Those of us with some basic understanding of organic principles for growing food are aware that it is the interaction of the microbiology in the soil which produces fertility. We, (or other animals) add organic matter, and the biology in the soil break it down; one microbe eats some of the organic matter, who in-turn gets eaten by a larger organism ad infinitum each going through their respective lifecycles. This is the widely held view, but a more detailed understanding is emerging with the help of microbiologists like Elaine Ingham and her Soil Foodweb
In March 2019 I signed up to the Soil Foodweb’s Foundation Course which introduces us to the world of microorganisms that were once in every living soil on the planet. We’re learning how plants exchange nutrients – exudates – with microorganisms that populate healthy living soils; and how nature has been growing plants & trees successfully without any chemicals or artificial fertilisers for millions of years!
When the Soil Food Web is in place plants are continually given access to abundant nutrients held in the mineral particles of the soil itself as well as in the organic matter. It is the plants themselves who feed and breed an army of microorganisms in the root-zone (Rizosphere) providing the plant with any nutrient it requires – on demand! There is no better way to grow plants than the way Nature herself has devised. Plants & trees are in full control of the army of microbes that they command which nourish and protect plants from diseases and pest organisms. Restoring the Soil Food Web is the essence of all soil restoration practises and is the foundation of Soil Carbon Sequestration.
Plants absorb carbon from the atmosphere during photosynthesis and they invest a substantial proportion of this into the soil as simple sugars, to feed microorganisms. This is the basis of the mechanism that pumps carbon into the world’s soils.
It has been estimated that by regenerating the world’s soils using the Soil Food Web we could reverse climate change within 5 years.
The Members of the Soil Food Web
BACTERIA are defined as three types:
- Aerobic – Good guys
- Facultative – Good & bad guys, ie can be aerobic or anaerobic (most human pathogens come from this type of bacteria)
- Anaerobic – Bad guys, (their presence indicates anaerobic conditions detrimental to good guys. They produce alcohols detrimental to plants)
FUNGI are defined as three types:
- Saprophytic – Beneficial, (breaking down organic matter)
- Mycorrhizal – Beneficial to most plants. Live in a living host plant
- Oomycetes – Disease causing
PROTOZOA three main types:
- Flagellates – Good guys, prey on bacteria, (releasing nutrients in plant available form)
- Amoebae – Good guys, prey on bacteria, (releasing nutrients in plant available form)
- Ciliates – Bad guys, prey on bacteria, (but indicate anaerobic conditions)
NEMATODES four main types:
- Bacterial feeding – Good guys, (releasing nutrients in plant available form)
- Fungal feeding – Bad guys (as we’re trying to increase fungal biomass)
- Predatory – Good & bad, (depends who the prey is)
- Root feeding – Bad guys in large numbers (killing or weakening our plants)
- Mini insects, spiders & crustaceans
- Larger insects, spiders & crustaceans
When this Soil Food Web is out of balance, ie predator populations drop sharply, this increases the possibility of subsequent pest outbreaks. Tilling the soil & adding pesticides have enormous detrimental effects on non-target species.
Fungal to Bacterial Ratio & Succession
One of the most beneficial members of this earth community are fungi, apart from their fruiting bodies, (toadstools) fungi have literally miles of fine microscopic fibres called hyphae running through the soil which are destroyed each time we turn the soil. The benefits of this network of fibres is only recently becoming known.
- Fungi can break-down complex carbon material which bacteria cannot cope with.
- They can transport nutrients large distances
- They can have mutually beneficial relationships with plants
- The outer sheath of the hyphae running through the soil is high in carbon, so increasing the carbon content of the soil even when fungi dies
Elaine Ingham teaches that there is a natural succession within soil which goes from bare parent material, (soil/dirt) through a variety of successions cumulating in conifer, old growth forests. This succession is marked by increases in the Fungal to Bacterial Ratio.
What this means in effect is that we can choose the stage of succession we want to grow particular types of crops, and increase beneficial fungi by adding BioComplete compost. We only need to add small amounts because we are inoculating the soil with life forms which will multiply – additionally we must stop tilling the soil.
