Don’t Burn Your Microbial Bridges!

Don’t Burn Your Microbial Bridges!

Did you know that plants spend a good portion of their energy ‘feeding’ soil life?

The rhizosphere is an intense hub of activity in the soil. It’s in this root zone around plants that plant roots feed nearby microbes in exchange for plant nutrients. In this way, the rhizosphere is the “bridge” where unavailable minerals are turned into plant nutrients.

Here’s how it works: 

  • Roots put sugars down into the soil
  • This created an area of crowded, busy bacterial feeding in the rhizosphere
  • Roots exchange that microbial food for nutrients the plant needs

A win-win in the rhizosphere

Plant sugars from the roots feed the microbes; the bacteria and other organisms living in the rhizosphere make nutrients available to the plants AND provide a protective layer against pests and diseases. 

Why do plants need the microbial bridge?

Plants need the minerals found in the soil to grow, photosynthesise, flower, pollinate and produce fruit or seeds. Although soils are composed of around 45% minerals, most of those minerals are not in a form the plant can use. Microbes are the bridge between the soil minerals and the plant roots.

  • Nitrogen – Although plants are surrounded by nitrogen in its gaseous form in the atmosphere, only microbes are able to turn it into a usable form. Microbes also transform soil organic nitrogen into mineral nitrogen (ammonium and nitrate) that plants can take up. 
  • Sulphur – It takes microbes to change organic sulphur in the soil into plant-available sulphate.
  • Phosphorus Organic phosphorus is mineralised to plant-available forms only through microbial activity. 
  • Many other micronutrients also benefit from the microbial bridge to make them plant-available. 

With nutrient movement and nutrient-holding capacity, microbes can:

  • Change the form of a nutrient to make it plant-available 
  • Change a mineral’s acidity or alkalinity 
  • Hold nutrients in a way that makes it easier for a plant to take them up when needed

Microbes are the bridges that make the soil/plant system work. So, how do you build that bridge?

Enhancing the strength of the microbe bridge comes down to a number of different practices that involve feeding an abundance of soil biology year-round:


Diversity leads to abundant biology, which is key to building a strong microbe bridge. Having different kinds of plants means a more diverse array of soil life, since plants are specific to their microbes.


By growing mixed plant species, you are able to populate a more heterogeneous group of microbes in the soil. This means that no one population can become dominant, building a stronger microbial bridge that provides a variety of minerals essential for plant health.

Start taking care of your soil biology

By switching your focus from chemical inputs to taking care of soil biology, this allows for a stronger and more effective microbial bridge. Rather than relying on soluble fertilisers for plants, the microbes are able to effectively deliver the correct nutrients to plants in the right forms and quantities. 

Depending on manual inputs is expensive and unsustainable; by focusing on soil health and biology, building a strong microbial bridge will put you on the road to successful farming in the future. 

Get in touch with the Zylem team to find out more about how to build a better microbial bridge.

Contact us on 033 347 2893 or send your enquiry to

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