) affected by human-induced soil deg-
radation was slightly degraded, 46 % (910 M ha) was moderately degraded, 15 %
(296 M ha) was strongly degraded, while less than 1 % (9.3 M ha) was extremely
degraded (Oldeman 1994 ). Adverse effects on soil health and soil quality in Asia
arise from nutrient imbalance in soil, excessive fertilization, soil pollution, and soil

loss processes ( Zhang et al. 1996a , b ; Hedlund et al. 2003 ). In Africa, three-quarters
of farmland is severely degraded (Eswaran et al. 1997 ; Stocking 2003 ). As a result,
Africa cannot produce enough food to keep pace with its needs, and per capita food
production is declining largely due to loss of soil health and soil quality (Lal et al.
1997 ; Lal 1998 ).

1.8 Laws of Sustainable Soil Management

Soil resources can never be taken for granted. Many civilizations, including
Mayan, Incas, Indus, and Mesopotamia, are now extinct because they ignored
their soil resources. In the context of increased global threat of soil degradation,