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全世界约有40%的土地属于干旱和半干旱区,在这些地区居住着约7亿人口。近60%的旱地分布在发展中国家。尽管在今后旱地将继续生产世界绝大部分粮食,以满足人口增长的需要,但其产量极低。在80年代,非洲亚撒哈拉沙漠的一些国家,人均占有粮食急剧下降,其原因主要是自然资源基础,即耕地的恶化。限制这些旱区农产量提高的因素主要是雨水分布不均,雨量不足,土壤质地太砂,它们肥力低,有机质少保水力差。这些土地管理粗放,并大面积遭受荒漠化危害和风和水的侵蚀,从而丧失生产力。提高旱地生产力,增强其稳定性和持久性的关键是防止土壤资源的进一步恶化。为此,应对土壤和水分进行管理,并合理而经常地增施有机改良剂。本文讨论在干旱和半干旱地区建立持久的水土保持和生产系统的若干战略。
About 40% of the world’s land belongs to arid and semi-arid areas, where some 700 million people live. Nearly 60% of drylands are located in developing countries. Although in the future drylands will continue to produce the vast majority of food in the world to meet the needs of population growth, their output will be extremely low. In the 1980s, some countries in the sub-Saharan African subcontinent had a sharp decline in food per capita, mainly due to the natural resource base, namely the deterioration of cultivated land. The factors that limit the increase of agricultural output in these arid areas are mainly the uneven distribution of rainwater, insufficient rainfall, too-sandy soil texture, low fertility and little organic matter. The land is extensively managed and is largely deprived of its productivity by desertification hazards and erosion by wind and water. The key to improving productivity and enhancing stability and sustainability in drylands is to prevent further deterioration of soil resources. To this end, soil and water should be managed and organic amendments should be rationally and often applied. This article discusses a number of strategies for establishing sustainable soil and water conservation and production systems in arid and semi-arid areas.