You’re right that Dr. Elaine Ingham (and Matt Slaughter Director of the Oregon Soil Foodweb Lab) are not recommending molasses in areated compost tea brewing. I hope its OK to write slightly long post to explain why no molasses in teas. While the results of compost tea around the world are incredible, and the general idea of making tea is accessible, like a lot of things the details, the details, the details…
One of THE KEY things to understand about the soil food web is its relation/impact to the above/below ground ecology succession pattern. From a microbiological standpoint, there are a wide range of soils and each type of soil supports or favors certain plant groupings. This is so very vital in understanding how to work with soil microbes. The succession pattern is primarily based on the mixture or ratio of bacterial biomass to fungal biomass in any given soil. The succession pattern is visualized as a continuum: on the far left you have disturbed desert like weedy soils and on the far right you have an intact healthy old growth forest. In between these outer edges you have starting from the left side a continual increase in biological complexity and diversity moving from annuals to perennials.
So, on the far left side of the succession pattern in a dry desert soil you’ll have a hard time finding visible fungi as fruiting mushrooms. These soils will typically have 8:1 bacteria to fungal ratios. Heavily bacterial dominated soils, alkaline (from bacterial secreted alkaline saccharides called slime) and Nitrogen cycled to plants in the form of Nitrate (NO3). “Weeds”, from a biological science perspective of pioneering annuals with mass seed production, love Nitrate. Now Move to the far right into the old growth conifer forest and you have a 1:100-1000 bacteria to fungal ratio. Fungi absolutely dominate in biomass in an old growth forest (think of Fungi guy Paul Stamets and where he lives in the old growth forest of the Pacific Northwet USA). The soil is slightly acid as fungi secrete acids during their externalized metabolic eating processes and the form of Nitrogen cycling in those soils is Ammonium (NH4). Trees like Nitrogen as NH4. Think of the continuum bacteria:fungi ratio looking like: 8:1______1:1________1:100-1000.
This succession pattern can evolve “forward” from left (degraded soils) to the right (ever increasing plant complexity, annual to perennials). ANything we want to grow exists somewhere along the succession pattern continum: (following the left to right succession pattern) our broccoli and cauliflower Brassicaceae; then our tomatoes, cucumbers, corn and rice; then small herbaceous plants; then vines like grapes; then fruit and nut trees; then conifers. As you move from the broccoli towards the tomotes and so on you get an EVER increasing amount of fungi biomass in the soil. If we walk away from a patch of soil and let nature grow what it wants, whatever the bacteria:fungi ratio is will favor certain groups of plants somewhere along the succession pattern continum. Dr. Ingham’s and the group of Soil Foodweb Labs around the world have amassed a lot of growing data over 20 years where they can pin point the ideal bacteria:fungi ratio of just about any plant we want to grow.
Disturbances drive the soil “backwards” or from right to left on the succession pattern. You get less fungal biomass, less perennials until it favors annuals, less humus and organic matter, less biological complexity above and below ground. Disturbances are: drought, flooding, fire, deforestation, overgrazing, compaction, inorganic fertilizers, fungicides, pesticides, plowing and tillage, (new research coming out showing) GMO plant and pesticide regimes, etc. I think its safe to say that most conventional industrial (and I would say a lot of ‘conventional organic’) agriculture is one big giant disturbance knocking the fungi out of the soil, pushing it “backwards” along the succession continuum and favoring plants that we might not want to grow.
Before brewing compost tea, the trick is to know what your current soil state is in terms of bacteria:fungi ratio and its relation to what plant groups you want to grow and then use actively aerated compost tea with either a bacterial dominance or fungal dominance to “nudge” the soil in the right direction. Bacterial or Fungal dominated tea??? Yes, in any biological system when a food for one organism is present that organism tends to do well. Molasses is bacterial food: anything that is a simple sugar like molasses, fruit juice, maple syrup, glucose, fructose bacteria LOVE. Also, high nitrogen content stuff like manure or legumes. Bacteria will thrive. Fungi, on the other hand, are made to digest complex carbon chains like cellulose or lignin (think woody material). Fungi can eat things like humid acid, kelp. Feed the tea these things and fungi generally thrive (depending on a bunch of other conditions but this gives us an idea).
So in our gardens or agricultural fields, yes even our ‘organic’ gardens (think putting natural non-chemical fungicide sulphur to control a powdery mildew outbreak doesn’t kill the good fungi as well? – all (in)organic fungicides kill both the good and the bad fungi but the bad guys repopulate typically more quickly) we tend to have degraded bacteria soil (not always but mostly). Because almost all cultivated soil that the Soil Foodweb Labs test is bacterial dominted (I’ve had a lot of agricultural soil here in Mexico tested and it confirms typical bacterial dominance) unless you want to grow Nitrate loving weeds you usually have to “nudge” the soil to more Fungal dominance. So you don’t put molasses in your teas because your soil usually already has enough bacteria – you want to focus on getting the fungi #s up.
