Soil Quality and Sustainability
Rattan Lal
Abstract
Increasing human population, rising expectations of living standards, and scarcity of natural resources have made “soil degradation” a major issue of the modern era because it poses a serious threat to human well-being. Consequently, a lot has been said and written on the subject, and the available literature, especially the statistics on land area affected and its adverse impact on productivity, can be extremely confusing. There are several schools of thoughts including those of environmentalists and agriculturists, with often opposing views. For reconciling the opposing views, it is important to understand the processes involved, identify cause-effect relationships, conceptualize the issues and be objective. To do so, soil degradation must be viewed in terms of its adverse effects on present or potential soil functions, and the issue must be discussed in view of other interacting concepts, e.g., soil resilience and soil quality (Table 1). It must also not be confused with land degradation. Land is an all encompassing entity of which soil is one of several components, e.g., water, vegetation, climate. Therefore, the objective of this chapter is to define soil degradation and related concepts in view of its agricultural land use functions. Table 1 Similarities and contrasts between soil resilience, soil degradation, and soil stability http://www.niso.org/standards/z39-96/ns/oasis-exchange/table"> Parameter Resilient soil Stable soil Degraded soil 1. Response to perturbation Changes but recovers following perturbation May not change with disturbance Adverse changes occur that do not recover 2. Effect of management Responds positively to management May not respond to management Low or no ameliorative effects of improved management 3. Productivity Sustains productivity May sustain productivity Productivity is not sustained even with improved management 4. Buffering capacity High High Low or some 5. Environmental regulatory capacity High High Low 6. Soil quality Critical limits of soil properties and processes are flexible Critical limits may be flexible Critical limits are narrow and rigid