Tony O’Neill, gardener and author of the popular “Composting Masterclass” and “Your First Vegetable Garden,” combines lifelong passion and expert knowledge to simplify the art of gardening. His mission? Helping you cultivate a thriving garden.
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Soil Mites are ubiquitous in almost every landscape globally, from deserts to swamps across the poles and the equator.
It takes remarkable evolutionary adaptability for a species to survive 410 million years, the oldest mite fossils found. Soil mites thrive wherever organic materials, fungi, and bacteria are essential for soil health.
Table of Contents
How Overwatering Affects Beneficial Soil Mites
Your soil biota is adaptable to excessive watering, but your plants aren’t. Because water is heavier than air, protracted overwatering expels all the air trapped in healthy soil and causes plants to drown.
What happens is that latent soil fungi (Rhizoctonia, Phytophthora, Pythium, and Thielaviopsis) flourish in anaerobic environments, causing root and basal stem rots.
Your greatest allies in preserving soil saturation porosity, a soil’s ability to trap air even when saturated, are soil mites. In their soil activities, which we’ll review later, they create microscopic tunnels, binding soil particles together to form aggregates. These tunnels trap air, allowing plants to breathe even when the soil is saturated.
Extended wet conditions compromise these tunnels and may even cause them to collapse and aggregates to disintegrate. This bodes poorly for plants growing in that environment, as only select plants are adapted to thriving in anaerobic environments.
More About the Tiny Mites In Plant Soil
Soil Mite History
I often wonder how freaked out most people would be if they knew the abundance and diversity of organisms below their feet. In any given shoe-size spot on earth, there are billions of micro- and mesobiota from tens of thousands of species.
We should be hugely grateful that this is true because without these rarely acknowledged organisms, life as we know it would not have evolved on this beautiful planet, Zip, nothing, nada.
So where does the soil mite fit in? Fossils show that they’re approximately 100 million years older than the homo sapiens but came about 35 billion years after bacteria and fungi. So, soil mites have been around for about 410 million years, juveniles compared to their meals, fungi and bacteria.
Soil Mites Identification
Soil mites are tiny relatives of the tick, spider, and scorpion (arachnids), an arthropod in the mesofauna group of soil organisms. A cupful of healthy soil can have a thousand mites from different soil mite species.
While bacteria are the most abundant microbiota, mites are the leading group of mesobiota, followed by the macrobiota groups of larvae, pot worms, beetles, centipedes, millipedes, ants and spiders.
These form a critical, generally balanced soil food web with varying predator/prey relationships. Diversity is essential to keep all the cogs connecting and moving. Remove one cog, and the dependent elements of the system collapse. Diversity contributes to maintaining a system’s balance.
What Are These Small Moving White Dots in my Garden Soil?
Micro, meso, macro; small, medium, large. Meso biota and bigger than microorganisms but smaller than ants (macrobiota). Soil mites are tiny organisms with diameters ranging from four-hundredth to an eightieth of an inch (0.1mm to 2mm).
| Classification | Size | Class |
|---|---|---|
| Microflora | Microscopic | Bacteria, fungi, actinomycetes |
| Microfauna | Microscopic | Protozoa & nematodes |
| Mesofauna | 0.1 – 2mm | Soil mites, springtails, and predatory nematodes |
| Macrofauna | 2 – 20 mm | Predatory soil mites, sowbugs, ants, spiders, pot worms and earthworms |
The soil mite life cycle is divided into four stages: egg, larva, nymph, and adult. The larval stage molts into the nymphal stage when the egg hatches and the nymph grows into an adult in two or more iterations. Soil mites have three pairs of legs as larvae and four pairs of legs as nymphs and adults.
Typically, it would help if you had a microscope to see mesobiota species, though some can be observed with the naked eye (or magnifying glass). You may spot them if they move over a clean tiled surface like a patio in spring.
The Role of Soil Mites and other Soil Creatures
The soil ecosystem is an interdependent life-support system composed of the pedosphere, air, water, minerals, organic matter, and macro-, meso- and microorganisms.
These organisms, called the soil food web, improve soil ecosystem functionality. Soils without any living organisms are dirt. The difference between dirt and soil is that the latter teems with life and can better support plant growth. The soil food web contributes to soil health.
- Decompose organic matter to make hummus.
- Glue soil particles together for improved soil structure.
- Retain nitrogen and other nutrients.
