The Soil Food Web
Modern farming damages Nature’s fertility solution:
The “Soil Food Web” describes the natural process that has evolved over millions of years to extract necessary nutrients from the base materials (rock, gravel, sand etc.) to allow plants to grow, providing the basis for the complex eco-systems that exist all over the world.
Over countless millions of years the same groups of microbes have filled the same niches in this web: bacteria, fungi, nematodes, protozoa and higher life-forms have done the same job in every ecosystem. Bacteria and fungi use enzymes to extract nutrients from the base materials (at the behest of the plants) that then are made available to these plants.
Plants manage this by releasing exudates (carbohydrates) through their root systems that indicate which specific nutrients they require. Some fungi (mycorrhizal fungi) form exchange sites with plant roots to swap these for the energy (carbohydrates) they need to thrive and grow; others, -and most bacteria, need to get eaten by predators before these nutrients are made available to the plants, so predators are also a vital part of the Soil Food Web (protozoa, nematodes, earthworms micro-arthropods etc.). The whole process is so complex that scientists completely missed it until relatively recently, which has led to the mistaken belief that all you needed to grow a crop was the right mix of NPK fertilizer! But it is obvious, when you think about it…
In a mature and stable environment, such as the Amazon jungle, there is nobody putting fertilisers on and spraying for pests, yet the fertility of the jungle is legendary. How does this happen? When settlers come in, clear-felling and burning to then plant commercial crops, these crops grow well at first, but then inevitably after 5-7 years the nutrients run out and the growers are forced to pay through the nose for fertilisers and pesticides or move on to the next piece of pristine jungle and destroy that! These crops fail because the intricate web of microorganisms that provided fertility for the original jungle was destroyed when they cleared the land. This pattern has been observed all around the world.
The Soil Food Web School videos:
- What is the Soil Food Web?
- Nutrient Cycling
- Why you need good Soil Structure
- Suppressing Pests and Diseases using the Soil Food Web
- Soil Carbon Sequestration and the Soil Food Web
Watch Dr. Elaine’s video or visit the Soil Food Web School for videos and farmer case studies.
Transforming Soil Health
Structure
In addition to this, fungi and bacteria are vital to the creation of structure in soil, which is crucial in keeping soil aerobic, assisting with both drainage and water retention. They produce glues when reproducing or growing, pulling soil particles together to create aggregates and airways thus creating healthy soil structure.
A healthy living soil creates humus, improving the fertility and health of the plants growing on it. Plant available nutrients are stored there, water and roots move easily through such soil and water is also stored more efficiently in these soils. Aerobic organisms (generally the ones you want in your soil) thrive in these structured soils, and anaerobic organisms (generally disease-causing and undesirable) are outcompeted and discouraged. These soils become more flood and drought resistant.
Variety is key
Using an olive tree as an example, to be fully engaged with its soil and fully provided for (as it has been since the days of the ancient Greeks), the soil will have a wide variety of fungi and bacteria living in its soil, with predators in sufficient numbers to ensure nutrient recycling. Many species of fungi and bacteria are geared up for extraction of only 1 or 2 of the desired nutrients, so a wide variety is needed to supply all of the olive tree’s needs.
Levels of Succession
As the land has been transformed from bare rock to lush forest the range of plants occupying each level changes. Lichens and mosses are all that can live on bare rock (the lowest level of succession), while after millions of years deeper soils and old growth forests occupy the highest level of succession. There is a direct correlation between the fungi:bacteria ratio in these levels of succession, with the low levels of succession being bacterially dominant and the higher levels being dominated by fungi.
Brassicas are bacterially dominant, whilst vineyards and orchards require more fungi in the mix… so the right balance of the F:B ratio depends upon your crop. Even the saguaro cacti of the Sonoran Desert are considered old growth forests for their ecosystem and are found to have soils that are fungal dominant.