This guide will teach you the fundamentals of living soil to turn your garden into a growing machine. It is the best way to grow organic crops!
In this guide you will learn:
- Living soil terminology and components
- How the soil food web works
- What plants do to control the environment in their favor
- Why working less work will get you more out of your garden
- That organic farming can be cheap and easy
Do you know the adage of “work smarter, not harder”? That’s the underlying benefit of living soil. When you get your soil recipe right, your garden will output the healthiest harvests you have ever seen.
By mastering these strategies, you’ll be able to grow anywhere in the world with soil and a workable climate.
The key is to be lazy and let the soil microbiology do your work.
What is living organic soil?
Living soil is a productive organic system that produces healthy harvests with minimal inputs.
Sounds nice, right? It’s the counter method to modern agriculture where we toss chemical compounds in the soil to produce lackluster results.
As it turns out, living soil naturally produces better results than conventional agriculture if we just allow it to do its thing.
The term “chemical” often gets a bad rep – but chemicals aren’t the problem here. After all, plants need chemical compounds to survive. Those are the plant nutrients. The distinguishing factor between modern agriculture and living soil is how those chemicals get to the plant.
This sort of agriculture is also called true living organics, no till, ROLS, and other terms that the cannabis community uses on a regular basis to describe similar techniques. The core concept shared by all the agricultural methods is that we use organic amendments and let the soil microbiology do the work.
Now, depending on who you ask, there are between 15 and 42 essential nutrients for optimal plant growth. The organic matter in your soil is a treasure trove of these nutrients, and there is rarely need to add in supplemental nutrients.
Due to their chemical structures, natural nutrients in the soil can’t be directly used by plants. The nutrients first need to convert into their plant available forms through a decomposition process.
As a solution to this puzzle, plants have masterminded a genius strategy. The plants “farm” microbes which use enzymes to break down nutrients in the soil for the plants.
Enter the soil food web, where plants maintain beneficial relationships with bacteria and fungi for access to locked up nutrients in the soil.
The key to succeeding with organic living soil is in understanding the soil microbiology. Instead of feeding plants directly, you farm the microscopic life in the soil, which in turn provides for your plants. Though it may sound like an inefficient and round-about method, if you focus on building your soil you will truly end up with higher yielding crops, and way less legwork.
Does that sound crazy? That’s because it is.
Let’s dig in deeper.
The benefits of growing in living soil
If your soil is alive, there are so many direct and indirect benefits. If your soil is dead, well, we call that dirt. But don’t worry! Soil is a resilient system that can quickly recover.
Let’s take a quick look at a chart comparing the features of dead dirt and living soil.
Dead Dirt vs. Living Soil
| ||Dead Dirt||Living Soil|
There’s a clear winner here. Living organic soil provides the perfect environment for your plants!
The benefits of living soil explained:
- Due to a strong soil structure built by living organisms, soil is less likely to erode.
- Water slowly permeates through the structure, ending up clean and drinkable.
- Nutrients are held, retained, and given to plants in an optimized form.
- Roots extend deep into the earth, providing for drought resistant and healthy crops.
- You get increased yields since your plants work less to access more nutrients and control exactly what they get.
- Crops retain more nutritional content when we consume them because they had access to more nutrients when they grew.
- The soil that you develop continues to improve and spreads to the surrounding area.
- Input costs are kept to a minimum since the soil produces natural plant nutrients.
- You have no need for toxic chemicals.
- Plant diseases and pests are opportunistic, and your healthy plants don’t give them the opportunity to attack. (read our guide on common pests)
Living soil structure
To grasp the big picture of the organic living soil system it is important to know all of the individual components and how they work together.
Soil is a structure composed of minerals, water, air, organic matter, and microorganisms.
Natural weathering breaks larger rocks down into tiny pieces over time, and we classify the size of those small mineral particles as either sand, silt, or clay.
The famous soil texture triangle above shows how different ratios of these materials affect characteristics of your soil.
Sand particles are bigger than silt particles, which are larger than clay particles. When these components mix, they determine the key soil factors of surface area, porosity, and permeability.
A single handful of smaller particles has more available surface area and porosity than the same sized handful of large particles. Higher surface area and porosity means there is more space for microbes and nutrients to attach to the material.
Larger particles in the soil increase the permeability, allowing for air, water, roots, and organisms to move efficiently throughout the mixture.
Compaction happens when pressure pushes particles together, resulting in decreased porosity and permeability, which means air, water, and organisms have a harder time moving around.
The majority of soil life requires water to remain active. Good old H2O flows through the soil in three distinct patterns.
- Gravitational water flushes through your soil, following the path of least resistance and transporting nutrients in the process.
- Capillary water is held in the soil and acts as a hydration reserve for your plants. Particle pores store capillary water, particularly the very porous clay and humus materials.
- Hygroscopic water forms a durable thin moisture layer on the surface of soil particles and is used almost exclusively by microbes.
An ample supply of oxygen is essential to a healthy soil biome. When there is oxygen in the soil, it’s called an aerobic environment. When the environment lacks oxygen, it’s an anaerobic environment.
Different kinds of life in the soil thrive in each condition. The beneficial life tends to all be aerobic, and the harmful, problematic, life is generally anaerobic.
As water and organic life move through the soil, stale oxygen is pushed out and fresh oxygen cycles in to fill the holes. This air displacement maintains a healthy aerobic environment which aerobic microbes use for respiration, creating carbon dioxide in the process. Your plants love carbon dioxide which dramatically increases their growth.
Organics are decaying plant and animal matter and serve as the basis for the nutrients that plants need. Until microbes fully decompose the organic matter, the plant can’t access the nutrients, but microbes can.
