Soil research in Kenya with microBIOMETER®

Janet Atandi, a nematology PhD student in Kenya, is currently working on an assessment of banana fiber paper on soil health as part of a Wrap and Plant technology study. In brief, she is testing the long-term effect of using modified banana fiber paper to manage plant-parasitic nematodes and its impact on the beneficial soil microbial communities.

The banana fiber paper is used as an organic carrier for either ultra-low dosages of nematicides (abamectin and fluopyram) or microbial antagonists (Trichoderma spp.) and is to be compared to unmodified paper.

This study is being conducted using potatoes and green peas as the test crops over five consecutive seasons. With the aid of a microBIOMETER® test kit, Janet will be able to assess the impact of the paper on the soil microbial biomass and thus will be able to determine whether the banana paper is effective or detrimental to soil health.

Wrap and Plant technology sources:
NC State explores promising pest-control strategy with high-impact potential for sub-Saharan Africa
Banana’s Waste, potatoes gain
Potato farmers conquer a devastating worm—with paper made from bananas]

Things you need to know about the Fungal to Bacterial Ratio (F:B)

    • microBIOMETER® is the only non-laboratory test for F:B.
    • The methods of measuring F:B ratio give very different values 1-11. The Gold Standard for estimating fungal biomass is microscopy, which calculates fungal biovolume.  Note that microBIOMETER® detects the same range as microscopy- not surprising as it was validated by correlation with microscopy.  For review of these measures see Appendix 1.  For measuring progress, stick with one method.
  • Different methods measure different fungal and bacterial populations.  The chart below, adapted from Wang et al review of 192 different F:B ratios, illustrates how three different methods came up with three different F:B ratios for Forest, Farmland and Grassland.  Note that microBIOMETER® correlates well with the gold standard, microscopy. By plate culture, forest F:B is about 1/3 that of farmland, whereas PLFA forest F:B is slightly higher, and microscopy and microBIOMETER® forest F:B are 10 times higher than farmland.
  • In addition, F:B ratios are strongly affected by the following variables:
    • Crop type – forest is typically higher than agricultural,
    • AMF – soil of crops that are colonized by AMF have higher F:B
    • pH – fungi tend to increase at lower pH
    • Sampling site – the rhizosphere of AMF colonized plants has higher F:B
    • fertilizer and litter composition – high nitrogen lowers F:B, organic fertilizer regimens increase F:B as well as MBC.
  • microBIOMETER® cloud data demonstrates an F:B range of 0-13.5. Note that as the literature predicts, generally the F:B correlates well with MBC.  The cloud data portrayed is not identified by user and so we do not have information on the type of soil or crop.  From conversations with users, we believe that about 2000 ug MBC/gm soil is the highest seen in agricultural soil, while engineered soils can read higher.

    References

     

