What data are on the analysis report of Soil Life Monitor?

Microbial biomass

Total microorganisms (sum of the number of bacteria, fungi and protozoa). 

  1. Total bacteria – Certain groups of bacteria break down (simple) organic material, fix nutrients, bind atmospheric nitrogen, convert ammonium into nitrate nitrogen, form stable aggregates, increase disease resistance, and form breakdown products that can weaken or kill pathogens. Bacteria are stimulated by easily degradable materials with a low C/N ratio, such as slurry. Gram(+) bacteria - Bacteria that are more resistant to drought. Actinomycetes - Specific group of gram-positive bacteria, important for soil resilience. Gram(-) bacteria - Bacteria that are more resistant to stress, such as ploughing and pesticide use.
  2. Total fungi - Fungi cause complex forms of organic material to degrade, form stable aggregates, and excrete organic acids which improve the availability of some nutrients and increase disease resistance through competition or predation. Fungi are stimulated by recalcitrant materials with a high C/N ratio, such as straw and compost. Mycorrhiza - Group of fungi that cohabit with plant roots. In exchange for sugar, the plant receives water and nutrients (P and K). Saprophytes - The remaining fungi.
  3. Protozoa - Single-cell microorganisms that contain a cell nucleus (eukaryotes). The most important function of protozoa is to make nutrients available to the plant by "grazing" on microorganisms (mainly bacteria). The activity of protozoa is highly dependent on the presence of moisture in the soil. The radius of action of protozoa is limited to water films and water-filled pores.

Diversity index (Shannon-Wiener index)

The PLFA diversity (Shannon - Wiener index) is an indicator of the diversity of soil life. However, the diversity of the PLFAs is not the same as actual diversity because one unique phospholipid fatty acid does not represent one species. Higher diversity is often related to better stability and resilience. Disturbances, lack of diverse input from food sources, and an intensive crop rotation can decrease the diversity.

Fungal-to-bacterial ratio

The fungi/bacteria ratio indicates the proportion of fungal and bacterial biomass (expressed in mg C / kg). In general, undisturbed ecosystems have a higher fungi/bacteria ratio than disturbed systems. Organic and low-input systems have a higher fungi/bacteria ratio compared to enriched conventional systems. Disturbances such as tillage and the removal of crop residues can lower the fungi/bacteria ratio.

Gram(+)/Gram(-) ratio

Gram(+) bacteria are generally larger than Gram(-) bacteria and can form spores. This makes them more resistant to drought and water stress. Gram(+) dominant populations (>1) are more common at the start of the growing season and typically move to a more balanced community when the soil conditions become more favourable throughout the growing season. Gram(-) dominant populations (<1) are often associated with other forms of stress, such as ploughing and pesticide use. Gram(-) bacteria can better tolerate these forms of disturbance due to the presence of an outer membrane. In addition to the biological key figures, several physical soil key figures are also presented, namely 1) pH 2) organic matter and 3) clay. The ratings on the report are largely intertwined with organic matter content because higher organic matter contents are expected to have greater microbial biomass than lower organic matter contents. Both microbial biomass and bacteria and fungi are expressed not only as mg PLFA per kilogram, but also as mg carbon (C) per kilogram.

Soil Life Monitor report