A new approach to water quality modelling and environmental decision support systems
Answers
Answered by
0
The problem of land degradation
PRESSURES ON THE REGION'S AGRICULTURAL LAND ARE LEADING TO EXTENSIVE LAND DEGRADATION. THE CAUSES ARE POVERTY, LAND SHORTAGE AND INCREASING POPULATIONS
In 1992 developing countries in Asia and the Pacific accounted for just less than 54 percent of the world population - nearly 3000 million people. Yet these countries had only 17 percent of the world's land resources.
Even so, countries in Asia and the Pacific are relatively well fed compared, for example, to much of Africa and parts of Central and South America. This is because they have made profitable use of new agricultural technology, such as fertilizers, high-yielding crop varieties, mechanization and irrigation. During the period ]961-85, 93 percent of the region's increase in cereal production was due to increased production inputs. As a result food production has more than kept pace with population increase.
While agricultural productivity has risen dramatically, the cost in land degradation has been high. Large areas of the region's cropland, grassland, woodland and forest are now seriously degraded. Water and wind erosion are the major problems but salinity, sodicity and alkalinity are also widespread; water tables have been over-exploited; soil fertility has been reduced; and where mangrove forest has been cleared for aquaculture or urban expansion, coastal erosion has been a common result. Finally, urban expansion has become a major form of land degradation, removing large areas of the best agricultural land from production.
The effect of these forms of land degradation on cereal production has so far been masked by the increasing levels of agricultural inputs that are used. However, production of other crops, such as pulses, roots and tubers, has now begun to decline. It is no coincidence that these crops arc grown on land with low production potential, where rates of land
PRESSURES ON THE REGION'S AGRICULTURAL LAND ARE LEADING TO EXTENSIVE LAND DEGRADATION. THE CAUSES ARE POVERTY, LAND SHORTAGE AND INCREASING POPULATIONS
In 1992 developing countries in Asia and the Pacific accounted for just less than 54 percent of the world population - nearly 3000 million people. Yet these countries had only 17 percent of the world's land resources.
Even so, countries in Asia and the Pacific are relatively well fed compared, for example, to much of Africa and parts of Central and South America. This is because they have made profitable use of new agricultural technology, such as fertilizers, high-yielding crop varieties, mechanization and irrigation. During the period ]961-85, 93 percent of the region's increase in cereal production was due to increased production inputs. As a result food production has more than kept pace with population increase.
While agricultural productivity has risen dramatically, the cost in land degradation has been high. Large areas of the region's cropland, grassland, woodland and forest are now seriously degraded. Water and wind erosion are the major problems but salinity, sodicity and alkalinity are also widespread; water tables have been over-exploited; soil fertility has been reduced; and where mangrove forest has been cleared for aquaculture or urban expansion, coastal erosion has been a common result. Finally, urban expansion has become a major form of land degradation, removing large areas of the best agricultural land from production.
The effect of these forms of land degradation on cereal production has so far been masked by the increasing levels of agricultural inputs that are used. However, production of other crops, such as pulses, roots and tubers, has now begun to decline. It is no coincidence that these crops arc grown on land with low production potential, where rates of land
Similar questions