Since there is a thread on soil testing, I thought it responsible to talk a little about biological or microbial testing.
This was once again brought to my attention the other day when I was asked to review some test results. As with my recommendations for nutrient testing, if you want formal results then deal with an accredited lab. They will be able to give species to a degree and numbers,
The work can be done informally with direct microscopy and extended cultures, as I do but be certain the microscopist knows what they are doing. Watch out for results given in units of measure of mass per volume (eg. micrograms per milliliter) without provision of the foundational information estimating the weight of bacteria or fungi. If diverse species are lumped together, the results can be highly skewed simply because different species have different densities (mass).
My preference is an expression of percentage of volume being occupied by the target microorganism. eg. 10% of viewed sample was fungal or bacterial biomass. OR numbers of microorganisms per ml or cm3. Even better may be showing results via video.
Also be wary of statements that a certain ratio of microorganisms will result in a provision of 'X' amount of nitrogen (etc) per given area or volume (eg. per acre) unless you understand and agree with the foundational substantiation provided.
If a count of amoebae is provided it should show a clear separation of testate and naked amoebae. Naked amoebae cycle nutrients more rapidly.
A high count of bacterial feeding nematodes is a very good indicator of fertile soil. This factor is often overlooked in biological testing.
This was once again brought to my attention the other day when I was asked to review some test results. As with my recommendations for nutrient testing, if you want formal results then deal with an accredited lab. They will be able to give species to a degree and numbers,
The work can be done informally with direct microscopy and extended cultures, as I do but be certain the microscopist knows what they are doing. Watch out for results given in units of measure of mass per volume (eg. micrograms per milliliter) without provision of the foundational information estimating the weight of bacteria or fungi. If diverse species are lumped together, the results can be highly skewed simply because different species have different densities (mass).
My preference is an expression of percentage of volume being occupied by the target microorganism. eg. 10% of viewed sample was fungal or bacterial biomass. OR numbers of microorganisms per ml or cm3. Even better may be showing results via video.
Also be wary of statements that a certain ratio of microorganisms will result in a provision of 'X' amount of nitrogen (etc) per given area or volume (eg. per acre) unless you understand and agree with the foundational substantiation provided.
If a count of amoebae is provided it should show a clear separation of testate and naked amoebae. Naked amoebae cycle nutrients more rapidly.
A high count of bacterial feeding nematodes is a very good indicator of fertile soil. This factor is often overlooked in biological testing.
