Soil Quality Basics

Soil quality is the ability of a soil to perform functions that are essential to people and the environment. Soil quality is not limited to agricultural soils, although most soil quality work has been done in agricultural systems. Soil quality definitions emphasize several features, such as:

Management affects on soil properties:

Soil quality assessments focus on the dynamicSoil characteristics that can change in response to land use changes., or management-affected, properties of soil, such as nutrient status, salinity, and water-holding capacity. These properties are assessed in the context of the inherentSoil properties that do not change with land use. capability of a particular soil. Go to Inherent and Dynamic Soil Quality for more information. To learn more about how management practices change soil propertiesChemical, physical, or biological characteristics of soil that can indicate its level of function of ecosystem services. Soil properties can be dynamic or inherent characteristics., go to Management.

Essential services provided by soil:

Soils support plant growth, recycle dead material, regulate and filter water flows, support buildings and roads, and provide habitat for many plants and animals. Depending on the land use, many of these functions occur simultaneously. Soil quality assessments go beyond measuring degradation (erosion, compaction, or contamination) to focus on these soil functions and the processes that create them. Go to Soil Functions for more information.

Soil meeting multiple and sometimes conflicting goals:

Soil functions provide private benefits such as crop production or structural support for buildings. Simultaneously, the same soil may provide societal benefits such as carbon sequestration, water quality protection, or preservation of soil productivity for future generations. Evaluating soil quality requires that we identify and prioritize these benefits and pay attention to the interactions and tradeoffs among them. Go to The Value of Soil for more information on the costs and benefits of soil quality changes.

Other definitions specify what functions a soil performs or how to quantify or measure soil quality. For more information, go to Published Soil Quality Definitions.

Resistance and resilience to disturbance as characteristics of a healthy soil:

The ability to continue providing essential services in the face of disturbanceAn ecosystem disturbance can be natural or human induced stress. An example of a natural disturbance is a hurricane or a tornado. An example of a human-induced disturbance is tillage or pesticide application., whether natural or human induced, is essential to maintain or improve soil quality over time. A soil is not considered "healthy" if it is managed for short term productivity at the expense of future degradation (Doran et al., 1994).

To learn more about resistanceAs a component of ecosystem stability, resistance is the ability of an ecosystem to remain stable in the face of disturbance. and resilienceAs a component of ecosystem stability, resilience is the ability of an ecosystem to recover after disturbance., go to Components of Ecosystem Stability. Stability is also a component of agroecosystem sustainability. Go to Soil Quality and Sustainable Agriculture to see how soil quality relates to ecosystemA functioning system of interacting parts of the physical environment and biological community in a geographic region. sustainability.

Doran, J.W., D.C. Coleman, D.F. Bezdicek, and B.A. Stewart. 1994. Defining Soil Quality for a Sustainable Environment. SSSA Spec. Publ. No. 35, Soil Sci. Soc. Am., Inc. and Am. Soc. Agron., Inc., Madison, WI.