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]

Nitrogen fertilizer study at Ursinus College

University study demonstrates legumes are more efficient at improving soil MBC than grasses

Under the direction of Assistant Professor Denise Finney, Kylie Cherneskie, biology student at Ursinus College, conducted an experiment on the impacts of nitrogen fertilizer addition on soil microbial communities. Kylie measured microbial responses using microBIOMETER®.

Click here to view the finished poster presentation. If you would like to incorporate microBIOMETER® into your classroom studies/academic research, we offer a selection of Academia Classroom Kits.

Study shows microBIOMETER® correlates with Chloroform Fumigation Extraction

Calibration of microBIOMETER® to units of µg microbial carbon / gram soil

The gold standard of laboratory soil microbial biomass testing is Chloroform Fumigation and Extraction (CFE). The multiple steps, time, and labor involved with CFE require pricing at up to $500 per sample. CFE works by comparing the difference of chemically extractable carbon between two portions of a soil sample: One that has been treated to break open microbial cell membranes and expose the carbon-containing biological molecules to extraction, and one that has not. The difference in carbon for the two portions is reported as microbial biomass carbon (MBC), in units of µg C / g soil.

microBIOMETER® is calibrated to the same units by a different method. Estimates of bacterial dry mass converge at around one trillionth (1×10-12) of a gram (1 pg) for a 1 µm bacterium. We measured the area of microbes in known volumes of microBIOMETER® extract (both by manual counting on a hemocytometer and by digital analysis of micrographs) and calculated total microbial mass, which was then converted to µg / g for the whole 0.5 ml sample of soil in the extract. We found that on average, 0.5 ml of soil weighs 0.6 g when fully dried, independent of starting moisture content. The 1 pg dry mass per bacterium is 50% carbon, so we also had to account for that in our calibration.

Here’s an example of the conversion.

Let’s say that in 1×10-8 liter (10 nl) of microBIOMETER® extract we measured 240 µm2 of microbes. 240 µm2 = 240 bacteria equivalents (BE). 240 BE x 1×10-12 g per BE = 240×10-12 g of dry microbes. The volume of original extract is 10 ml (1 x 10-2 liter), and 10 nl of microscopically examined extract represents 1×10-8/1×10-2 = 1×10-6 of the total mass of the microbes in the extract. So 240×10-12 g microbes / 1×10-6 = 240 x 10-6 g microbes in the whole extract. 50% of the 240 x 10-6 g of microbes is carbon, so we have 120 x 10-6 g microbial carbon. We started with 0.5 ml = 0.6 grams of dried soil in the extraction process, therefore 120 x 10-6 g microbial carbon / 0.6 g soil = 200 x 10-6 g microbial carbon / gram soil, or 200 µg microbial carbon / gram soil.

While we arrived at µg microbial carbon / gram soil through a different method than CFE, it turns out our methods are on par with the CFE test. We compared measurements of µg carbon / gram soil via CFE and microBIOMETER® from 28 soils from across the U.S.

The slope of ~1 of the regression line indicates our units are on par with CFE, and the 94% correlation indicates that users can be confident that the $10 or less microBIOMETER® test gives results as accurate and informative as one priced $500.

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.

Community gardening with microBIOMETER®

Informal science education is a key for community engagement and healthy gardening. Community gardening  brings numerous benefits such as fresh produce, therapy, physical exercise, reduction in grocery bills, improvement of mood among many others.

“Last weekend I had the privilege to teach community gardeners on the importance of soil testing side by side with my very first student at NYBG Adult Education program (class 2015). Dr. Joan Basile is a clinical psychologist who has developed her own horticulture therapy program incorporating soil knowledge brining therapy & soil science & gardening together.” – Dr. Anna Paltseva,  soil_expert.

“While the microBIOMETER® results showed there is room for improvement, the result from last year’s beds also proved that composting and mulching practices are paying off in increased soil life. This means that sandy soil will gradually be able to hold nutrients better and better!” – Dr. Basile

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.



Soil Carbon Q & A with Dr. Judy

soil carbon

We recently received the following questions from one of our customers and below are the responses from Dr. Fitzpatrick.

Part of my research is surrounding the soil organic carbon results we attained from microBIOMETER®, and I am wondering if someone from your team could provide more information on what this means relative to total organic carbon (TOC) in a sample and if they are comparable?

The literature shows a strong correlation between available organic carbon and microbial biomass carbon (MBC). Since your compost is not soil, the available organic carbon in your sample would be TOC and would correlate. MBC by microBIOMETER® is even better than that: a big number tells you that you have carbon and all the nutrients needed by microbes and plants.

Since MBC has correlations to TOC is there a formula or percentage to convert MBC to TOC? Or approximately how much MBC makes up a TOC number?

There is no formula to correlate TOC with MBC. TOC includes carbon that we consider stored as well as carbon that is easily available to microbes. Increasing easily available carbon for example by applying compost will increase microbes and eventually increase TOC, but as microbes rarely exceed 1% of TOC, it would have little effect on TOC short term. In long term stable systems we see a correlation but the correlation is not the same for example in forest as in agriculture as the capacity to store TOC is different soils under different conditions. In studying the effect of long term (40 years) different management systems at U. of TN on MBC and TOC, MBC by microBIOMETER® correlated with the TOC demonstrating the effectiveness of sustainable practice on increasing TOC and the positive correlation with MBC levels.

