Soil Microbes Are Just as Selfish as the Rest of Us
When scientists devised an experiment involving multiple generations of plants in drought conditions, they expected soil microbes to respond in a particular way. Here’s what happened instead...
Every year we learn more and more about the complex life that teams, deep in the soil under our feet. So far, we understand that plant roots tap into a whole network of mycelia and micro-organisms. Where, in the simplest terms, they trade sugars for nutrients and send out signals to communicate dangers across great distances. It’s a symbiotic scenario where plants and soil organisms have presumably co-evolved for millennia… or did they?
Assuming that microbes and plants worked as a team, researchers pondered, if a plant is in distress, will soil microbes adapt to answer their signals?
So, the University of Illinois Urbana-Champaign, devised a scenario in two phases. First, live soil was established in pots, both with, and here’s the new bit, without plants. Only half of the pots were watered regularly, over three generations of plant life. Giving the soil microbes time to hear and possibly answer the stressed plants calls.
In the second phase, things were shifted. Some soil was kept as is, from the first phase, and some was sterilized. While pots that had only soil initially, had plants added, and the watering routine was switched. So, some that had been regularly watered now experienced drought and vice versa.
Excitingly, the plants grown in the soils that had experienced drought in phase one (and weren’t sterilized), grew bigger and stronger than the others. But what was most remarkable; the soils that had experienced drought with no plant interaction, were the same. In other words, the microbes hadn’t shown up to help the plants. They had simply adapted to meet their own needs, without the encouragement of plant chemical signals or plant selection.
Because previous studies hadn’t contained controls without plants, researchers had always assumed that plants and microbes were involved in a dialog of co-evolution.
It’s this ‘black swan’ moment that will open a whole new area of study.
So, perhaps the next step is to re-examine our accepted theories on plant/ insect interactions and plant adaption to climate change. Many horticulturalists have assumed that planting ‘natives’ will allow for better long-term resilience. Now I’m left wondering, will they? or should we be just as concerned with what life soils contain? and what their microbes are best adapted too?
-Sara-Jane at Virens Studio
Virens is studio specializing in ecological landscape & planting design, urban greening consultation and garden writing. Get in touch today, and don’t forget to follow us on social media.
