Soil Testing: Properties, Growing Questions and Site Investigations

A Test Is a Particular Question About the Material

A chemical property and a physical property describe different aspects of soil. A request about a named substance is different again. A test group combines selected analyses, so its list of subjects is more informative than a broad name such as complete soil test.

For a grower, the interest may be the properties relevant to growing. For a buyer of delivered soil, it may be the characteristics of the supplied product. For a site investigator, it may be evidence relating to a specific environmental concern. None of those purposes automatically supplies the answer to the others.

Texture and Chemical Properties Are Different Subjects

Texture describes the proportions of sand, silt and clay. The USDA NRCS texture resource uses those three components to describe texture classes. A texture description therefore concerns the mineral particle mixture, rather than the quantity of a nutrient or a named contaminant.

Organic matter, pH and nutrients belong to other parts of the soil picture. NRCS identifies these among soil indicators, alongside physical and biological properties. A panel measuring some chemical characteristics does not become a texture assessment simply because both concern soil. The distinction helps a reader understand why two apparently similar soil reports can contain very different tables.

Laboratory Values Need a Material Identity

Results should remain connected to the sample and the area or product it represents. Soil sampling establishes that connection before analysis. A later reader needs to know whether the report describes an existing ground area, an imported material or another identified source.

For example, a report accompanying a soil delivery is most useful when the product identity can be followed into the order. A site investigation needs an equivalent connection between the test and the location under discussion.

Testing and Recommendations Are Different Stages

The laboratory measures selected subjects and records its findings. Interpretation explains those findings in relation to the intended use. A report may include both, or a separate adviser may provide the interpretation.

The soil analysis report guide explains how material references, values, units and comments work together. A recommendation should be traceable to the relevant evidence rather than appear as a general instruction detached from the analysed material.

When the Question Is Engineering or Contamination

Geotechnical investigation examines ground conditions for an engineering project. It is different from a growing-related test request. An environmental investigation may require analyses for specified contaminants and an interpretation of the site's history.

Soil testing laboratories can explain their analytical services. Describe the project purpose so the request is directed toward the right kind of information rather than an unrelated standard package.

Soil Testing Questions

Does a fertility report check every possible contaminant?

No. The report describes the subjects that were analysed. Contamination questions need an appropriate environmental investigation.

Can two soil reports have different test groups?

Yes. Compare the named properties and units before comparing the values. Different test groups may answer different questions.

What makes a report useful later?

A clear material identity and preserved analytical notes allow a later adviser to understand its purpose and decide whether it relates to a new question.