Page 32 - Simply Veg Issue 1 2016

The Soil Association
often mentions that the way to a good fertile soil
is to encourage bene cial soil organisms and I will cover some methods of doing this here. The rst
thing is to create a favourable environment in the soil for these soil organisms. This
will improve plant growth and reduces the amount of garden maintenance required
to maintain your garden and allotment. Encouraging soil organism is central to building a healthy fertile soil, supportive of optimum plant growth and this is one of the main theories of organic gardening; the so called muck and mystery. So how do we go about creating this perfect environment in the soil?
1. Add organic matter to the soil, apply as much as you can spare to your cultivated areas. Soil organisms require a food source from soil amendments (compost, crop residues) and / or mulch. The organisms feed on the organic matter and some live within it. As they feed on the organic matter they break it down and release the nutrients and other useful compounds within it. Once the organic matter is partly broken down it becomes humus and other bacteria and soil fauna live and feed on this which releases further materials that help to improve the soil structure and soil environment. Any organic matter will improve the soil once the bacteria and other soil organisms break it down, such materials as manure from farm animals, leaf mould, spent mushroom compost, spent hops, rotted wood chip or basically anything that has once lived.
2. Use an organic mulch, this stabilises soil moisture levels and temperature as it acts
as an insulator which traps the warmth
in during the winter and reduces the
heat from the sun in the summer. It also reduces evaporation of water from the soil during the summer months which reduces the amount of watering that is required. And using an organic mulch adds organic matter as it breaks down and the worms take it down into the soil. Mulches may help prevent soil compaction and protect soil oxygen levels needed by soil organism and roots. On sloping sites it also helps to prevent soil erosion which has become a severe problem in some parts of the world during heavy rainfall. Organic mulches also look more attractive than bare soil weeds or plastic mulches.
3. Water effectively, by this I mean applying the right amount of water at the right time. Do not over
water as this is
herbicides are harmful to various types of soil organisms. I use compost tea as far as practical as this boosts the health of the soil and plants and reduces the need to spray for pest and disease control. Because we (the midlands) have the allium leaf miner then I have to spray all my alliums I have no choice otherwise the crop would be decimated. If anyone knows of an organic cure for the allium leaf miner please let me know.
6. Avoid using plastic sheets as a mulch as this practice discourages microorganisms activity by reducing water and air movement into the soil. I use a weed suppressant (from Wilko) this allows
air and moisture to get into the soil but prevents weed growth and helps to keep the soil slightly warmer.
Soil Fertility
by Mick Poultney FNVS
just a waste of
water (a valuable
resource), but
do not allow the
soil to dry out too
much otherwise
the soil organisms will shut down and go into a type of suspended animation. Soil organisms require an environment that is damp but not soggy, between 50°f - 90°f. Soil organism activity may be reduced due to the dry soil conditions that are common during the summer. Avoid over irrigation because water logged soils will be harmful to bene cial soil organisms as there will not be enough oxygen for them to breathe and respire.
4. Avoid unnecessary digging, as this will destroy the mycorrhizae and soil structure. With raised beds that are 4ft (1.2m) wide
I can reach the middle from either side, meaning I never have to walk on the bed meaning no compaction so no need to dig.
5. Avoid unwarranted pesticide applications, some fungicides, insecticides and
So what makes up the fertile soil that the soil association often mentions? This is what I want to cover in the remainder of this article starting
with the types of organisms that are found in a healthy fertile soil.
Types of soil organisms
Soil contains an enormous number of living organisms including bacteria, protozoa, fungi, actinomycetes, nematodes and arthropods, earthworms, and other soil fauna.
The numbers in the soil are quite mind blowing, in fact are phenomenal as set out below, this is the estimated number in one cup full of undisturbed U.K soil.
Soil contains an enormous number of living organisms
Bacteria Protozoa Fungi Nematodes Arthropods
200 Billion
20 million 100,000 meters 100,000 50,000
32 simplyvegetables
Adding garden compost to raised bed.
There are also estimated to be many different species of bacteria in the soil all of which have a purpose. Some breakdown organic matter, others convert different forms of nitrogen into a form that the plant can take up through their roots. Another form lives on the roots of legumes and helps the roots to absorb gaseous nitrogen and converts it to a form the plant can use.
Soil organisms are naturally active during certain times of the year; they are most active when the soil is warm and moist, like during late spring and early summer. If the soil dries out during the summer months, the soil organisms’ activity naturally declines. Then during the autumn and early winter, if there is rain or snow that moistens the soil while it is still warm, soil organisms may resume partial activity. As the soil cools in the winter, many soil organisms go dormant.
Soil food Web
Within the soil the organisms function as part of the soil food web which means some of the very small types are eaten by some of the larger ones. Some of the arthropods feed on