An extract from our latest publication, Make Compost, Not Work – gardening columns from the Idler available here

The Symphony of the Soil

Spring is on the way, and the earth is beginning to warm up and come to life once again. In a well-balanced living organic garden, our tomatoes, beans, chard and apple trees thrive in an active and vibrant ecosystem, and at it’s heart is the soil. The mineral content of the soil and its physical structure are of course important, but it is the life in the earth that powers its cycles and provides fertility. This is the reason why mindful gardeners will always feed the soil rather than their plants. The soil biota includes;

• Megafauna; large animals such as moles, rabbits and rodents.
• Macrofauna; For example woodlice, ants, spiders, earthworms, beetles, centipedes, slugs, snails, ants, etc.
• Mesofauna; Life ranging from two mm to 100 millimicrons, like mites and springtails.
• Microfauna and Microflora; Microscopic life such as yeasts, bacteria, fungi, nematodes, protozoa, rotifers, etc.

These humble denizens of the earth are often under-appreciated or even regarded negatively as “pests” by the uninformed. Yet they are vitally important – without their activities, dead matter would accumulate and litter the soil surface, and there would be no food for the plants upon which everything else depends. So let’s focus on a few of the star players in this symphony of the soil system…

Earthworms

Earthworms are essential to composting; the process of converting dead organic matter into rich humus, a medium vital to the growth of healthy plants. This is achieved by the actions of the worm as it pulls down below any organic matter deposited on the soil surface for food. Once in the burrow, the worm will shred the leaf and partially digest it, then mingle it with the earth by saturating it with intestinal secretions. Studies have shown that earthworms can increase fertility and yields by as much as 25 per cent.

Bacteria

Bacteria are single-celled organisms and are the most numerous denizens of the soil, with populations ranging from 100 million to three billion in a gram. They are capable of very rapid reproduction by binary fission (dividing into two) with one bacteria capable of producing 16 million more in just 24 hours. Bacteria are essential for transforming nitrogen from decomposing organic matter into food available to growing plants. Rhizobial bacteria live in close symbiosis with leguminous plants like peas and beans, forming colonies in root nodules that can “fix” nitrogen from the atmosphere.

Fungi

A gram of garden soil can contain around one million fungi, yeasts and moulds. Fungi are not members of the plant or animal kingdoms but constitute a separate classification. Unlike plants, fungi have no chlorophyll, and cannot photosynthesise. Thus, like us, they require an external source of carbohydrates for energy rather than being able to produce their own from water, carbon dioxide and sunlight. They spread by sending long thin mycelial threads throughout the soil, many living on dead or decaying organic matter, breaking it down and converting it to forms available to plant roots. Mycorrhizal fungi, sometimes known as “nature’s internet” due to the beneficial soil connections they create below the ground, live symbiotically with living plants, forming relationships advantageous to both. Plant root hairs are penetrated by mycelia that enable the fungus to obtain the carbohydrates it requires. In return they provide the plant with nutrients including nitrogen and phosphorous, and moisture otherwise beyond its reach.

Actinomycetes

These microbes are a cross between fungi and bacteria, and after these are the most numerous soil organisms. They are also critical in the decomposition processes of organic matter and humus formation. Their presence causes the sweet earthy “fresh woodland” aroma associated with good healthy earth, as well as the scent of petrichor when they become activated following rainfall on a hot summer’s day after a prolonged dry spell.

Thanks to the Hubble telescope, we know more about galaxies millions of light years away than we do about the interactions between the soil life beneath our feet. But by adopting mindful observation and treating it with respect, minimising practices like digging or using toxic chemicals, we can all strengthen our relationship with this most precious of resources in our own back gardens or allotments.

Graham Burnett. First published in the Idler issue 54

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