How to Improve Soil Biology

White mycorrhizal fungal threads around plant roots

Introduction

What is meant by soil biology? Isn’t soil just a bunch of minerals? The answer is no and your soil contains so many living organisms, most of which are not visible with the naked eye, but all are important for the soil’s ecosystem. The visible organisms are earthworms and small mammals like gophers, moles or voles. However, the vast number of organisms are only visible with a microscope such as bacteria, fungi, nematodes, protozoa and more.

What does all of this biology have to do with the health of my garden? Well the answer is without soil biology, your plants will have problems accessing nutrients like nitrogen and phosphorus, both essential for growth. What can be done to improve and increase your soil’s biological makeup? They need adequate organic matter, good aeration, proper moisture, and a fairly neutral pH. One of the easiest things to do to improve your soil biology is to work in some good quality compost. The compost will help hold onto moisture, help aerate the soil by maintaining soil porosity and supply nutrients to the microbes already living in your soil.

Another important practice that will help improve soil biology is to plant a cover crop in areas that you are not actively growing in. Cover crops can be planted in the fall and cut down in the spring, or grown in the summer and finishes in the summer. Don’t forget to inoculate your cover crops if they contain legumes and inoculate legumes you are growing for food, like bush beans or pole beans. The Rhizobium bacteria in the inoculant forms a symbiotic relationship with the plants’ roots and converts atmospheric nitrogen into a plant usable form, in turn the plant supplies the bacteria with carbohydrates needed to live. Any extra nitrogen the plant does not need is stored on the roots and can be used by the following crop.

If you are interested in reading more about soil biology, you can read our articles Weaving the Soil Food Web or The Dirt on Mycorrhizae.

Choose a Root-Zone Product by Formulation

Compare mycorrhizal inoculants by fungal type, carrier, application method, and package directions. For phosphorus or soil concerns, use a soil test and review the complete fertility program before adding an input.

When soil-building plans include raw peas, beans, clovers, vetches, or other legumes, use the Legume Inoculant Compatibility Chart to identify the compatible rhizobia group before planting.

FAQs About Improving Soil Biology

What is soil biology, and why is it important?
Soil biology refers to the community of living organisms found in soil, including bacteria, fungi, protozoa, nematodes, arthropods, and earthworms. These organisms contribute to decomposition, nutrient cycling, soil structure, and other processes that support healthy plant growth. Soil is therefore much more than minerals; it is a living ecosystem containing organisms of many sizes.
How does organic matter support soil biology?
Organic matter provides food and habitat for many soil organisms. As microbes and other organisms decompose plant residues and other organic materials, nutrients are transformed and cycled through the soil. Adding organic matter and maintaining plant residues can therefore support biological activity while also contributing to soil structure and nutrient cycling.
Do cover crops improve soil biological activity?
Cover crops can support soil biology by keeping living roots in the soil and supplying organic material both above and below ground. Living roots release compounds that feed microorganisms in the rhizosphere, while cover-crop residues provide additional food for the soil food web. Diverse cover crops and rotations can also contribute to broader improvements in soil health.
What do Rhizobium bacteria do for legume plants?
Certain bacteria commonly referred to as rhizobia form symbiotic relationships with legumes by colonizing their roots and forming nodules. The bacteria fix atmospheric nitrogen into forms the plant can use, while the plant supplies the bacteria with energy derived from photosynthesis. Different legumes have different rhizobia requirements, so an appropriate inoculant should be selected for the specific legume.
What conditions are important for healthy soil biology?
Soil organisms are affected by factors including organic matter and food sources, moisture, temperature, aeration, pH, soil structure, and physical disturbance. Maintaining living roots, minimizing unnecessary disturbance, keeping soil covered, and encouraging plant diversity are among the USDA NRCS principles for supporting soil health. Because different organisms have different environmental requirements, there is no single ideal condition for every soil organism.
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