Soil Enzymes as Indication of Soil Quality

Abstract

Soil, water and air are natural resources as well as pollution reservoirs. Soil quality can be changed by pollution, ecological perturbations and agricultural practices. Soil quality can be 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''(Karlen et al. 1997). Preserving soil quality should be needed for sustaining of life and human nutrition. Soil enzymes are used as soil quality indicators for quick response of changes for environmental stress, pollution and agricultural practices much more sooner (1--2 year) than other soil properties (organic matter); easy to measure (relatively simple procedure), having relations with plant productivity, soil quality parameters (organic matter, soil physical properties, microbial activity, and microbial biomass), and biogeochemical cycle; and being integrative. This chapter mainly covers three distinct effects for changes in soils: (1) pollution (heavy metals, pesticides, industrial amendments or contaminants, hydrocarbons, acid precipitations, industrial air pollutants, sewage sludge, and waste usage), (2) ecological perturbations(land use, devegetation and revegetation, changing climatic conditions, and forest fires), and (3) agricultural practices (irrigation, fertilizers, amendments, different management and farming systems, crop rotation, and tillage).