Soil Quality: Is it the Future Direction for Agricultural Sustainability and Environmental Quality?

 

The protection of the soil, one of our most precious, non-renewable, resources, is gaining much attention from farmers, the scientific community, and the general population as it is becoming apparent that the ability of soil for self-cleansing is not unlimited. Soil quality is arising as an environmental issue as important as the quality of the air we breathe and the water we drink.

¡°Soil quality is an environmental issue as important as the quality of the air we breathe and the water we drink.¡±

Soil is a vital natural resource that is non-renewable on the human time scale; it is a living, dynamic, natural body that plays many key roles in terrestrial ecosystems.  The soil is a rich mix of mineral particles, organic matter, water, gases, and nutrients.  Dan Hillel, a retired professor from UMass, stated when optimally filled with vital water, soil constitutes a fertile substrate for the initiation and maintenance of life. It is the essence of life and health for the well being of humankind and animals.  Soil is the major source of most of our food production, and its health is essential for sustained productivity of food.  Scientists and lay persons have long recognized that the quality of air and water natural resources can be degraded by human activities.

The soil was once believed to be self cleansing, but this perception is only partially true. It is now recognized that the quality of soil can also be affected by different land use systems. The soil acts as the earth's primary cleansing and recycling medium, in effect as a "living filter", where pathogens and toxins that might otherwise foul our environment are rendered harmless and transmuted into nutrients. Soils also serve as an essential reservoir of water for terrestrial plants and microorganisms and play an important role as a purifying medium through which water passes.

Soil quality or productivity can be affected by the type of farming and agricultural practices. Many agricultural activities have a negative impact on soil biological, physical, and chemical properties and can deteriorate soil quality. This deterioration in soil quality is due to loss of organic matter and results in soil erosion, acidification, salinization, nutrient deficiencies from monocropping, and poor drainage. Sometimes deterioration is a result of continuous use of unsustainable and improper land management systems. In an organic farming situation, soils will normally build up organic matter over the years. Undisturbed soils under pasture system will have different soil quality compared to that under organic farming or a conventional system.

Soil quality is defined by many scientists in different ways however, the focal point remains similar.   Health or quality of a soil has been defined as the ability of soil to support crop growth, including factors such as tilth, aggregation, organic matter content, soil depth, water holding capacity, infiltration rate, pH changes, and nutrient capacity. Doran and Parking, researchers at Iowa State Univ., defined soil quality as the capacity of a soil to function within ecosystem boundaries to sustain biological productivity, maintain environmental quality, and promote plant and animal health. The important parameters used to assess soil quality are broad and include physical, chemical, and biological parameters as well as descriptive variables. Many soil physical, chemical, and biological properties are a function of soil organic matter content.  The quantity and quality of soil organic matter that is present under organic, pasture, and conventional systems would vary greatly and influence other soil properties significantly.

Soil organic matter is the key for maintaining or improving soil quality because it exerts a profound influence on nearly every facet of the nature of soil. However, information on the impact of various agricultural practices on soil quality and soil organic matter in particular is not available to researchers or farmers, the primary stewards of soil. As a result, there is a need for us (farmers and researchers) to work together to identify the effectiveness of different agricultural management options to maintain or to improve soil quality by soil organic matter management.

 

Jay Daliparthy and Stephen J. Herbert

Dept. of Plant and Soil Sciences

University of Massachusetts Amherst

Crops, Dairy, Livestock News. Vol. 2:1, Spring 1997

 




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