David Purdy, Territory Business Manager at John Deere and Soil Health Specialist, utilized the microBIOMETER® soil test in his study titled Assessment of the mircoBIOMETER Soil Biology Test for Agrovista LTD.
Background:
There is an increased level of interest in soil health and a greater demand for more analytical approaches, in particularly for soil biology, for its assessment from farmers and advisors. This short report reviews the use of a recently developed rapid on-site soil microbial carbon testing tool called microBIOMETER® using a replicated 5 year cover crop experiment.
Location:
The experiment was carried out at the location of the Agrovista LTD. trials site is near Lamport in Northamptonshire about 8 miles north of Northampton in the UK. It has a longitude of 52.372234, and latitude of -0.874273. The field site history is of arable farming rotations on a slightly southerly sloping topography.
“The tests, although time consuming, provided an “in field” test that when conducted well seems to suggest it is a reliable, consistent, replicable, and relatively simple test to evaluate soil biological activity.” – David Purdy
Here’s a story from our friends at Kiss the Ground about regenerative southwest wheat farmer Yadi Wang at Oatman Flats Ranch home of Regenerate AZ 2023. He is working on a seemingly impossible mission to transform a degraded oat farm into the first large-scale, regenerative farm in one of the hottest and driest climates in the country, Arizona.
Founded in 2008, Applied Bio-Minerals, Inc. specializes in managing naturally present microbiomes using mixtures of mined minerals.
The company’s operating mode is based on observations, and a close collaboration with the customer. The holistic approach enables farmers to use microbes already present on their farm to their benefit by lowering their inputs and maximizing their revenues, all naturally. As part of the service provided to customers, the company regularly measures progress to ensure the farmer’s goals are met.
Their approach is to examine the entire living soil profile and record its evolution from a baseline set before the application of products. Among the many variables one is essential, the amount of living micro-organisms, and the ratio between bacteria and fungi, at various soil depths.
That is where microBIOMETER® comes in. They have been utilizing the microBIOMETER® soil test in their business since 2020.
“microBIOMETER® is a very convenient tool to have a quick result (in the field) on microbes and allows decisions and adjustments in conducting the field as the season progresses or from one season to the next. Microbial life might sometimes be surprisingly active in depth (here a vineyard). The importance of checking compost quality also underlines the usefulness of the microBIOMETER®” – Herve Bonin, co-founder and managing partner of Applied Bio-Minerals, Inc.
About Applied Bio-Minerals, Inc.
Data from Applied Bio-Minerals, Inc. customer in Virginia
We first had the pleasure of working with Briana Alfaro and Soul Fire Farm in 2021 when they began testing soil with farmers in their network as part of their SARE research project, Soil Carbon Capture for Diverse Farmers; Black, Latinx, Asian, Indigenous and other farmers and farm workers of color take the lead in testing soil carbon sequestration strategies and measurement protocols and disseminate those findings to the farming community in both English and Spanish.
Every two years the Soul Fire Farm team takes a closer look at the soil ecosystem and assesses how healthy their soil is. They do this by performing a series of in-field tests. Long before the western study of soil science, Indigenous communities practiced–and still practice–methods of evaluating soil health using characteristics such as color or the presence of specific plants or insects that tell us something about the system as a whole. On their soil testing days, they count the number of earthworms, perform a slake test to observe aggregate stability, look at soil color as an indicator of organic matter, and use the microBIOMETER® field kit to assess soil biology.
You can learn more in their Guide to In-Field Soil Health Measurement Protocols: How Alive is My Soil (English) & ¿Qué tan vivo está mi suelo? (Español), and by watching their Liberation on Land skill share videos: Soil Carbon part 1, Soil Carbon part 2 & Investigating Soil with an Auger.
Andrew Turnbull is the owner of SouthWest Agronomy Ltd (SWA) located in Tavistock, England. His company offers advisory and consultancy services to golf courses and sports turf facilities.
