Agriculture Reference
In-Depth Information
18
Soil Science:
Management and
Conservation
R. Lal
contents
Abstract .................................................................................................................. 283
Introduction............................................................................................................ 284
Soil Area under Natural and Cultivated Ecosystems ............................................. 284
Future Risks of Soil and Environmental Degradation ........................................... 286
Basic Principles of Management and Conservation of Soils ................................. 290
Enhancing the Soil Organic Matter Pool ............................................................... 292
Managing Soil Structure and Enhancing Aggregation........................................... 295
Nutrient Management ............................................................................................ 295
Water Management ................................................................................................ 296
Biofuel.................................................................................................................... 298
Conclusions............................................................................................................ 299
References.............................................................................................................. 299
AbstRAct
Conversion of natural to agricultural ecosystems, involving 1070 million hectare
(Mha) of forests and woodland/shrubland and 660 Mha of grassland, and subse-
quent soil cultivation caused depletion of the soil organic carbon pool, disruption in
elemental cycling, and increase in susceptibility to degradation by erosion, salini-
zation, and fertility depletion. The severe problem of soil degradation, caused by
extractive farming practices and fragile soils, is likely to be exacerbated by the pro-
jected climate change. Despite the severe problem of soil degradation, cereal yields
in developing countries must be increased by 35 to 63% by 2025 and 58 to 121% by
2050 without and with any dietary change, respectively. The global fertilizer use is
projected to increase from 136 million nutrient tons in 2000 to 165 million tons in
2015 and 188 million tons by 2030, and most of the projected increase is to occur in
India, China, and other Asian and Latin American countries. Similarly, global irri-
gated land area is projected to increase, with most expansion in South and East Asia,
but not in sub-Saharan Africa. Strategies of improving soil quality include increas-
ing soil organic matter pool, improving soil structure, and strengthening elemental
283
