The Intricate Dance of Soil and Life

by | Jun 7, 2016 | Featured Slider, Latest, News

Life and soil are intricately inter-connected to each other in countless complex ways. When things are inter-connected a change in one element, or part, can affect the behaviour, structure or properties of the other. The inter-connections between soil and life means that a change in soil conditions can have a profound effect on Life in the vicinity, and the activities of living things also affect soil conditions. One could say Life creates soil, and soil supports Life.

These are some of the ways soil and Life are inter- connected:-

Life affects soil conditions and fertility.

Healthy soil is full of life. Estimates are that a square meter of healthy soil may contain a mind-boggling trillion (a million, million) or more microbes. A teaspoon of healthy soil may contain between 100 million to 1 billion bacteria. Many larger creatures such as insects, worms, nematodes, mammals also live in the soil and play a role in the soil eco-system. Life in the soil performs a range of important functions that affect soil conditions. Soil dwelling forms of life such as fungi, lichen, bacteria, microbes, fly larvae, beetles, termites, ants, millipedes and centipedes, worms, cockroaches and earwigs feed off organic waste and soil minerals and process these into soil nutrients that benefit plants.

Life in the soil affects plant and animal health and distribution

Soil life can alter soil fertility, soil texture, structure and acidity levels, affect the quality and quantity of nutrients plant roots absorb, change the way water and air circulate in the soil, improve soil stability, build humus, produce antibiotics that protect plants (and animals) against diseases and certain pests, and even decontaminates soils of certain dangerous toxins. All these factors affect plant health, and the type of plants that flourish in an area . Because certain animals often rely on particular plants for food, the species of plants found in an area influence what sort of animals are found there – and that affects plant life in the vicinity, which in turn can affect soil conditions. ( see also ).

Soil condition < > Plant Life < > Animal Life < > Soil Condition

Plants influence the behaviour of microbes around their root zones, and this influences plant health and soil conditions

Plants are not passive, inactive bystanders in the soil. Plant roots often give off certain carbon rich enzymes that stimulate certain microbes and fungi to become active around the plant root zone. These plant beneficial microbes feed on the enzymes extruded by the plant and play an important part in plant health. They help plants absorb nutrients, convert water insoluble soil minerals (such as sulphur, nitrogen and potassium) into water soluble nutrients that plant roots can easily absorb, alter soil conditions ( such as PH levels) to suit plants needs, provide protection against pests and diseases, and may release chemicals necessary for healthy plant growth, such as phosphorous. These armies of microbes also attract other beneficial creatures which feed off them, or off their wastes, and in turn also produce vital plant foods.

Many annual plants, for example, prefer their nitrogen as alkaline nitrate (NO3). These nitrate loving plants secrete root enzymes that actively attract nitrate producing bacteria to their root zones. Nitrifying bacteria change acid ammonium (a type of nitrogen) into NO3. Nitrogen in the form of NO3 is alkaline, so the partnership with nitrifying bacteria also increases soil alkalinity. Hardly surprisingly, nitrate loving plants also happen to prefer alkaline soil conditions. By partnering with nitrate producing microbes the plants can act to alter soil PH levels around their roots to suit their particular plant needs.

When a plant dies, or drops fruits, leaves or blooms, its nitrogen rich plant materials feed large numbers of fungi and bacteria that decompose organic matter. These decomposers absorb the stored plant nitrogen to fuel their own growth and reproduction. Their nitrogen rich bodies are then eaten by a host of soil dwelling predators and scavengers such as earthworms, protozoa and nematodes that release the concentrated nitrogen as ammonium (NH4), a form of slightly acidic nitrogen that many perennial plants thrive on. These perennial plants, not surprisingly, often prefer slightly acidic soil conditions and actively team up with special fungi, known as mycorrhizae, to maintain or increase levels of ammonium (NH4) in the soil. As levels of NH4 increase, soil conditions become more favourable for acid loving perennials such as trees and shrubs, and less hospitable for alkaline, nitrate loving annuals.

The partnership between plants and their preferred microbes thus plays a part in the way natural plant communities establish themselves. We can use this knowledge help us plan a sustainable garden eco-system over time ( Chapter 9 in An Ecological Gardeners Handbook. ( ) describes how to use plant succession to plan for sustainable plant communities.)

Of course, plants can only make use of beneficial plant microbes if the soil eco-system is healthy enough to support suitable numbers of the right sort of microbes.  The inter-connected relationship between soil and Life is the reason all organic soil management methods focus on creating conditions that promote flourishing soil life.

By Valerie Payne:

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