    1. Anderson, J.P. and Domsch, K.H., 1978. A physiological method for the quantitative measurement of microbial biomass in soils. Soil biology and biochemistry10(3), pp.215-221.
    2. Bååth, E. and Anderson, T.H., 2003. Comparison of soil fungal/bacterial ratios in a pH gradient using physiological and PLFA-based techniques. Soil Biology and Biochemistry35(7), pp.955-963.
    3. Bailey, V.L., Smith, J.L. and Bolton Jr, H., 2002. Fungal-to-bacterial ratios in soils investigated for enhanced C sequestration. Soil Biology and Biochemistry34(7), pp.997-1007.
    4. Bardgett, R.D. and McAlister, E., 1999. The measurement of soil fungal: bacterial biomass ratios as an indicator of ecosystem self-regulation in temperate meadow grasslands. Biology and Fertility of Soils29(3), pp.282-290.
    5. De Vries, F.T., Hoffland, E., van Eekeren, N., Brussaard, L. and Bloem, J., 2006. Fungal/bacterial ratios in grasslands with contrasting nitrogen management. Soil Biology and Biochemistry38(8), pp.2092-2103.
    6. Johnson, D.C., 2017. The influence of soil microbial community structure on carbon and nitrogen partitioning in plant/soil ecosystems(No. e2841v1). PeerJ Preprints.
    7. Khan, K.S., Mack, R., Castillo, X., Kaiser, M. and Joergensen, R.G., 2016. Microbial biomass, fungal and bacterial residues, and their relationships to the soil organic matter C/N/P/S ratios. Geoderma, 271, pp.115-123.
    8. Malik, A.A., Chowdhury, S., Schlager, V., Oliver, A., Puissant, J., Vazquez, P.G., Jehmlich, N., von Bergen, M., Griffiths, R.I. and Gleixner, G., 2016. Soil fungal: bacterial ratios are linked to altered carbon cycling. Frontiers in Microbiology7, p.1247
    9. Soares, M. and Rousk, J., 2019. Microbial growth and carbon use efficiency in soil: links to fungal-bacterial dominance, SOC-quality and stoichiometry. Soil Biology and Biochemistry, 131, pp.195-205.
    10. Wallenstein, M.D., McNulty, S., Fernandez, I.J., Boggs, J. and Schlesinger, W.H., 2006. Nitrogen fertilization decreases forest soil fungal and bacterial biomass in three long-term experiments. Forest Ecology and Management222(1-3), pp.459-468.
    11. Wang, X., Zhang, W., Shao, Y., Zhao, J., Zhou, L., Zou, X. and Fu, S., 2019. Fungi to bacteria ratio: Historical misinterpretations and potential implications. Acta Oecologica, 95,

     

     

microBIOMETER® testing for soil health and yield stability

Nature article reports that microbial biomass estimates by microBIOMETER® correlates with soil health and yield stability.

The microBIOMETER® soil test was used to report microbial biomass in a recent Nature publication*. Scientists Dr. Judith Fitzpatrick and Dr. Brady Trexler of microBIOMETER® collaborated with a University of Tennessee team headed by Dr. Amin Nouri. The team evaluated the effects on soil health and yield stability of 39 different methods of raising cotton over 29 years. The conditions tested included till, no-till, various cover crops and different levels of nitrogen fertilization.

The study found that the major impacts on yield were very dry or wet conditions, and low or high temperatures. The deleterious effects of these weather extremes on yield were mitigated by regenerative agricultural practices which resulted in adequate soil, C, N, soil structure and microbial biomass.

Conservation agriculture increases the soil resilience and cotton yield stability in climate extremes of the southeast US

*Nouri, A., Yoder, D.C., Raji, M., Ceylan, S., Jagadamma, S., Lee, J., Walker, F.R., Yin, X., Fitzpatrick, J., Trexler, B. and Arelli, P., 2021. Conservation agriculture increases the soil resilience and cotton yield stability in climate extremes of the southeast US. Communications Earth & Environment, 2(1), pp.1-12.

microBIOMETER® Soil Testing in France

The Biospheres, working through the CDA*,  accompanies and trains farmers/agricultural companies in the agroecological transition based on a soil conservation approach. The group is also working on applied research projects and therefore on trials under real farming conditions in which they evaluate the impact of certain changes in practices on different indicators (biological, chemical, physical, economic).

“One of our primary objectives is that farmers succeed in putting biology back into their soils to ensure their natural fertility. We are therefore very interested in everything that lives in the soil, from earthworms and microarthropods to microorganisms (bacteria, fungi, nematodes). For us, microbial biomass is one of the most important indicators that help us understand soil biology. Fungal to bacterial ratio, which is a less documented indicator for the moment, remains interesting to observe in certain situations and is the object of real research by our R&D team to understand how best to interpret it.

We have been using microBIOMETER® for 8 months now to test the soil in different projects in our panel of biological indicators. microBIOMETER® provides us with quick and easy results on microbial biomass and F:B ratio which is a real plus for us. We can perform tests directly in the field and present the results to the farmers. Moreover, the affordable price of the analysis allows us to perform soil biology tests in projects where we had no affordable way to do so before.”

*CDA, Centre de Développement de l’Agroécologie, are affiliates dedicated to R&D and advisory.