- Make soil nutrients available to the plant.
- Protect roots from diseases and parasites.
- Produce hormones that help plants grow.
- Help the soil better manage water and air availability.
Naturally grown plants depend on the nutrients and water made possible by soil life. All living organisms, in this case, plants and soil biota, form relationships that allow them to grow and reproduce.
Another way of looking at this is that life is made possible when there are resources to exchange between a life form, its environment, and the other occupants in that environment.
In soil, soil organisms benefit from plants. In turn, soil organisms support plant health by breaking down organic matter, cycling nutrients, improving soil structure, and managing populations of soil creatures that can be harmful. If the plant thrives, the organisms thrive, and vice versa.
Soil Mites and The Soil Food Web
Healthy soil teems with life, including bacteria, fungi, actinomycetes, protozoa, and algae. It consists of about 5% organic matter, the critical food source for biodiversity. By consuming organic materials and blending them with the minerals in the soil, the soil biota recycles nutrients and compounds for plant availability.
Sticky compounds, such as those found on the skin of earthworms and others created by mites, fungi, and bacteria, hold soil particles together. A mixture of organic materials, soil minerals, soil mite excrement, and earthworm casts creates an aggregated soil.
And thus, the soil mites and the whole soil food web work together to create an environment where plants can thrive. Soil mites and their friends help develop a soil that preserves the availability of air, water, and nutrients for plants, removes contaminants, and performs soil structure maintenance.
What do Soil Mites Eat?
The soil food sources affect the soil biota population diversity. Soil mites, the generalist soil scavengers, are more abundant in soil rich in available crop or garden debris and great bacteria and fungi.
“Well, if she’s going to the party, I’m going too.” The abundance of microorganisms determines the mesofauna populations (medium-sized soil animals), triggering the numbers and diversity of macrofauna (the bigger soil inhabiters).
Every species and group, including soil mites, can be found where there is enough food, space, and moisture.
Leaf Litter and Soil Mites
Wherever there’s organic matter, there are soil mites and billions of other soil organisms. In soil, these creatures are concentrated around roots, in plant debris, in humus, and in and on soil aggregates. Soil mites love clays or soils rich in plant residue (biomass).
Your soil, even a teaspoon, is a living, breathing ecosystem with seasonal and daily rhythms. Soil mites are generally sedentary, seldom traveling more than a few yards in their three to seven-year lives.
It becomes clear why no till or low till is so passionate for those aware of these ecosystems. Every cultivation activity disturbs the ecosystem’s habitat. Deep plowing and using herbicides and pesticides destroy nature’s way of ensuring your plants get the best it has to offer.
In the absence of these ecosystems, we need artificial fertilizer to try and get some nutrients plant-available, but, as we’re finding, it’s unsustainable because the soil organisms do more than make plants nutrients bioavailable.
Soil Mites and Soil Functions
| Functions | Organisms involved |
|---|---|
| Maintenance of soil structure | The combined efforts of invertebrates, arthropods, and other soil organisms |
| Decomposition of organic matter | Various saprophytic and litter-feeding invertebrates (detritivores), fungi, bacteria, actinomycetes and other micro-organisms |
| Water (and air) regulation | Most invertebrates, some mesofauna, and the soil engineers, macrofauna. |
| Carbon sequestration | Mostly micro- and mesofauna and plant roots |
| Soil detoxification | Mostly microorganisms made possible by soil mites that break them down |
| Nutrient cycling | Mostly mimicroorganismsbut access to these nutrients is enabled by soil mites. |
| Suppression of pests, parasites and diseases | The chief nematode and fungi predator is the Mesostigmatid soil mite. Some bacteria and fungi are also involved in suppressing pathogens. An increased soil biota diversity improves soil health and plant resilience. |
| Symbiotic and asymbiotic relationships with plants and their roots | Rhizobia, mycorrhizae, actinomycetes, diazotrophic bacteria and various other rhizosphere microorganisms soil mires and ants |
| Plant growth control | Most soil biota |
FAQs on What You Need to Know About Soil Mites and Overwatering
Soil Mites and Overwatered Soil
Soil mites are comfortable in high humidity, and some predatory soil mites need high humidity levels for their eggs to hatch. Predaceous mites are responsible for managing nematode populations and those of organisms that may be harmful to your plants.
What soil mites don’t like is soil that is low in carbon content and dry, but neither do your plants.
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