Soils are vast and complex living ecosystems, teaming with an incredible diversity of micro and macro-organisms that function together as one superorganism. The diversity of life that exists within the soil environment perform an array of crucial functions including decomposing organic materials; mineralisation of soil nutrients; fixing atmospheric nitrogen; enhancing soil aggregation and porosity; building soil humus; preying on crop pests and being consumed themselves by higher level predators from the intertwined soil food web.
The soil food web
Within the soil ecosystem, there are six main types of organism; bacteria, fungi, protozoa, nematodes, insects and earthworms. It is through the interaction of these organisms that highly productive natural soil ecosystems can maintain their fertility without the application of fertiliser year after year. Optimising these natural processes of nutrient cycling to supply our food crops is of key interest for low input, agroecological production methods such as permaculture.
The soil food web offers a perfect example of the permaculture viewpoint regarding collaboration and synergy whereby the whole is greater than the sum of its parts. The focus is on the relationships between organisms and how they function as a whole system.
Feeding your soil organisms
Soil biology is the most complicated living system we know about, but as growers we do not need to fully understand it. Just by looking at soil, smelling it and feeling it, you can see that living soil looks very different to dead soil.
What we do need to know is how best to support soil life: For the bacteria, feed fresh, green matter. For the fungi, provide lots of brown carbon (e.g. straw, leaf litter), avoid disturbing the soil, and prevent excess moisture. For the worms and insects, provide bulky organics and drill the soil occasionally. For all soil life, keep tillage to a minimum, avoid compaction, keep the soil covered with living plants or mulch, avoid excess soluble nutrients and avoid pesticides.
This page is based on a talk given by soil consultant Joel Williams at the International Permaculture Convergence 2015.
This content is derived from work created within the GROW Observatory, which received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 690199.