 

 

microBIOMETER® in University of Michigan Research Study

Joshua Mikesell utilized microBIOMETER® in a University of Michigan Intern Student Program last fall for his 501(c)3 compost business Happy Coast.  The goal of his compost business is to seek out organic waste products and develop ways to reduce and recycle these materials. In preparation for the study, Joshua created multiple controlled scenarios to test biomass in certain situations and in several types of compost.

For the project, they sorted through food waste obtained from local businesses and developed a process and ingredient list to produce their own organic fertilizer. microBIOMETER® was used to perform the initial tests. Then after their pellet applications was used again to determine effectiveness.

The University of Michigan was so impressed with Joshua’s study they now want to send him as many students as possible to continue this work.

Click here to read the entire report as well as view all the microBIOMETER® data collected.

Soil Testing at the University of Louisiana at Lafayette

soil testing
University of Louisiana at Lafayette

Last semester Soil Science and Environmental Pedology students under a supervision of Dr. Anna Paltseva [annapaltseva.com] conducted a soil microbial experiment on campus of University of Louisiana at Lafayette. First, each of the group of students collected different samples. Samples were collected from lawn, vegetable containers, around tree pits, and a native plants garden. The soil samples were analyzed in accordance with the provided procedure, which is simple and fast. The microBIOMETER® app tested the samples and gave each of the readings. The readings were in microbial biomass expressed in microbial-carbon per gram of soil (ug/g) and fungal to bacteria ratio F:B, F% and B%.

The vegetable container and samples from the tree pits showed the highest range of 400 – 800 ug/g. This is due to high organic matter content. The low results from the lawns may have been due to limited microbiological diversity due to monoculture of grasses grown. The areas close to the water bodies (culvert, pond, etc.) may have been lower due to organic matter washing away over time. All the samples were predominantly rich in bacterial population over fungal.

“microBIOMETER® is a very efficient and time saving tool. It can be used by scientists, farmers, or a gardener in learning the microbial health of their soil. This testing process is also very non-invasive, and thus having a lesser negative environmental impact compared to traditional testing. One of the students said, It was pretty cool using an app to analyze soil. I want to know how it works since it all felt like magic.” – Dr. Anna Paltseva

Click here to view the student’s video.

Order a microBIOMETER® Academia Kit for soil testing in your classroom! 

If you are interested in Dr. Paltseva’s research or would like to learn more about urban soils, please follow her on Instagram.

soil testing
Microbial Biomass Chart
  • The chart above and text was prepared by Blair Miller.  It is based on the microBIOMETER® Test conducted on University of Louisiana at Lafayette campus.
  • Video prepared by Ethan Trahan demonstrating how students use microBIOMETER® Test on University of Louisiana at Lafayette campus.
  • Students appearing in the video from the School of Geoscience at the University of Louisiana at Lafayette include: Tristen Ashworth, Blair Miller, Sydney Renard, Austin Delaney, Andrew Womble, Susmita Shrestha, Isabelle Ordonez, Sherry Pinell, Kenneth Despain, and Ashton Young.

 

Microbial Biomass vs. Microbial Respiration

What is the difference between microbial biomass (MB) and microbial respiration rate (RR) ?

Both parameters are used to assess soil microbial health. The respiration assay measures the amount of carbon dioxide produced by the microbes in a given weight of soil. The soil is dried and then rewetted and put in an airtight jar that allows measurement of the amount of CO2 produced over 24 hours. The CO2 is produced by the activity of the microbes in the rewetted soil. Between 20% and 70% of the microbes die during drying but their dead bodies often provide nutrition for the survivors to use and regrow the population to its original level.

Respiration reflects the regrowing work that is being done. The respiration level is often mistakenly believed to predict microbial biomass (MB), but it does not. Microbes in a low pH or toxic soil have to work harder, therefore, their respiration rate is higher, just as your respiration rate in the gym is higher than when you are watching TV. Outside of the U.S. the respiration rate (RR) is only considered in relation to MB and this q-value RR/MB is used to determine the level of stress in a soil. If RR is high for the MB, the soil is in trouble.

