Assessing Soil Quality

Soil quality, often referred to as soil health, is a topic that continues to receive much attention.  As producers continue to push for greater yields and improved economics in their crop production system, more emphasis is being placed on the soil environment and its ability to produce a healthy crop in a sustainable way.  However, evaluating soil quality is not always as simple as pulling a soil sample and sending it to the lab.

The USDA-NRCS defines soil quality as “the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans”.  As evidenced by this definition, there is no one set parameter by which one measures soil quality.  The term can be interpreted in a number of ways depending on the situation.  Different soils in different locations will have different forms of “quality”, so the producer must learn to understand the capabilities of their soil and temper their expectations according to that capability.

One of the most fundamental steps to take when evaluating and managing for soil quality is to understand the soil that you are working with. Some properties of the soil cannot be practically changed.  These properties, known as inherent soil properties, are a result of how the soil was formed.  One example of this is soil texture.  A sandy soil will, for all practical purposes, always be a sandy soil.  Short of incorporating a huge amount of silt or clay, there is nothing you can do to change this. Massive changes like this can also result in negative impacts on the soil. However, there are other soil properties that can be influenced somewhat by management.  These properties, known as dynamic soil properties, can be influenced by how the soil is managed.  For example, soil organic matter content is a dynamic soil property.  It can change, however slowly, by how you manage tillage and crop residues. Soil structure can also be improved through proper soil management, again these changes take years to have a significant positive impact.

 A number of different assessments should be made, including a thorough examination of the physical properties of the soil. While soil health testing methods are being developed, these are not standardized today and interpretation of results still require validation. In addition, a standard soil test is also an important way to evaluate the chemical properties of the soil to ensure that nutrient levels are appropriate for growth.