Does a high MBC usually mean a higher F:B ratio? And if so, could we draw any conclusions about carbon sequestration capabilities from that?

Generally as the MBC increases there is an increase in fungi. The soil food web is a balanced community. Some communities are more fungal dominated some less, but similar communities tend to have the same F:B ratio. It is generally believed that fungi, especially mycorrhizal fungi, contribute more to carbon sequestration than bacteria. This may be because glomalin is carbon rich and tends to sequester.

To further my understanding of soil/compost mixtures. I performed two microBIOMETER® tests. One test was on “active compost” which is compost in a medium stage of decomposition, and generates some CO2 and another one “finished compost” which is cured, ready for usage, and low CO2 production. However, I found that they had similar amounts of MBC and F:B ratio. Is this normal?

A study with microBIOMETER® at University showed a higher F:B in finished compost. The higher respiration/MBC indicates that your unfinished compost is still being digested — working microbes make more CO2. Holding MBC stable in your finished product is good.


Soil testing update from Brazil

Chiappetta Agricultural Company

We were excited to hear from our long-time customer Marcelo Chiappetta of  Chiappetta Agricultural Company on how his microBIOMETER® testing has been progressing. Below is what he shared with us.

“Here in southern Brazil the past 5 years we’ve been working with biological agriculture and changing the way we see and manage our farm; more and more like an agricultural organism. Taking care of microorganisms, plants, animals and humans and focusing on producing high quality grains.

Fungal and bacterial ratio is fundamental to know how our soil is related to what crop we grow. And now, after starting to brew compost tea and using compost extract, microBIOMETER® is helping us measure and understand the right recipe of carbon and nitrogen related to the amount of fungi that we want to build in our composts before adding to the soil. We see that good microbial biomass along with organic matter is excellent for our soils.

In practical terms, we see biological flowering in crop fields and this is the proof that we are doing a great job with nature. Our soil is our bioreactor, and we need to feed it with the right nutrients. The Brazilian biome is rich on biodiversity and as farmers and soil guardians we have a responsibility to bring life back to our farm again in a sustainable way of producing food.”

Click here to read more on Marcelo’s soil testing.

Improving soil health and carbon content

soil testing carbon
Soil testing

Modern agriculture practices have led to the systematic degradation of the world’s soil and release of carbon into the environment. The effects are increased need for expensive and environmentally dangerous inputs (fertilizers, pesticides, and herbicides), the loss of fertile top soil, decrease in water holding capacity of soil and dangerously high levels of atmospheric carbon.

Farmers, industry, and environmentalists are looking for cost-effective and reliable ways to measure soil health, to assess impacts of progressive changes on soil and harvest management, and to measure carbon in soil. Before microBIOMETER®, growers have traditionally relied on expensive lab testing of soil. Many current methods are technique and individual lab dependent. Therefore, run-to-run and lab-to-lab variation can greatly affect consistency leading to increased variability. Current methods are performed in labs and the soil is aged and changed from the time of collection. Furthermore, lab tests are difficult to use in developing countries as they can cost upwards of $500 per sample. This makes the test prohibitive to some markets and limits the number of times a grower can test their soil.

Our mission at Prolific Earth Sciences is to enable soil stewards all over the world to use mobile technology and our low-cost soil test to assess regenerative soil practices, to improve soil health, and work towards increased soil carbon sequestration. microBIOMETER® equips growers with the data necessary to make decisions on which practices are the most cost-effective. Inputs such as fertilizers are expensive and changes to practice are risky. Monitoring soil microbial biomass inexpensively, in real time, can help a soil steward quickly assess if an input and practice is improving soil health and worth the investment. In other words, assess before you invest! We also envision microBIOMETER® one day being a powerful tool in the measurement and audit of carbon sequestration programs.

microBIOMETER® has been on the market for over 3 years with direct and distributor sales and currently has customers in over 20 countries.

Testing bio fertilizers in Canada

Ralph Lett, head of product development at Acterra, was kind enough to share his microBIOMETER® experience with us. We love hearing the different ways our customers are using our soil test! Please contact us  if you would like to share your soil testing story.

“Thanks for taking an interest in how our company is using microBIOMETER®.

Acterra is a bio stimulant company. We work closely with our sales partner, Bio-Active. Together we capture and solubilize diesel emissions in a fusion tank and then add a beneficial consortium of facultative microbes . This is revolutionary as it allows the farmer to make his own biological fertilizers while he is seeding and/or harvesting.

microBIOMETER® is a handy tool for us to measure the microbial weight of our bio fertilizers when we come in off the fields to refill our tanks . The microbes in our fusion tank reproduce incredibly quickly, much faster than a regular brewing process. If the microbial populations grow too quickly things can get plugged up and can cause problems. This is where microBIOMETER® is incredibly useful. We use it to keep an eye on the populations in our tanks so that if over populations occur we can quickly drain the tank and start over .

We plan to continue working with microBIOMETER® in the future. Our hope is that one day farmers will be able to sit in their tractors and know exactly the microbial bio weight of their biological fertilizers while they are farming their fields.

Never stop innovating !” –  Ralph Lett