How to Interpret Soil Foodweb Assays

Review your report carefully

Soil Foodweb assays assess the interaction of a large number of possible organism groups and their interactions in soil. The information obtained can be used to finely tune what is going on in soil, and what needs to be done to bring the soil back to a condition of health. There are many things to consider, however, so go through your report carefully, step by step.

On the Soil Foodweb report, note the bottom line of the table, which says "Desired Range". This indicates the Minimum desired range for each assay, based on previous testing done through the years by Soil Foodweb Inc. The only exception to this rule is ciliates (see section on protozoa, below)

The desired values can be different based on plant type, soil type, climate, season, etc. Of course, these values are based on plant growth when pesticides and other inorganic and toxic materials are not required to maintain healthy plant growth.
The values in the desired range row were determined based on years of collecting data about the biology in healthy conditions, when plant growth is optimal. The desired range therefore, changes based on plant, season, climate, soil, and on our ever-increasing knowledge base.

If the soil is not in healthy condition for a particular plant, then those plants will be stressed. It may not be incorrect biology, however, that is the sole reason for stress. If the soil is lacking in a nutrient, the biology cannot do anything to make available a real lack of a chemical. In this case, the nutrient will have to be added to the soil, but preferably in a biologically available form. Often soil organisms can solubilize not-plant-available nutrients and make them plant-available. To hold, and retain, nutrients, organisms may be required to act and turn nutrients into non-leachable forms. Such is the case with nitrogen – the inorganic forms are highly leachable, while the organic forms are not subject to significant leaching losses.

When the biology is lacking, after use of chemical pesticides, or high levels of N, for example, addition of inorganic nutrients be required until the numbers and balance of the different organisms can be improved.

Soil physics may have to be improved as well, and it is the organisms that build soil structure. Physics (soil aggregate structure), chemistry, and biology work together. It is silly to talk about any one of them being "most important": soil biology, soil chemistry and soil physics all have to be optimal for the chosen plants in order for the plants to grow well.

Use the following information to allow you to interpret what to do if the biomass of your food web organisms is too low, too high, or "just right".

Steps 1 & 2