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