Soil Assessments

Soils are a complex system of physical, chemical and biological components. The blend of sand, silt, clay and organic matter influences the ability of the soil to serve as a reservoir and supplier of water and nutrients. How these soil components are bound together into soil aggregates is important for the movement of water and air into and through the soil. Soil organic matter, exudates from roots, excrements from macro/microorganisms and fungal mycelium enhance soil aggregation. Visual inspection and the feel of a shovel full of soil can provide a general assessment of the physical nature and quality of soil. Strong soil aggregates are an indicator of good soil quality. Weak aggregates that are easily crushed are not. The ease with which a shovel or spade full of soil can be dug provides a measure of soil quality. Feel of the soil relates to its physical composition, but can provide some indication of other properties. Sandy soils (gritty) have less capacity to hold and supply water and nutrients than do loamy (smooth) and clayey (sticky) soils.

Quality of the soil chemistry is best determined in a soil testing lab. Soil pH, organic matter content and available nutrient levels are indicators of soil chemistry quality. Total carbon and nitrogen contents relate to overall soil quality. Soil pH is a key measure of soil chemistry quality as it affects overall plant growth, microbial activity and composition as well as the availability of the essential elements to plant roots. When the soil is too acidic soil testing labs can determine how much lime is needed to bring the soil pH to a favorable level. Soil organic matter is the key modifier and buffer of soil quality. These soil testing services are available from numerous private soil testing laboratories as well as from the Michigan State University Soil and Plant Nutrient Laboratory.

The biological composition and activity of soil is a good indicator of soil health, but assessment of these are time consuming and somewhat pricey. These assessments are available from a few specialized labs. Determination of nematode diversity is available through the MSU Nematology Lab associated with the MSU Plant Diagnostic Center.