Organic matter can be classified as either soft or hard. Soft organics have exposed edges or are the green, easy to penetrate materials. Hard organics are things like sticks, bones, and leaves. They have tough exteriors and more complex chemical compositions, which take them longer to break down.
Soil microbes devour the organic matter as food. The ratio and availability of their food determine the growth rate of microbe populations. If the organic matter is mostly soft materials, bacteria populations boom. If the organic matter is mainly fungi-friendly hard materials, those populations will get a boost.
When the decomposition process reaches its end, organic matter is considered humus. Humus is essentially a beneficial long term food source in the soil which increases porosity.
The main microbe considerations are bacteria, fungi, protozoa, and nematodes.
Microbes are a plant’s best friend. Well, that’s true as long as they are the aerobic variety. Aerobic microbes are beneficial to your plant while the anaerobic ones will quickly abuse and damage your plant.
Bacteria capture passing nutrients and form soil aggregates which increase porosity and help store nutrients as reserves. They break down massive amounts of soft organic matter and convert nutrients into their plant available forms.
Fungi aggregate soil and create fungal pathways throughout the area, increasing porosity, retaining massive amounts of water, and allowing nutrients to be stored and transported vast distances. As if that wasn’t enough, they also break down soft and hard organic matter, converting nutrients into plant available forms.
Both bacteria and fungi store their plant available nutrients inside of their biomass, called immobilization. When the predatory protozoa, nematodes, and microarthropods consume bacteria and fungi, the immobilized nutrients release into the soil. This spreading of plant available nutrients is called mineralization.
Plants, the soil controllers
Most plants have just one thing on their mind – survive so that they can reproduce. For that, they (to put it simply) need safety and nutrients, which comes from a healthy organic soil structure.
Plants have evolved complex chemical handshakes with beneficial microbes so that the soil is under their control, manipulating the environment to ensure that the soil provides everything they need to flourish. By managing bacterial and fungal cultures, plants rule the soil.
Plants need help accessing soil nutrients
In the soil, everything is a competition for survival. There are limited life-sustaining nutrients available in a given location, so plant life has developed several smart ways to win the battle. It’s not only plants that fight for nutrients – all other soil life tied in a similar competition, which you as a farmer can use to your advantage.
The area around roots where plants and microbes exchange nutrients is called the rhizosphere. Roots have a limited physical reach, and so they are only able to uptake nutrients deposited in their rhizosphere.
The plant has a vested interest in making sure that nutrients end up in their rhizosphere, and so they trade nutrients produced through photosynthesis with microbes. These microbe foods are called exudates, a mixture of sugars, proteins, and carbs that plants pump into the soil through their roots.
The exudates attract microbes to the rhizosphere by feeding them, and the microbes feed the plant by converting locked up nutrients in the soil into their plant available forms. These microbes also help protect the roots against pests and disease by outcompeting the dangerous microbial life in the area.
It is important to see this nutrient transaction between plants and microbes as an exchange. Plants get their nutrients, and the microbes get theirs. Everyone is happy and benefiting from the relationship.
How the nutrients change hands
Soil is made up of many small particles that have negative or positive charges called ions. Negatively charged ions are anions, and positively charged ions are called cations. Nutrients can be either cations or anions, depending on their chemical structure.
CEC is a measurement of the soil’s ability to hold positively charged ions, and therefore retain nutrients.
Opposite charges attract, so a soil with a high CEC that can hold many cations means there is a large amount of negatively charged sites available where they can attach. Organic materials, humus, and clay have huge negative charges, which significantly increases CEC.
These materials hold on to nutrients through chemical bonds that are dissolved by bacteria and fungi, and then those microbes immobilize the nutrients in their biomass.
Nematodes, protozoa, and microarthropods feed on the bacteria and fungi, absorbing what nutrients they need, and mineralizing the remainder. The nutrients are now available to the plant, and since the bacteria and fungi are often located in the rhizosphere, the plant has immediate access to those nutrients. Feeding the microbes their exudate was all worth it.
How your plant ingests the nutrients
Plant roots have exchange sites where they give off either positively charged hydrogen for cations or negatively charged hydroxy for anions. By doing this chemical dance, the plant can finally absorb the available nutrients in the soil.
The pH measurement of soil changes when the concentration of hydrogen changes. As plants hold and release hydrogen, the pH moves either more acidic or alkaline. The microbes have an effect as well – bacteria produce bioslime that keeps the soil alkaline and fungi provides more acidic soil.
Plants can grow in a wide variety of pH values, though they often perform best in individually optimized pH ranges. There are tons of micro-sites throughout the soil where the pH values differ based on that particular location, which more-so affects the microbes than the plant. The microbes need certain pH ranges to perform their biological activities, and since plants need microbes, the plant helps to maintain the proper pH by feeding and growing the correct bacteria or fungi for the situation.
Putting it all together
Plants farm microbes. Microbes eat organics. Microbes get eaten. Nutrients are mineralized. Happy plants.
Now that you have an understanding of soil science, try making a soil mixture for yourself! Check out our guide on how to create your own super soil
That covers the fundamental basics of soil science. Don’t work hard, don’t spend fortunes on chemical fertilizer, just let your soil do the job. That’s the magic of soil biology!
There’s more to learn and detail to discover, like the many different types of bacteria and fungi, the higher level predators in the soil food web, the specific nutrients and fixation pathways, how moisture affects microbes, etc. You should now have a solid foundation to help learn those specifics, and be sure to stay tuned for my future posts diving into further detail.
What do you think I should cover next? Let me know in the comments!