Elaine advocates particular ratios of materials used to create BioComplete compost based on extensive research of the needs of microorganisms in the soil. The basic ‘recipe’ is:
- 60% browns
- 30% greens
- 10% high nitrogen
The idea is to create ‘hot heaps’ combining the materials at 50% moisture while allowing sufficient air into the heap, giving the ideal conditions for the microorganisms to multiply. This increase in aerobic organisms multiplying creates the heat which, once above 55C kills pathogens & weed seeds. The temperature needs to be maintained above 55C for three days, then turning the heap to replace the outer material into the centre to ‘cook’ for another three days, turning once more and leaving for another three days above 55C. By this time all parts of the heap will have reached over 55C for three days, theoretically.
Though this sounds simple enough there are problems:
- the heap should not go above 65C, if it does a different set of microorganisms kick-in, anaerobic organisms. If the heap goes above 65C there is a risk of it catching fire as alcohol is produced which has the potential to spontaneously combust. Alcohol is also poisonous to plants.
- on the other hand it is difficult to maintain temperature above 55C for the prescribed period, as heat is lost with each turn
- 50% moisture must be maintained during the process
- if air circulation is lost, this promotes increases in anaerobic organisms
Once this process is completed the pile should be left to reach ambient temperature, then moved to a storage area to mature, ensuring moisture levels remain around 40%.
Using a Microscope
During this maturing stage a microscope is used to check that the heap can be classed as BioComplete, ie it has the prescribed organisms present in sufficient numbers.
BioComplete Compost Extract
Once we have BioComplete Compost we can create compost extract which has some of the beneficial microorganisms within it. This can be used as a soil drench/injection putting organisms back into depleted soil.
BioComplete Compost Tea
Compost tea consists of Extract to which microbial food is added to increase numbers of organisms. Air must be pumped through the liquid to ensure it is the beneficial aerobic organisms which are being produced. Tea is used to disperse organisms onto above ground surfaces of plants & trees where they will stick using glues they produce in the process.
If when using the microscope we find that the compost is deficient in one or more types of organisms, all is not lost. There are a number of methods which I won’t go into now that can be used to produce particular types of organisms, these can be added to the compost to bring it up to the required standard. The purpose of compost tea is to cover microscopic pores on leaves, which if left uncovered allow diseases into the plant.
As mentioned above digging-up the soil kills much of this soil life, but as we know, if we leave bare soil Mother Nature responds by selecting pioneer plants to re-cover the soil. We, call these plants weeds because we have no use for them and they crowd out the plants we wish to grow.
So to align with natural practices we need to help Mother Nature to cover her soil with low growing plants, preferably perennial ones, the more diverse the better, which will stay alive over the winter re-growing each spring. We need to sow our chosen plants into this low-growing sward. The benefits of doing this is that the soil food web is in place all year round, ready to attach to the growing roots of our crop plants, increasing our yields.
No Dig/Sheet Mulching
Not actually learnt from the Soil Foodweb, but a Permaculture practice on smaller scales is No Dig. Related to No Till, in this process an area of land is covered with cardboard, with an initial 100mm – 150mm application of compost added to it. The cardboard helps cut-out the light & heat of the Sun and forms a barrier for more pernicious weeds, the whole decreasing the growth of weed seeds that are in the soil seed bank.
We plant our chosen crops directly into the compost, allowing the roots to find the soil beneath.
The main benefits of this process are:
- the soil is not disturbed, allowing the Soil Foodweb to establish
- the addition of compost (preferably BioComplete Compost) feeds the microorganisms, adding organic matter (and so carbon) to the soil as the worms & microorganisms draw it down into the soil
- keeping the soil covered this way saves water from evaporating from the soil surface
- the immediate surface of the compost drys out limiting the chance of weed seeds blow in by the wind from germinating, those that do can be more easily pulled out of the loose compost structure
So that brings us to the end of this introduction to the Soil Food Web. These are the practices & processes we will be using in future at this garden. Though in its infancy the Soil Foodweb approach has the potential to grow exponentially as more people come to the realisation that the reductionist, mechanistic old ways of doing things are being superseded by the new science of systemic thinking, where humans realise once more, that to benefit from the complex system that is Nature, we must understand & work with it rather than try to dominate it.
We have followed the ‘old story’ for so long that our life-support system is very close to collapse; we now need to focus on regenerating our life support system. We need to create a Regenerative Culture.
We are the ones we’ve been waiting for.
If you’re interested “like” the Facebook Page so that you’ll be informed about future events.