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X. Research and development priorities
A. Understanding the processes and mechanisms
responsible for:
B. Developing new and innovative management
systems for:
C. Transferring technologies already known
through:
D. Developing the predictive capacity for
extrapolating results from one region to another by:
E. Developing appropriate indicators of
sustainability by:
TRF ecosystems cover a vast area and are a major global resource. Mismanagement of this fragile and ecologically sensitive resource can lead to: (i) degradation of soil by erosion, fertility depletion, decline in soil organic matter content and biodiversity; (ii) contamination of environments through eutrophication and pollution of surface and ground waters; and (iii) decline in productivity. In contrast, a large number of improved and science based technological options can lead to innovative, creative, and sustainable land-use systems. Judiciously implemented and properly managed, these technological options can lead to: (i) enhanced and sustained production; (ii) reversal of degradative trends and improvements in soil quality and soil resilience; and (iii) enhancement of environmental quality through sequestration of carbon into the soil and biomass, and improvement in water quality.
These innovative systems are based on six attributes: (i) soil erosion control; (ii) improvements in soil organic matter content; (iii) enhancement of soil structure; (iv) increase in soil biodiversity; (v) strengthening of nutrient cycling mechanisms; and (vi) increase in soil resilience. Improved systems enhance soil quality and strengthen its resilience, which governs its productivity and environmental regulatory mechanisms. Important characteristics of the improved system are high energy flux, and their soil restorative and environmentally friendly properties. Several proven agricultural practices are crucial to the development of sustainable land-use systems. These practices include:
1. appropriate methods of forest conversion (e.g., manual or shear blade clearing followed by in situ burning and growing a leguminous cover crop to provide an immediate ground cover). (Land clearing and development in the forest region is still a major problem. With increasing labor constraints in the future, mechanized methods of land clearing will be increasingly relied upon. It is therefore important to develop systems of land clearing and management that minimize the degradative effects of mechanized clearing.);
2. adoption of erosion preventive and control measures, including an appropriate combination of mulch farming, conservation tillage, vegetative hedges, and engineering structures;
3. nutrient management based on enhancement of the nutrient capital of the ecosystem through a combination of nutrient cycling, biological N fixation, and supplemental use of chemical fertilizers and organic amendments;
4. adoption of new crop species and improved germplasm adapted to acid soil conditions and harsh environments; and
5. use of new and innovative farming systems based on a synthesis of these practices into efficient, productive, and environmentally friendly land-use systems.
Although a considerable body of research information on the potentials, constraints, and technological alternatives for the sustainable use of TRF is available, a lot remains to be done. There is a need for developing both disciplinary and interdisciplinary research into some key issues, including:
A. Understanding the processes and mechanisms responsible for:
1. rapid soil and environmental degradation in the humid tropics. Why do soils degrade so rapidly after deforestation and conversion to agricultural land use? How can these degradative trends be reversed?
(a) The problem of soil compaction is extremely severe with intensive land use and mechanization. There is a need to develop routine and standardized procedures for characterizing soil compaction.
(b) More basic data are needed for predicting water runoff and soil loss under different land uses and farming systems. There is a need to establish the numerical limits of "soil loss tolerance." Also needed are conceptual and empirical models relating crop yield and soil loss to different levels of management to assess the economic consequences of accelerated soil erosion.
(c) Management of soil structure is important. Why does the structure of the soils of the humid tropics deteriorate so rapidly and how can this be prevented? The development of, crust and surface seal is a major problem in soils containing predominantly low activity clays.
(d) The study of soil dynamics or the evolution of physical, chemical, and biological properties over time in some representative farming systems and varied land uses is needed to establish the cause-effect relationship between land use and soil properties.
2. mineral cycling under intensive and productive land-use systems. How can mineral cycling be strengthened, nutrient losses reduced, efficiency enhanced, and use of the limited resources be optimized? The soils of the humid regions have special toxicity constraints. Research is needed to determine crop adaptation to these nutrient constraints. Basic studies on nutrient and water balance in different farming systems and in different ecologies should provide the basis of management systems to overcome these problems.
3. enhancing soil resilience and improving soil quality. How can mechanisms and processes responsible for enhancing soil resilience and its restorative capacity be strengthened, and used to restore degraded ecosystems?
4. improving soil organic matter content and biomass carbon. The maintenance of high levels of soil organic matter content is critical to the sustainable use of soil and water resources.
5. greenhouse gas emission from soils and vegetation of TRF ecosystems. How can the gaseous emissions from TRF ecosystems be minimized, and soil resources and live biomass be used for carbon sequestration?
B. Developing new and innovative management systems for:
1. decreasing pressure on the TRF so that the rate of deforestation is brought under control. How can the productivity of land already developed be enhanced? Proven innovations and sub-systems to alleviate specific biophysical constraints related to soil and environment should be integrated into farming systems. Methodology should be standardized to facilitate the establishment of farming systems for locale-specific situations on the basis of sub-systems and component technology already developed.
2. restoring the productivity of degraded lands. How can the restoration of vast areas of land that were once productive be achieved,? What are the environmentally friendly systems of soil and vegetation restoration? Restoration of degraded lands deserves high priority, particularly to reduce the need to clear and develop new lands. Methods should be developed to restore and rehabilitate degraded lands. Land evaluation criteria should indicate the time when soil should be taken out of production and put under a restorative and ameliorative phase. Establishing the critical limits of soil properties in relation to severity of degradation is crucial in this endeavor.
3. promoting agribusiness and secondary industry so that economic pressure on land resources is lessened. How can sources of off site income be developed through encouraging agro-industrial development,?
C. Transferring technologies already known through:
1. site-specific, production-oriented, and problem-solving research. How can farmers participate in research so that crucial technology developed at research stations can be applied on-site?
2. identifying policy considerations that promote science-based land use systems.
D. Developing the predictive capacity for extrapolating results from one region to another by:
1. building a base of scientific knowledge that allows the rational use of the land and water resources of TRF ecosystems;
2. developing predictive models to assess the effects of TRF conversion on micro- and meso-climates, hydrology, soil properties, and productivity; and
3. providing guidelines for the sustainable management of TRF resources.
E. Developing appropriate indicators of sustainability by:
1. identifying quantitative criteria for assessing the sustainable use of soil and water resources in the humid tropics; and
2. developing objective and quantifiable indices of sustainability.
There are still many myths about the actual potential and constraints of tropical ecosystems. Although considerable progress has been made in the recent past toward replacing myth with fact, the reasons for the lack of sustainability in tropical ecosystems are not fully understood. The research and development objectives are to achieve high and sustainable yields with less damage to soil and environment.
The TRF ecosystems have a vast productive potential. However, there is a need to create an awareness of the food production potentials and limitations of the TRF ecosystem. These ecosystems also play a major role in global environmental regulatory mechanisms, and should be judiciously managed to enhance production and improve environmental quality.