Dirt is dead, soil is Alive! A single tablespoon of soil contains billions of microorganisms including bacteria, fungi, nematodes, insects, and earthworms all working together to support plant growth and productivity. Not only do soil microorganisms nourish and protect plants, they play a crucial role in essential ecological processes such as climate regulation, mitigation of drought and floods, soil erosion prevention, and water filtration. The living soil where we grow our food is perhaps the most important resource for a sustainable and healthy future for the earth’s human population.
Types of Soil Organisms
- Decomposers such as bacteria, fungi and nematodes break down or “recycle” dead plant and animal matter, transforming it into nutrients plants can uptake. Worms and insects shred and grind organic material into smaller pieces bacteria and fungi can easily process.
- Some soil organisms directly benefit plants by forming symbiotic (mutually beneficial) relationships. Specialized mycorrhizal fungi bring hard-to-reach nutrients and water directly to plant roots while the plants provide the fungi with food in the form of carbohydrates. Similarly, Rhizobia bacteria specifically colonize the roots of legumes to form nitrogen-fixing nodules. Other beneficial fungi like Trichoderma live within the roots of plants and bacteria such as Bacillus aid with disease suppression and nutrient uptake.
Tips for Supporting Living Soil
1. Test your Soil
Whether you’re growing six plants or farming multiple acres, understanding the chemical makeup of your soil provides critical insight into how your nutrients are cycling and the health of your soil from season to season. More information on Biologic Crop Solutions soil sampling services is available here.
2. Add Organic Material
Soil organic matter is composed of living plant roots and organisms, decomposing plant and animal material in varying stages of decay and enzymes secreted by soil organisms that act like glue to bind soil particles. Humus is the most stable and fully decomposed form of organic matter with the greatest capacity to improve soil structure and fertility.
Adding a high-quality compost or other organic material such as worm castings and/or humus to existing soil can provide essential macro and micronutrients as well as increase the availability of air and water throughout the soil, allowing for healthy root growth.
3. Water Wisely
Plants and soil microbes require varying amounts of moisture and air movement to successfully survive.
Soil compaction and excess disturbance can negatively impact plant growth and soil health. Consider creating designated garden pathways to minimize tamping soil. In most instances soil micro-environments rich in fungal colonies are best left undisturbed by excess tillage.
Soil organisms require a damp but not soggy environment. Water effectively to achieve soil saturation similar to a wrung-out sponge.
4. Protect your Soil
Cover the delicate, microbe-rich top few inches of your soil with mulch or plant a cover crop to protect it. In addition to providing erosion control, cover crops supply food and extra organic matter to the soil underneath. Mulch applications help soil retain water and can prevent soil-borne pathogens from inadvertently spreading to plant leaves and stems.
5. Avoid Chemical Use
Chemical pesticides, fungicides and herbicides can kill beneficial soil microbes and insects and destroy intricate soil ecosystems. Consider plant or microbially-derived alternatives to chemical controls or source predatory insects to target pests.
6. Rotate Crops
Growing crops from different plant families each season can help minimize the impact of disease-causing pathogens and prevent nutrient depletion. Some crops, such as legumes, are capable of adding nutrients back to the soil for subsequent plant rotations.
Anne Sawyer and Julie Weisenhorn. “Living soil, healthy garden” https://extension.umn.edu/managing-soil-and-nutrients/living-soil-healthy-garden
Caitlin Hodges. “How do soil microbes influence nutrient availability?” https://soilsmatter.wordpress.com/2018/06/01/how-do-soil-microbes-influence-nutrient-availability/
Catherine Moravec, et al. “The Living Soil” https://cmg.extension.colostate.edu/Gardennotes/212.pdf
Mike Amaranthus and Bruce Allyn. “Healthy Soil Microbes, Healthy People”. https://www.theatlantic.com/health/archive/2013/06/healthy-soil-microbes-healthy-people/276710/
Natalie Hoidal. “Should you add microbial soil amendments to your garden?”. https://extension.umn.edu/yard-and-garden-news/should-you-add-microbial-soil-amendments-your-garden#sources-2851410