MB, as measured by microBIOMETER®, correlates with chloroform fumigation—always and microscopic evaluation of soil. It is an excellent predictor of soil health because the size of the microbial population correlates with the nutrition available in the soil. If the soil is deficient in carbon, nitrogen, phosphorus or any other mineral, or contains toxins, MB will be low. In fact, MB is low in any soil that is compacted, has a low pH or is overly dry, because microbes need oxygen and moisture and the correct pH for enzymatic activity.

In nature, the plant uses 30% of its food production to feed a microbial population that will mine the soil for the N, P, K, S etc. that it needs. Interestingly MB is low in soil treated with high levels of mineral fertilizers; researchers have shown that the stimulus for the plant to grow a microbial population is its need for nitrogen and phosphorus. If these are artificially supplied the plant is not stimulated to feed the microbes that usually provide these nutrients to the plant. And since the microbes are at least half of the immune system of the plant, you now need lots of pesticides to protect the plant.

microBIOMETER® at Penn State University.

Left: “Intensive” section. Right: “Extensive” section

We began offering microBIOMETER® Academia Classroom Kits  last year and are excited with the interest we have received so far from universities, high schools and other academic institutions in the U.S. and abroad. Professors are utilizing our soil test to introduce their students to the world of microbes and soil health.

Mary Ann Bruns, Professor of Soil Microbiology at Penn State University  recently shared how students in her Soil Ecology class used microBIOMETER® to analyze microbial biomass in the 10-year-old Green Roof Medium of the Forest Resources Building on campus.

Students took composite samples from the “intensive” section (where rooting medium was originally 12 inches in depth) and the adjacent “extensive” section (depth of 4 inches). Samples were taken next to the blue fescue plants in both sections.

Having a deeper layer of growth medium provides more water and nutrients for plants, so the hypothesis was that samples from intensive (healthier) areas would have higher MBC than those from extensive (dried out) areas. Average depths were 7.1 and 3.8 inches, respectively, in intensive and extensive areas. Average MBC for the two areas were 253 and 159 micrograms per gram medium, respectively. Click here to read the full report.

A special thank you to Mary Ann and her students for sharing their research, data and photos! If you would like to share your student’s microBIOMETER® research in our newsletter or learn more about our Academia Classroom Kits, please contact us.

From left to right: Penn State students Tyler Gryskevicz, Amanda Grube and Jason Ben Legayada.

Soil research using microBIOMETER®

In the spring and early summer of 2020, the Nutrient Management Spear Program at Cornell University conducted a soil survey of yield-stability based management zones on a New York dairy farm.

Ben Lehman, research assistant in the Nutrient Management Spear Program at Cornell University, completed a study on the Within- Field Variability of Soil Characteristics and Corn Yield Stability on a New York Dairy Farm.

Ben utilized microBIOMETER® in his research to determine the microbial biomass of the soil samples.

This study was presented at the 2020 American Society of Agronomy Annual Meeting.

Source: Cornell Center for Materials Research

microBIOMETER® collaborates with university soil study

Earthworms recover from Roundup exposure

The effect of various Roundup formulations and microplastics on soil.

Dr. Sharon Pochron and her students at Stonybrook University in New York have been using microBIOMETER® for two years. Dr. Pochron studies the effect of various Roundup formulations and microplastics on soil microbes and soil invertebrates.

Her most recent publication (See Figure 2) shows microbial biomass increasing on day 7 in both the Roundup treated and untreated soils – the 0 line depicts the microbial biomass on day 0. This increase is probably due to the soil microbes responding to rewetting. By day 14 the microbial biomass in the uncontaminated soil is back to baseline, but the Roundup treated soil has dropped well below baseline. By day 21 both soils have returned to baseline. This study shows only total microbial biomass recovery, but there is evidence that Roundup can affect microbial composition.

Source: Earthworms (Eisenia fetida) recover from Roundup® exposure. Pochron et al., 2021 Applied Soil Ecology. 158: 103793.

Prolific Earth Sciences is supporting research at various universities. Feel free to contact us to discuss your project and how we can assist.