What is healthy soil biology?

Healthy soil contains a huge amount of life

Soil organisms keep soil healthy in a number of ways. Earthworms take in soil and organic matter and eject fine soil particles full of bacteria and nutrients. They also create channels in the soil that allow water infiltration and root growth. Soil fungi exude a glue-like substance which helps to clump soil and form the structure of a healthy, free draining and aerate soil. 

For soil to have a clean bill of health, we need to be mindful of its three main elements. These elements are interrelated so if one is out of balance it can adversely affect the other two. 

What do soil organisms do?

If you pull a plant out of healthy soil, on its roots will be myriad organisms living, feeding, releasing plant available nutrients, being consumed and ultimately dying in the rhizosphere (root zone). 

Alive and healthy, these organisms bring tremendous value. But like us, most of them require oxygen from the 25 per cent of soil that's air. So if soil is compacted or poorly drained, many of these micro-organisms will die, and we lose their potential to enhance productivity. 

How do worms help?

Worms take in soil and organic matter, strip out what they need and eject the rest as fine soil particles, full of bacteria and soluble nutrients. The channels they create in the soil allow water infiltration and root growth. 

How does fungus help?

Soil fungi access nutrients by using very long hyphae (filaments) to expand the range of roots. These fungal hyphae and spores exude glue-like glomalin which helps to create soil peds that form the structure of a healthy, free draining and aerated soil. 

 How does bacteria help?

Of all the organisms living in soil, bacteria are the most abundant. They are exceptionally small, single celled organisms that cannot be seen with the naked eye, however, there may be up to 10 million in a single gram of soil. Soil bacteria are extremely important for breaking down plant and animal residues as well as cycling nutrients in soil. In particular, they are involved in fixing nitrogen from the atmosphere (in partnership with clover plants) as well as converting nutrients to plant available forms.

How can we keep soil organisms healthy?

Here are three ways to support healthy, productive soil:

1. Keep it covered with vegetation. This protects the soil and live roots support soil organisms. 
2. Grow a variety of species, as different species support different organisms. 
3. Maintain good fertility to enable plants to grow more and produce more root material and to feed more exudates to soil organisms.