FACTORS AFFECTING SOIL-EROSION HAZARDS AND CONSERVATION NEEDS FOR TROPICAL STEEPLANDS

Understanding the basic processes and factors that are responsible for inducing land degradation, particularly soil erosion and associated p henomena is critical to the conceptualization, design, and implementat ion of productive, stable, and sustainable agricultural systems. This is particularly so on steeplands where the potential for soil erosion and runoff water losses is high. The productivity and degradation haza rds on these lands are determined by the site's climate, soil and topo graphy. However, their uniqueness lies more with their topographic con straints than with other factors. Use of steeplands is an increasingly common situation in the tropics because of high population pressures and continuing encroachment on hilly lands. Erosion potential and actu al erosion in these settings may exceed tens or even hundreds of tons of soil loss per hectare per year; thus the selection and design of cr opping systems, land management systems, and water management systems must be tailored to attain effective runoff and erosion control in ord er to avoid their detrimental impacts both on-site and off-site. Contr ary to the customary arguments for the 'long-term' nature of erosion i mpacts; enhancing the conservation-effectiveness of rainfed fanning on tropical steeplands can be shown to provide both short- and long-term benefits to the farming system, the overall economy, and the environm ent. Productivity-enhancing crop and soil and water conservation manag ement approaches (biological measures) may be more important than stru ctural measures in imparting long-term sustainability. Incorporating i ndigenous knowledge into project design should be emphasized to assure the farmer's involvement and cooperation in planning, implementing, a nd maintaining conservation measures.