Article for Bangalow 0015
Part I: Soil Biodiversity
For the series of article on biodiversity I thought I‘d start with what is after all the basis of
garden life, the soil.
We all know that through the soil plants have access to nutrients, what is much too often
overlooked is the role of the microbial communities in nutrient and carbon cycling and the
relationship of these micro-organisms have with themselves and the plant kingdom, both
below and above ground. This is often referred to as soil food webs. Studies done in Europe
are showing that there is important correlation between soil organisms and the workings of
ecosystems.
To simplify, I will describe the action of 4 of the major players of soil organisms.
Bacteria: they are responsible for the largest chemical soil transformation of any group of
organisms and underpin soil health.
Eukaryotes: they fix carbon and breaking down complex organic matter. They also affect the
physical nature of the soil ecosystem.
Invertebrates: they are soil engineers. They provide the soil with access for water and air,
providing the two elements necessary to biogeochemical reactions. They do this by
burrowing, drilling, mixing and processing the soil. Some harvest organic matter and build
compost heaps in their nests and burrows, inoculating them with fungi to break down plant
matter.
Insects and spiders: By drilling in the soil to create nests and burrows they increase the
chances for water infiltration into the plants root zones and slow down water runoff and
reduce soil mineral loss, mostly nitrogen.
How to preserve and increase soil biodiversity?
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Keep soil disturbance to the minimum. In garden like in agriculture, excessive tillage
degrade the soil organisms environment
Avoid the use of herbicide and pesticide.
Control your fertilizer use. To have healthy soil biology it is important to understand
the importance of Carbon/Nitrogen (C/N) balance.
The efficiency of fertilizer use will be high where the organic matter content of the
soil is also high.
Plant diversity has a beneficial effect on soil food web, although this is not yet fully
understood it seems that the relation of root biomass and soil biodiversity is of the
upmost importance
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Mulching protects and keeps the top soil from drying out; this is beneficial to soil
micro organisms. If your soil is low in worms and other invertebrates I would
recommend using Barley or soy bean mulch as the results are simply stunning.
Advantage of a healthy soil
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Retention of nutrients due to reduction in leaching
Nutrients are more easily available to plants
Development of deep root system that will reduce water and fertilizer use and
increase plant growth
Balance soil biology will decrease risk of disease
Soil biodiversity is very important and affect not only plants but the ability of soils to
regulate the flow and storage of water, maintenance of the soil structure, reduction in
pest and diseases.
The soil bacteria play a vital role in detoxification of pollutants and regulation of our
planet atmospheric composition.
To give a perspective, soil is estimated to contain one quarter to one third of all living
organisms on planet Earth.
For further reading go on www.facebook.com/Interactive.landscapes where I have
posted my reference sources
Patrick Regnault Registered Horticulturist MAIH