Soil microbes are tightly bound to and often covered in soil making them very hard to evaluate by microscopy. The special magic of microBIOMETER® is the extraction powder and whisking process that separates most of the microbes from the soil. And during the 20 minute settling time allows the soil particles to precipitate leaving the extraction fluid >95% microbial.
This allows microBIOMETER® to examine 100 – 1000 times more microbes than any other method. When you apply extraction fluid to the membrane in the test card the colored microbes are captured on the surface of the membrane. A cell phone picture of the card is analyzed by the app and the intensity of the color of the microbes indicates their quantity – this is the basis for all laboratory colorimetric tests. We discovered that the fungi in soils are a slightly different color than bacteria, and so the app is able to distinguish between bacteria and fungi.
Click here to see a full video tutorial of microBIOMETER® soil testing.
Arbuscular mycorrhizal fungi (AMF) penetrate the root and establish little areas in plant root cells where they can exchange nutrients with the plant. AMF improves the nutrients available to the plant by collecting soil minerals such as phosphorous, nitrogen, magnesium and manganese through an extensive network of fine fibers (hyphae) that increase the absorptive area of the root up to a hundred-fold. In return the plant feeds the fungi carbohydrates and lipids. AMF secrete hormone like substances that stimulate plant growth and AMF encourages the establishment of nitrogen fixing bacteria. The AMF boost to plant growth comes not only from the nutrients it supplies. AMF also improves the immune response of plants making them resistant to harmful nematodes and insects as well as fungal and bacterial pathogens.
AMF shows great promise in compensating for yield losses when chemical fertilizers are eliminated or greatly reduced. AMF can reduce the need for pesticides and phosphate and nitrogen fertilizers cutting back on input costs all while building healthier soil.
In light of the known importance AMF plays in your plant’s health, microBIOMETER® now provides the fungal to bacterial ratio of your soil. This information will further assist you on your road to healthy soil while helping you lower your costs.
Leifheit, E. F., Veresoglou, S. D., Lehmann, A., Morris, E. K., & Rillig, M. C. (2014). Multiple factors influence the role of arbuscular mycorrhizal fungi in soil aggregation—a meta-analysis. Plant and Soil, 374(1-2), 523-537.
Understanding Soil Organic Matter and its impact on soil health and microbial biomass.
We are often asked what is a good level of microbial biomass (MB). There is no one answer. The level of MB you can reach is dependent on soil organic matter (SOM.) Soil organic carbon (SOC) is a large part of soil organic matter but SOM is a mixture of Carbon (C), Nitrogen (N), Phosphorus (P), Sulfur (S) and all the other minerals that microbes and plants need.
There are 2 types of SOM: Stable SOM, often referred to as humic matter; and Fresh SOM. Fresh SOM is composed of SOM material recently released from Stable SOM and any fertilizers, amendments or litter. You can compensate for low stable SOM by providing lots of fresh SOM. The key to the efficacy of fresh SOM is that it needs to be nutrient balanced*, i.e. it needs the correct balance of C,N,P, and S. That is where understanding soil chemistry and using the right additives comes in.
Think of SOM as your credit reserve. In spring, the plant starts to grow and puts out exudates that stimulate the microbes to multiply. But these multiplying microbes need more than the sugars that the plant supplies, they need the N, P, S and micro nutrients that are in SOM.
Agronomists often cultivate soil for intensive organic agriculture and those soils contain lots of fresh organic matter. The microbial biomass of these mixtures can read as high as 2000 ug MBC/gram of dry soil. As the microbes and plants in this rich soil die, they become fresh SOM. The amount of stable SOM that soil can store depends to a large degree on the type of soil because storage requires mineral surfaces for attachment and aggregates for protection. If your soil is inherently poor at storing SOM, you will need to rely on fresh SOM to feed your microbes and plants.
We highly recommend that you read the review referenced below to better understand SOM.
Coonan, E.C., Kirkby, C.A., Kirkegaard, J.A. et al. Microorganisms and nutrient stoichiometry as mediators of soil organic matter dynamics. Nutr Cycl Agroecosyst 117, 273–298 (2020). https://doi.org/10.1007/s10705-020-10076-8
Green Country Worms is a small worm farm located in Broken Arrow, Oklahoma. Their main focus is producing high quality worm castings. They started vermicomposting in 2008 when they received their first pound of compost worms. 12 years later they still love composting with worms and are fascinated with the worm castings they produce.
About a year ago they discovered their customers wanted proof of the quality of their product. While they could make claims about their worm castings, their customers wanted to see actual data. They periodically sent their castings to a certified lab to be tested, however, this is costly to do on a regular basis.
They love the microBIOMETER® soil test because it is affordable and it gives them a quick census of the microorganisms in their castings. They learned early on that a simple NPK soil test did not give them the data they were looking for. Being research minded they were also happy to find out that microBIOMETER® is involved in various university studies to demonstrate it’s validity and reliability as a soil testing instrument.
Green Country is currently using microBIOMETER® to compare worm castings that are produced with high quality malted barley. They feed malted barley in some of their worm bins and not in others.
Stay tuned! We will post the results of their experiment once it is complete.
Source: Food Web and Soil Health
The graph pictured here from the USDA website depicts the ratio of fungi to bacteria as a characteristic of the type of system it is in. An excerpt from the article:
“Grasslands and agricultural soils usually have bacterial-dominated food webs – that is, most biomass is in the form of bacteria. Highly productive agricultural soils tend to have ratios of fungal to bacterial biomass near 1:1 or somewhat less. Forests tend to have fungal-dominated food webs. The ratio of fungal to bacterial biomass may be 5:1 to 10:1 in a deciduous forest and 100:1 to 1000:1 in a coniferous forest.”
If you are measuring soil attached to the roots colonized by mycorrhizal fungi, your ratios should be much higher than is shown for agricultural soil. Also the saprophytic fungi population increases when there is a lot of litter for digestion, so you would expect to see different ratios at different times of the year and under different conditions.
The graph pictured below based on USDA website information shows the expected fungal to bacterial ratio for various plants.
Please visit our Using the Fungal to Bacterial Ratio with microBIOMETER® on YouTube for more information on fungal to bacterial analysis.
