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In view of the ever-increasing demand on limited and fragile resources, the question most often asked is whether soil productivity in TRF ecosystems can be sustained with intensive and continuous farming. The available research data indicate that most tropical soils can be intensively cultivated and produce high and sustained yields by adopting BMPs based on an ecological approach to agriculture. In this connection, land-clearing techniques play an important role. The effects of improper land-clearing methods are observed even 8-10 years after the land has been cleared, and especially when the overall soil fertility has drastically declined. Adopting a land-use system that may produce, say, 60-80 per cent of maximum returns and that avoids causing environmental degradation is a better choice than land-use systems that bring high short-term returns but severely degrade the resource base.
An optimum resource utilization should be based on scientific data obtained through well-designed and adequately equipped long-term experiments. To start meeting this objective, additional research information is needed on evaluating the following:
· land capability and the development of criteria for the choice of rational land use and for appropriate methods of removing vegetation,
· the economic and environmental consequences of different land-use systems,
· methods of restoring forest vegetation and soil quality degraded by land misuse,
· ecologically compatible methods of Imperata control,
· adaptability of those methods of soil and crop management that enhance production from existing land, thereby reducing the need to clear new land.
Considering the limited resources available and the urgent need to use forest resources efficiently, it is important that priorities are defined and research goals are sharply focused. A coordinated effort is needed to achieve these objectives.
Table 9.19 Land restorative techniques
|Soil degradative process||Strategies||Land restorative techniques|
|Soil compaction||Enhance soil structure||Grow planted fallows and deep rooted perennials|
|Improve aggregation||Use mulch farming techniques|
|Enhance activity of soil fauna, e.g. earthworms||Avoid excessive vehicular traffic|
|Use subsoiling discriminatingly and judiciously|
|Soil erosion||Divert run-on||Isolate the area|
|Prevent runoff||Construct diversion channels|
|Minimize raindrop impact||Establish permanent ground cover|
|Enhance soil structure||Use fertilizets and manures|
|Establish vegetative hedges on the contour|
|Establish micro-catchments and water-spreading devices to enhance water infiltration|
|Nutrient depletion||Stop fertility mining practices||Take land out of production and establish planted fallows|
|Use balanced fertilizer||Augment nutrient capital by the addition of chemical and organic fertilizers|
|Develop nutrient recycling mechanisms||Establish native trees and deep rooted shrubs to facilitate nutrient recycling|
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