When we are looking to restore life to the soil, our most important tool is compost.  But not just any compost.  To increase diversity and restore missing groups of plant-beneficial organisms, we need to create an effective inoculum of these microbes.  You could think of the inoculum aspect a bit like a yogurt culture or a sourdough starter for the soil, although fermentation itself doesn’t appear anywhere in our process. 

For a sizeable (and usually quick) response in nutrient cycling, soil structure, pest/disease/weed control and water retention, we use compost that is “biologically complete”, meaning that it meets minimum standards for the amount of plant-beneficial bacteria, fungi, protozoa and nematodes present per gram.  Making this gold-standard compost is both an art and a science, and feels so rewarding!  Key aspects include:

Starting Materials

This is what the organisms come in on, what they will feed on, and what will continue to attract air-borne organisms to your finished pile.  Most soils are lacking in fungi, not bacteria, and so a balanced recipe that is rich in fungal foods is our goal.

Temperature

Our aim is for the pile to get hot enough for just long enough that the pathogenic organisms are knocked back, yet not so hot that the plant-beneficial organisms are killed too.  We will never deal with all the pathogens – our goal is to create an aerobic environment where plant-beneficial soil organisms can out-compete any pathogens that may have escaped the heating process or settled into the pile afterward. 

Turning

We want assurance that every part of the pile has reached (but not exceeded) the desired temperature range.  With a well-calculated recipe, all parts of the pile can move through this hot stage with just three turns.  Turning the pile affects the fungi, so the least number of turns, the better.

Moisture

Soil organisms need a specific moisture range.  As moisture gets too high, oxygen goes down, causing anaerobic conditions that will allow pathogens to flourish.  As moisture gets too low, plant-beneficial organisms will either die or go dormant and the decomposition process will stop.

I’ll be covering these aspects (and many more) in detail in my fall workshop series.  Look for Introduction to Soil Biology Part 1 in the CVRD Recreation Guide, Wednesday evenings November 7-21. To register please call Cowichan Community Centre at 250.748.7529