Brian Campbell
The Fungi-to-Bacteria Ratio
Updated: Feb 5, 2021

In the peer-reviewed Soil Biology Primer (Soil and Water Conservation Society, 2000), Dr. Elaine Ingham - who founded Soil Foodweb School - states that different successional stages have markedly different ratios of soil fungal biomass to soil bacterial biomass.
Healthy coniferous and old-growth forests exhibit soils with a very high fungi-to-bacteria ratio of at least 100-to-1. Healthy deciduous forests (pictured in background) exhibit soil with a fungi-to-bacteria ratio of at least 5-to-1. And a majority of our crops perform best in soils with a fungi-to-bacteria ratio of 1-to-1. If you're growing an early successional crop like canola (pictured in foreground), kale, or other brassicas, that have an evolutionary relationship to disturbed, bacterially dominated soils, you may want a fungi-to-bacteria ratio as low as 0.3-to-1.
Get your soil checkup today to see if your fungi-to-bacteria ratio is in the ballpark for your desired crop and whether the compost you're applying is pushing your soil to be more bacterially or fungally dominated.