Soil Biology: The Key to Healthy Plants

I have an old BCS tractor with a tiller on it. It’s a beast! The strongest tiller I’ve ever owned. But I haven’t even started it in years. I stopped tilling my garden because I learned it harms the soil. It damages the soil structure and its biology.

The biology of your soil is even more important than soil chemistry. The “N-P-K” that everyone talks about is just a small piece of what makes healthy soil. Healthy and balanced biology makes those nutrients (and many others) available to plants, and plants can’t get the nutrients they need when the biology isn’t balanced. This blog post will briefly cover what makes up healthy biology, what harms it, and best practices for building healthy biology in your soil.

What Makes Up Healthy Soil Biology?

Healthy biology in your soil is full of life. There is a complex ecosystem that includes:

• Bacteria: These tiny organisms help break down organic matter. They release nutrients that plants can use.
• Fungi: Mycorrhizal fungi form a network with plant roots. They help plants absorb water and nutrients.
• Protozoa: These single-celled organisms eat bacteria. They release nutrients in a form plants can use.
• Nematodes: Some nematodes eat bacteria, fungi, or other nematodes. They help cycle nutrients in the soil.
• Earthworms: These creatures mix soil as they move through it. They break down organic matter and create tunnels for air and water.

This ecosystem works together to create a balance in your soil that supports plant growth and many other life forms. The soil ecosystem includes many other parts besides the ones listed above.

What Harms Your Soil Biology?

Several factors can harm the biology of your soil. These include:

Chemical Fertilizers

Chemical fertilizers harm the soil ecosystem. They often contain high levels of nitrogen, phosphorus, and potassium. These nutrients can build up in the soil and disrupt the balance of microorganisms. Some fertilizers also contain salts, which can harm beneficial soil organisms.

Synthetic Amendments

Synthetic amendments, like pesticides and herbicides, harm the soil. They are designed to kill something, hence the suffix “CIDE.” (Think homicide, genocide, suicide.) When you see “cide” on the end of the word, it means kill or destroy.

These chemicals kill beneficial microorganisms right along with the bad ones. They also disrupt the balance of the soil ecosystem. If your biology is out of balance, soil health (and plant health) will suffer.

Tilling Harms Soil Biology

Tilling destroys soil structure. It breaks up the soil and disrupts the network of mycorrhizal fungi, making it harder for plants to absorb water and nutrients. It kills beneficial earthworms and other creatures. Tilling also exposes soil to air, which can cause organic matter to break down more quickly.

Overwatering

Overwatering is bad for soil health and plant growth for several reasons:

• First, it creates waterlogged conditions that can suffocate plant roots. Roots need oxygen to breathe, and excess water fills the air spaces in the soil. This lack of oxygen can lead to root rot and other diseases, weakening or killing plants.
• Second, when too much water moves through the soil, it can wash away vital nutrients. This leaves the soil nutrient-deficient, and plants struggle to get the nourishment they need to grow properly.
• Third, overwatering disrupts the balance of soil microorganisms. Many beneficial soil organisms, such as bacteria and fungi, require a balanced environment with proper aeration. Waterlogged soil can create anaerobic conditions, which can harmful microbes that thrive in low-oxygen environments. These harmful microbes can produce toxins that further damage plant roots.
• Finally, overwatering can lead to soil compaction. As water saturates the soil and evaporates, it can cause the soil particles to pack more tightly together, reducing pore space. Compacted soil is harder for roots to penetrate and can further restrict water and nutrient uptake.

Avoid overwatering to maintain healthy soil biology and support plant growth.

Best Practices for Building Healthy Soil

To build healthy biology in your soil, follow these best practices:

Add Organic Matter To Improve Your Soil Biology

Adding organic matter to the soil, such as compost, manure, and plant residues, helps support healthy biology. It provides food for soil organisms and helps improve soil structure.

Chemicals Destroy The Biology Of Your Soil!

Instead of chemical fertilizers, use organic fertilizers. These include compost, manure, and other natural materials. Organic fertilizers release nutrients slowly, which supports healthy biology.

Reduce or eliminate the use of pesticides and herbicides. Instead, use integrated pest management (IPM) techniques. IPM includes using beneficial insects, crop rotation, and other methods to control pests.

Use Cover Crops

Cover crops help protect and improve soil. They add organic matter, prevent erosion, and support healthy soil. Common cover crops include clover, rye, and vetch, but there are many to choose from.

Minimize Tilling

Minimize tilling to protect the structure and biology of your soil. No-till or low-till farming methods help preserve the network of mycorrhizal fungi and maintain organic matter in the soil.

Practice Crop Rotation

Crop rotation involves planting different crops in the same area each year. This helps prevent the buildup of pests and diseases and supports diverse biology throughout your soil.

Mulch

Mulching helps protect soil and supports the biology of your soil. It keeps the soil moist, reduces erosion, and adds organic matter. Use organic mulches like straw, leaves, and wood chips.

Links for Further Reading

• The USDA’s Soil Biology Primer has a lot of good information. One of the authors is Dr. Elaine Ingram, a brilliant soil scientist!
• Dirt to Soil by Gabe Brown is excellent. Highly recommended!
• Teaming With Microbes is the first in a series of four books that explore and explain soil biology in an easy-to-understand way.

Focusing on the biology of your soil can create a healthy, productive garden or farm. Healthy, balanced biology makes nutrients available to plants, supports plant growth, and creates a balanced ecosystem. In future posts, I’ll dig deeper into these topics, so subscribe for updates! Thanks for reading

Doc Marlow