SOIL BUGS – THE FOUNDATION OF LIFE ON EARTH

In a teaspoon of healthy, living soil there should several million microscopic organisms – bacteria, algae, fungi and protozoa. There should also be some hundreds of nematodes, an earthworm or two and perhaps an inverterbrate.

Multiply this up to a hectare and you should find 1000 kg of earthworms, 1000 kg of inverterbrates, 150 kg of protozoa, 150 kg of algae, 1700 kg of bacteria and 2700 kg of fungi.

All these little bugs interact, some eating others, most consuming and converting plant sugars and soil minerals. Although they are mostly too small to be seen without a microscope and also out of sight under our feet, soil bugs are vital to the fruitful world above ground. In spite of their tremendous importance to our daily well-being and survival, soil bugs are some of the least-studied beings on our planet. Scientists estimate that so far, we have identified less than 5% of species in most groups of these bugs.

Like us, soil bugs need air to ‘breathe’, water, and the right kinds of foods. And of course, they don’t do well when being sprayed with poisons or having poor living conditions. If we can provide the right living conditions for these little workers, their productivity can be astonishing.

Carbon is one of the elements most needed by both plants and soil bugs. So it makes sense to encourage the uptake of carbon from the atmosphere and the storage of it in the soil. Carbon in soil is stored in a variety of ways, but raw and decomposed organic matter are the most relevant to everyday farming. How do we build up useable amounts of organic matter?

We can always add stuff from off the farm, like feedlot manure or spoiled hay. If we have the means to compost this material, it will be even better. Properly made compost breeds up large numbers of soil bugs and the process of breaking down the material means that some of it will be converted into stable organic matter. When the compost is incorporated into the top 10cm of the paddock, you will have bugs, decomposed organic matter and some stable organic matter. This will improve water & nutrient holding capacity and provide easily available minerals for crops or pasture.

That’s not too bad for small areas or an intensive system, but what about large pasture paddocks or broadacre crops? Well by taking a bit of a good compost, putting it into water, aerating the water and adding the type of ‘foods’ that bugs prefer, you can breed up very large numbers of bugs and then spray them out. You need to spray out some ‘food’ with them, so they don’t starve to death while adjusting to their new home.

But it’s also possible to encourage the naturally occurring bugs that you have at home all the time.

For graziers, divide up paddocks into smaller areas and run as large a herd as possible. Putting a large number of animals in a small space means they will trample a certain amount of pasture as well as leaving fair amounts of dung. This will provide organic matter for your soil bugs. Graze off the pasture, then move the animals on. Don’t graze the pasture too low, so the plants have enough leaf left to take in sunlight to recover quickly and also to produce glucose to feed the bugs around their roots.

For orchardists & vintners, grow a cover crop between rows, something low-growing and preferably a legume that will fix nitrogen in the soil. This will cover the soil surface and help to stop evaporation and will also feed a soil bug population. They in turn will make soil minerals more readily available to orchard plants. A cover crop can also be cut down to provide raw organic matter. You may have to spray it with molasses or some other favourite bug ‘food’, so the energy is available for them to break it down.

For broadacre crop growers, use the absolute minimum of tillage as this literally turns the soil bugs’ world upside down and it can take a long time for them to recover. Leave crop residues on the soil surface and direct drill the next crop in. Avoid fallows altogether if possible, try to keep a crop in the ground at all times so the bugs have a supply of glucose. You may find it is possible to use one crop as a cover crop for the next. Try rotating a variety of crops, including legumes to supply the bugs with nitrogen. This will then be released back to the next crop. Try spraying out a compost ‘tea’ of bugs to increase their numbers in the field.

For small crops growers, use the minimum of chemical sprays, instead use compost on the soil surface and try making compost tea to use as a foliar spray. Many bacteria & fungi are ‘good guys’ that will fight off bad bugs on your behalf and improve the chances of having healthy plants above ground as well as below.

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