ABSTRACT
A project of the United Nations Environmental Program on Global Assessment of Soil Degradation concluded, “Nearly 40% of all agricultural land has been adversely affected by human-induced soil degradation, and over 6% would require major capital investment to restore its original productivity” (1). It is, therefore, not surprising that, among regulatory authorities, there is a strong desire for the development of sensitive indicators to assess soil degradation. Properties that provide a snapshot assessment of the status of a soil can determine whether a management practice has had an adverse effect on soil “health” and productivity and, better still, can predict whether a practice will have an adverse effect if it is continued. This has been one of the major drivers of the worldwide research effort on soil quality defined as “the capacity of a soil to function, within ecosystem and land-use boundaries, to sustain biological productivity, maintain environmental quality, and promote plant and animal health” (1). This topic has been the subject of numerous reviews, such as those found in the Soil Science Society of America Special Publications 35 (2) and 49 (3). We do not wish to enter the debate concerning a potential role for enzyme activity measurements in the wide soil-quality context-this topic has already been reviewed (4-6)—but to focus on the application of soil enzymes to scenarios in which soil degradation is demonstrable, or at least strongly suspected to be a likely outcome of a particular land-management practice.
