land management practices and approaches (Steiner, 1996; Penning de Vries et al., 2003). Initiatives such as WOCAT (World Overview of Conservation Approaches and Technologies) or IASUS (International Actions for the Sustainable Use of Soils) and UNCCD may further facilitate such exchange and allow for enhanced cooperation (Hurni et al., 1996, 2006). Drawing on local farmers’ know-how and traditional indigenous techniques may facilitate development of appropriate adapted technologies (Steiner, 1996). Remote sensing, GIS and time-series data may allow for exploration of relationships between soil-quality changes and farm management, local economic and social conditions, and the policy environment. Thus soil-related information may be incorporated in economic and policy modeling for more holistic and integrated analysis of problems and solutions, and allow for the evaluation of different scenarios
and identification of priority areas for action (Scherr, 1999; Penning de Vries et al., 2003).

In summary, approaches to avoid and reverse soil and land degradation should generally consider

• Following a participatory, multidisciplinary systems approach (sectorwide thinking; Scherr, 1999)

• Following the principle of subsidiarity in decision making (decisions should be delegated to the lowest possible level) (Hurni et al., 1996)
• Fitting and targeting the specific environment (regarding development pathways, farming systems, soil types, degree of degradation, etc.; Scherr, 1999)
• Combining indigenous traditional wisdom with modern knowledge and technologies (such as remote sensing, GIS, and simulation modeling)

With regard to the rational management of soil resources, AKST in CWANA will have to target the following major focus areas:

• Increasing or maintaining soil fertility and quality. To counteract negative nutrient balances in many CWANA countries, AKST will have to focus on more efficient use of nutrients, e.g., by developing nutrient management systems for specific soils (Scherr, 1999) or by splitting fertilizer applications. Nutrient inputs will have to be increased, requiring access to and affordability of mineral fertilizers; the complementary use of organic fertilizers from crop residues, manure, compost and green manure will have to be encouraged; and the benefits of biological nitrogen fixation through legumes in rotations, green manure or cover crops will have to be better exploited. Increasing problems of micronutrient deficiencies and depletion will have to be explored and solved. Loss of nutrients will have to be avoided wherever possible by rapidly incorporating manure, combating erosion, etc. Ways will have to be explored to better close nutrient cycles by recapturing nutrients currently discarded in water bodies or dumped as waste elsewhere.

• Adequate organic matter management is particularly essential in CWANA since organic matter decomposes rapidly in high temperatures. Organic matter increases nutrient availability through direct addition and may enhance nutrient use efficiency by improving cation exchange capacity (CEC). Furthermore, increasing the organic matter content in soils improves water-holding

capacity, which is extremely important in the dry areas of CWANA, and enhances soil structure, which reduces susceptibility to wind and water erosion and promotes soil fauna and flora. Increasing organic matter in soils also presents a big opportunity to act as a sink for carbon sequestration, thereby offering potential to mitigate global warming.

• Combating wind and water erosion remains a major challenge in CWANA. Cropping systems, rotations and cropping practices aiming at year-round soil cover should be envisaged wherever possible, although this is not always possible in the dry areas of CWANA. Using harvest residues in mulching, strip cropping (possibly with perennial vegetation), bunds, ridges, terraces, etc., will have to be promoted and profitability of suggested measures assured. Conservation tillage and economically productive cover crops or perennials integrated in crop rotations may be as economical as conventional cropping. Developing low-cost soil conservation and rehabilitation techniques such as control of water flow over land will have to receive major attention (Scherr, 1999).

• Protecting and conserving vegetative cover and quality. Since vegetative cover is key to soil protection, maintaining and—where required—restoring flora and fauna are fundamental for sustainable land use (Scherr, 1999). Appropriate grazing management and protection of land susceptible to degradation (e.g., against inappropriate cropping) will have to receive particular attention in the future.
• Practices to avoid salinization of highly productive irrigated land are well known and consist of improving system- and farm-level water management regimes and the necessary investments in proper drainage systems. AKST will have to investigate diversification options into higher-value crops to justify the required investments. Methods to use saline lands and low-cost options to control or reverse salinization will also have to receive major attention (Scherr, 1999).
• Reducing pollution of soils (as well as of water and air) is particularly important in the more intensive production systems that will probably develop in many areas of CWANA. In this regard, regulating the use of agrochemicals and disposing of agrochemical and livestock waste will have to play a major role in protecting agricultural soils from pollution (Scherr, 1999). Raising awareness and understanding about pollution problems will have to accompany such regulations; lessons learned in other, e.g., industrialized parts of the world will be of particular value.
• Particularly challenging with regard to sustainable land management is the development of new lands—reclamation of land never cultivated before, such as practiced in Egypt. Whereas such new lands hold considerable potential, because their low disease, pest and weed pressure raise the opportunity for organic production, their development may bear great difficulties, in particular with regard to building up and maintaining soil fertility and the high susceptibility of marginal lands to degradation.
• Stopping sand encroachment will represent a major task with regard to protecting productive soils in many