土壤质量与土壤质量指标及其评价

Soil quality: concept,indicators and its assessment

土壤作为一种重要的自然资源可以为人类生产食物和纤维,并维持地球生态系统。土壤也是植物生长的媒介、水、热和化合物的源、水分的过滤器和废物分解的生物介质。土壤与水、气和植物互作并抑制环境的波动。土壤可以调节很多控制水气质量和促进植物生长的生态过程。土壤质量概念的引入使我们更全面地理解土壤,也有助于合理地使用和分配劳力、能源、财政和其它投入。土壤质量也提供了一个通用的概念使得专业人员、生产者和公众明白土壤的重要性。此外,它也是一个评价管理措施和土地利用变化对土壤影响的评价工具。土壤质量由土壤的物理、化学和生物性质组成,MDS已被科学家们提出用于土壤质量评价。国际上比较常用的评价方法主要有多变量指标克立格法、土壤质量动力学方法、土壤质量综合评分法和土壤相对质量法。人类对土地不和谐地利用和管理可以导致全球生物地球化学循环发生改变和加快土壤性质变化的速度,当前世界各地土壤退化相当严重,已日益威胁到人类赖以生存的土地资源。在探讨相关概念的基础上综述了近年来土地利用变化对土壤理化质量和生物质量的影响进展,以引起国内外学者对土地利用变化对土壤质量影响研究的重视,从而为探讨土地利用对土壤质量影响的机理和规律以及退化土地的恢复和区域土地资源管理以及土地的持续利提供理论依据。土壤质量未来的研究应该集中在土壤质量指标与评价方法;土壤质量变化的发生条件、过程、影响因素及其作用机理与时空规律性;尺度问题的研究;土壤质量保持与提高的途径及其关键技术研究。

As one of the vital natural resources, soil plays an important role in producing food and fiber for human beings, maintaining the terrestrial ecosystems and serving as a medium for plant growth, a sink for heat, water, and chemicals, a filter for water, and a biological medium for the decomposition of wastes. By interacting intimately with water, air, and plants, soil can buffer environmental fluctuations and regulate many ecological processes that control water and air quality and promote plant growth. The concept of soil quality defined as the capacity of a specific kind of soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality and support human health and habitation. It was introduced to facilitate soil research by understanding soils more completely and by assisting the decisiorrmaking in the use and allocation of labor, energy, fiscal, and other inputs during the procedure of agricultural production. Consequently, soil quality provides a useful and universal concept for educating professionals, producers, and the public about the importance of soils. It also can be used to assess the impacts of management practices and land uses on soils. Basically, soil quality is comprised of soil physical, chemical, and biological properties. So it is necessary to develop soil quality indicators which describe soil functions in natural and agro-ecosystems： promoting plant growth, protecting watersheds by partitioning and regulating precipitation and preventing air and water pollution. Monitoring the changes in soil quality indicators can provide useful information on the dynamics and trends of soil quality. Many soil attributes could serve as indicators of soil quality. However, they are often highly correlated, making it difficult interpret the significance of changes in selected soil quality indicators. And also the scale problem should be taken into account. Indicators can be adjusted to match the scale of assessment or can be expanded to larger scales using various statistical procedures. A minimum data set （MDS） consisting of a set of soil attributes including soil chemical, physical and biological properties are selected to assess soil quality. The fitness of indicators used for soil quality assessment varies spatially depending on land types or land use, soil function and soil forming factors. Different land-use types may require adjusted critical limits and target values of certain soil functions, and require certain additional indicators for specific assessment. Various approaches, such as multiple-variable indicator kring （MVIK） method, integrated scoring method, dynamics method, and relative quality method, have been used to assess soil quality. Ecologically incompatible human land-use and management practices such as deforestation and soil fertility depletion, cultivation, and land conversion, have greatly altered the global biogeochemical cycles and the dynamics of soil characteristics. Worldwide concern about soil degradation has been given, since it greatly threatened the soil resources on which humans live. Based on the discussion of basic concepts, we synthesized the research advances in the impact of land use changes on soil physical, chemical and biological quality. The problems needed to be solved in soil quality research and key issues for future studies were then analyzed. Much attention should be paid on soil quality indicator and assessment method, mechanism of soil quality change, scaling issue, and the practices of soil quality maintenance in the future studies.