As we learned in one of our previous posts, Microbial Growers, the soil we use as our growing medium is full of beneficial microorganisms that are essential to the health and productivity of our plants.

This time, we’re going to go into detail about the products these microbes actually produce, and how they affect the life of a plant.

First, we’ll have a quick recap of soil microbes and how they interact with plants generally. Then, we’ll get into the nitty-gritty about microbial products. To cap things off, we’ll explore how microbes can affect your soil’s longevity and the best practices for preserving and supporting these essential microorganisms.


The Invisible Life in Your Soil

In your soil are billions of microbes—organisms so small you can only see them with the help of a microscope. They’re microbes like bacteria, fungi, algae, actinomycetes, protozoa, and even minuscule worms called nematodes. The composition of soil can differ from place to place (the soil in Naples is going to be a little different from the soil in Vancouver!), but all soil contains the essential microbes needed to sustain the life of a plant.

Soil microbes are constantly at work. And if you’re looking for the biggest workhorses, look to bacteria.

Bacteria are the most abundant of all microbes. One teaspoon of soil usually has anywhere between 100 million and 1 billion beneficial bacteria, all of which help with water dynamics, nutrient cycling, and disease suppression in plants.

Bacteria also work closely with fungi. In fact, it’s likely that the colonization of Earth by plants was due in part by beneficial fungi working with bacteria. They both help with the decomposition of organic matter, turning the matter into nutrients in the soil, which then can continue to feed plant growth. Even when they microbes themselves die, they release beneficial nutrients that improve soil quality.


What Are Microbial Products, and What Do They Do?

Microbial products are exactly what they sound like: they’re things that microbes produce during the course of their lives. Microbial products often consist of metabolites, which are substances that form during metabolism. All soil microbes produce primary metabolites, but certain classifications of microbes produce both primary and secondary metabolites. Primary metabolites are essential to a microbe’s own life (like all living things, microbes have metabolisms), whereas secondary metabolites are chemical signals secreted by the microbe as a means of communication. By producing these secondary metabolites, it can effectively communicate with and influence other microbes in its environment.

Microbial products created in the rhizosphere—the zone of influence around a plant’s roots—can facilitate important aspects of a plant’s health and growth. Let’s take a look at a few bacterial products that do important work.



One of the products bacteria create are called phytohormones, hormones that help regulate plant growth. One such hormone class are called auxins, which are essential for root formation and shoot development. They also help plants with everything from stem elongation to pore closure during drought.

Other bacterial hormones help with disease resistance, by initiating chemicals that inhibit parasite growth and proteins that fight pathogens.


Nutrient Cycling

Bacteria can also make nutrients available for uptake through a number of processes. For example, bacteria help cycle important macronutrients like nitrogen and phosphorus by producing specialized proteins called extracellular enzymes. These enzymes help break down nutrient-rich molecules into bioavailable forms for plant nutrient uptake.

Bacteria also help cycle the macronutrient iron, which they do by producing iron-chelating compounds called siderophores. When plants have more iron, they can perform essential processes like photosynthesis and respiration. But the ferric iron found in soil has very low solubility, which means it won’t easily dissolve for plant nutrient uptake. Siderophores are responsible for interacting with the ferric iron and making it accessible to plants.

All of these microbial products are clearly important for helping plants thrive. But these products also tell us a lot about how microbes are the drivers of natural, sustainable agriculture. Theoretically, by keeping soil microbiomes healthy, we can improve the hardiness, health, and yield of our plants in a way that also supports the longevity of our soil.


Keep Your Microbes Safe and Healthy: Organic Growing

It’s no secret that modern farming is destroying soil across the globe; it’s estimated that over a third of the Earth’s soil will be gone by 2020 because of it. Hopefully, this alarms you as much as it does us. You can read more about the impact of modern farming practices on the soil in one of our previous articles, The Significance of Soil: Part I.

There’s good news, though. Scientists believe that microbes can be used to reinstate the fertility of degraded soils. It might take some time, but there’s hope.

So, what about us? How can we practice sustainable agriculture and take care of our soil?

Well, there are a few things we can do.

The biggest thing is that we can grow organically.

Organic growing reduces the negative environmental impact we have on our soil—we avoid using harsh chemicals that can damage the microbial life that allows our plants to thrive.

We can also avoid tilling soil, a practice which been linked to loss of microbial life, and we can feed our microbes to keep them happy, healthy, and doing their jobs. Check out our post on Microbial Growers to learn more about what you can do for the microbes in your soil.

In the end, when your microbes live their best life, your plants do too. And when the relationship between microbial life in the soil works in harmony with your plants, you can keep growing high quality, holistic, and healthful produce sustainably.