According to agricultural professor Dr. Teruo Higa, there are only four types of soils: Disease Inducing, Disease-Resistant, Zymogenic or Nutrient-sharing soils , and Nutrient - Synthesizing soil.

In this article we discuss the connections between microbes and soil structure, nutrient availability, and plant disease.

DR. HIGA'S SOIL CLASSIFICATIONS

In Dr. Teruo Higa book Agricultural Utilization of Microorganisms For Environmental Conservation (only available in Japanese), he identifies four types of soils: Disease Inducing soil, Disease-Suppressive soil, Zymogenic soil, and Synthetic soil.

1. DISEASE-INDUCING SOILS

These soils tend to have a high percentage of fusarium. These soils have been poorly managed, tend to be compacted, drain poorly and support the growth of putrefactive microbes. Due to the high populations of putrefactive bacteria, they tend to put off foul odors such as ammonia from manures or high nitrogen fertilizers. These soils are conducive to pests, disease, and root rot and erode easily as there are little to no beneficial soil microbial communities to improve the soil structure. This is a very common classification for poorly managed agricultural soils that use high amounts of chemical fertilizers.

2. DISEASE-RESISTANT SOILS

These soils contain lots of soil microbial communities. Most of these microorganisms will be beneficial microorganisms including penicillium, Trichoderma, and Streptomyces genus. The texture is crumbly, where water can penetrate the soil easily. There is a low incidence of soil borne diseases in this soil, and plant yields are high. Due to high populations of beneficial microorganisms, the soil does not have any foul odors.

3. ZYMOGENIC or NUTRIENT-SHARING SOILS

The use of EM in various ways and forms introduces the fermentation pathway of organic-matter recycling. These soils tend to be dominated with fermentative microorganisms such as lactic acid bacteria and yeasts. Fermentation creates zymogens or enzymes, and a host of other beneficial substances which serve as food and substrates for other beneficial microorganisms. Populations of plant pathogens are low and disease suppression is high. Both population density and species diversity of beneficial microorganisms increase, including both aerobic types and beneficial anaerobic types (facultative anaerobic or fermentation types).

Earthworms and other soil micro-fauna increase even further in numbers, species diversity and activity. The soil starts to become a living soil. The soil structure is significantly improved and water penetration is even. Unavailable nutrients become available to plants for increased plant health. Microbial metabolites such as amino acids, polysaccharides, vitamins, bacteriocins, plant hormones, etc. are present. The soil is becoming more aerobic, teaming with life and bio-available nutrients for plants. Crop yields will be higher on these fields than on disease-suppressive soils.

4. NUTRIENT - SYNTHESIZING SOILS

"Nutrient Synthetic" microbes begin to dominate this soil. Unlike the meaning of "synthetic" when used for fertilizer or chemicals. This does not mean a "fake" or "manufactured" soil. It means a soil where things are synthesized or made. The soil naturally provides its own fertility from residues and natural processes, such as nitrogen-fixation by free-living and legume-symbiotic microorganisms. These microbes include algae, photosynthetic bacteria, and nitrogen-fixing bacteria. These are fusarium wilt suppressive soils as fusarium has a difficult time producing a strong population. Microbial metabolites are very high and Dr. Higa refers to this soil as being a "bacteria-cleansing type soil" and a natural biological control for soil borne pathogens such as blight.

HOW TO CHANGE YOUR SOILS HEALTH

This classification makes it fairly easy to identify soil microbe makeup by odors and incidence of pests and disease without going through the expense of taking soil samples and sending them to a lab.

To transition from disease-inducing soils to synthetic soils, populations of beneficial microbes need to be encouraged through proper management techniques and repeated microbial inoculation. The goal is to make soils teaming with beneficial microbial life. This will result in less disease, healthier plants, better drainage, and less pest damage.

Increasing beneficial microbial populations for increased plant health and increase disease suppression can be easy to do with a few basics.

• Maintain regular applications of EM-1® Microbial Inoculant. Dilute 6 oz of EM-1 to 1 gallon of water and water weekly.

• ​​Add high-quality organic matter such as homemade compost or your food waste pre-compost.

• ​​Foliar feed with EM-1® Microbial Inoculant. (6 oz to 1 gallon dilution)

• ​​Use all natural, low-impact fertilizers only when needed.

• ​​Use cover crops to add nutrients, even in your home garden.

• ​​Practice crop rotation, even in your home garden. Some plants such as tomato and peppers are more susceptible to fungal pathogens and switching where things are planted can help.

• ​​Be patient! Soil in poor condition can take time to transition to healthy, fertile soil.