How to Support Soil Microbes in Your Garden

Microorganisms are key to soil and plant health in organic gardening. Microbes contribute to nutrient cycling, plant growth, and disease suppression. Without microorganisms in the soil, your plants would have a very difficult time growing. Because microorganisms support plants in numerous ways, we should support these microbial populations. Many commercial gardening methods actually cause a decline in microbial populations and force you to buy more products to support your garden. Instead, treating your garden like the ecosystem it is will give you sustainable growth and nutrient dense produce. A few ways to do this include avoiding chemicals, adding organic matter, and improving soil structure.

Avoiding pesticides and synthetic fertilizers is a great place to start when trying to support soil microbes. Pesticides are directly harmful to microorganisms in the soil, as they are designed to kill. Although you may be trying to use a pesticide to get rid of one destructive insect, those chemicals can get into the soil after being sprayed and kill microbes that are hugely supportive to plants.

Along with this, synthetic fertilizers can cause harm to soil microbes by disrupting the food chain. Many beneficial soil microbes rely on carbon as a food source, and synthetic fertilizers often just add nitrates and phosphates to the soil without any carbon material in the mix. Prolonged use of synthetic fertilizers can decrease soil microbe biodiversity and ultimately limit the amount of minerals and nutrients your plants receive. Supporting soil microbes will give your plants access to more minerals and nutrients than any synthetic fertilizer.

Instead of using synthetic fertilizers, it is better to use organic matter. Organic matter includes manure, decaying plant material, and compost. Adding organic matter to your garden feeds soil microbes and your plants. Through the process of decomposition, microbes naturally convert nitrogen and phosphorus in organic matter into bioavailable nitrates and phosphates for plants, all while feeding themselves with the carbon present.

There are various microorganisms in the soil that rely on various food sources, not only carbon. Adding organic matter also ensures that there is a wide range of nutrients to support a biodiverse population of soil microbes, whereas only adding synthetic fertilizer significantly decreases microbial biodiversity. High microbial biodiversity ensures that your plants have access to all the nutrients they need and controls the populations of pathogenic/harmful microbes in the soil.

Another way to support microbes is by having good soil structure. Good soil structure refers to good porosity and aggregation of your soil. Soil microbes use pores in the soil as habitat space, so ensuring that your soil is not compacted and is properly aggregated helps to support them. This can be done by imitating no-till practices, avoiding soil drying, and aeration. 

No-till agriculture is the process of harvesting a crop, then leaving the roots to decompose, rather than tilling the soil. This allows the soil to maintain its structure/aggregation, which maintains habitat for soil microbes. This can be mimicked in a garden bed by growing a cover crop before planting your actual crop, or you can practice this technique by simply not removing the roots of your previous crop.

To avoid excessive soil drying, which can lead to compaction, be sure to only water your garden in the morning or evening. You can also prevent this by covering your soil with mulch, straw, or rice hulls. 

Lastly, aeration is a way to increase soil porosity. Aeration can be done by physically poking holes in the top layer of soil, via organisms (like worms) moving through the soil, or by growing cover crops and leaving the roots to decompose. You can also "add aeration" to your soil by mixing lava rock or pumice into your vegging soil before planting. The porous nature of these rocks adds to the overall porosity of your soil, creating even more habitat for soil microbes.

There are many ways to support soil microbes in your garden, and your plants will certainly thank you for doing so! In organic gardening, understanding the symbiosis between plants and microbes can make growing so much easier. 

If you want to begin organic growing in your garden or flower beds, stop by our store to get all the starting materials you need!

Written by Kaitlyn Watt