One issue the company faced was how to prove to their customers that their recommended treatments were actually having a positive influence on the soil microbes. Other than the obvious visual effects of the quality of the playing surface, which can often be open to interpretation, Andrew wanted to prove that other factors have improved performance such as extra or different maintenance operations. Andrew found regular soil microbial analysis to be expensive with only a few laboratories locally performing accurate testing.
“microBIOMETER® changed the game!” – Andrew Turnbull
Now, in addition to comprehensive nutrient and microscopic analysis, the company incorporates regular microbial testing with microBIOMETER® into their program. This enables them to give their clients confidence that they are implementing changes that not only have a positive visual effect, but a measurable and direct one as well.
About SouthWest Agronomy Ltd (SWA).SWA focuses on the little understood aspect of how turfgrass plants interact with the rootzone biology and how the plant’s metabolism is affected by biotic and abiotic stresses. When a turfgrass plant is healthy it excretes carbohydrates, proteins and other exudates that feed microbes. This increases mineralization of nutrients, enhances disease protection, and causes organic matter recycling. SWA’s Bio Nutrition Program restores the balance between the plant and soil microbes which is lost when turfgrass management relies on chemical fertilizers, and/or is under continual stress from maintenance operations, and/or has less than optimum environmental conditions (e.g. heat, cold, shade), and regular use by players.
Kenley Mitchell, a 5th grader at Sargent Elementary School, utilized microBIOMETER® in her science fair project titled “Getting Dirty: Does Soil Affect a Dog’s Microbiome?” Kenley won first prize in her category and received the overall best project award for the San Luis Valley Regional in Alamosa, CO!
Project Abstract:
For my project, I tested a dog’s microbiome and compared it to the health of the dog’s soil. I also looked at the time the dog spends in the soil. I ran two samples. The first sample was a stool sample. The second sample was a soil sample. Both were taken at the same time. I tested dogs that are in the city vs. country dogs. I found out that farm dogs have a healthier microbiome, but city dogs have healthier soil. The farm dogs’ average microbial biomass in the soil is 221.0 ug C/g. The city dogs’ average microbial biomass in the soil is 273.4 ug C/g. Farm dogs average for F% is 20%. City dogs average for F% is 32%. Farm dogs average for B% is 80%. City dogs average for B% is 68%. The farm dogs were outside in the soil for longer periods of time. The farm dogs might be healthier due to spending more time in the soil.
Francis Lawton an 8th grader at St. Timothy School in Los Angeles, CA utilized microBIOMETER® in his science fair project titled “The Effect of Greywater on Plant Growth, Soil Microbial Biomass Carbon, and Soil Fungi to Bacteria Ratio. Francis took first prize at the fair and moved on to the Los Angeles County Science & Engineering Fair where he placed 3rd in his category of Ecology. He also received a special award from USAID (U.S. Agency for International Development). Francis then took part in the California State Science & Engineering Fair in the category of Earth & Environment (Air/Water) and placed 2nd!
Have a science fair project coming up and would like to incorporate microBIOMETER®? Please contact us!
Project Abstract:
This project was designed to find out if greywater and treated greywater can safely hydrate plants, and promote plant growth, just as well as tap water. I live in drought-prone California and it’s important to find different ways of conserving water. My experiment tested the watering of grass pots with three different types of water (independent variable): Tap water, Greywater, and Greywater treated with Activated Charcoal. Over the course of 8 weeks, I measured plant growth, soil Microbial Biomass Carbon (MBC) levels and soil Fungi to Bacteria (F:B) ratio (dependent variables). Many controlled variables ensured a valid experiment. I hypothesized that each of the water types would result in the same growth rate, soil MBC and soil F:B ratio. My hypothesis, however, was incorrect. Greywater resulted in stunted growth and spiked the F:B soil ratio so high that the pot sprouted 13 fungi heads. Tap water and Treated Greywater, however, were equally good in terms of healthy plant growth and both pots had the two best average F:B ratios closest to 1:1 (which is the best ratio for grasses). Neither of these pots produced fungi. Soil carbon levels (MBC) fluctuated for all three plants, however each plant maintained an “Excellent” level. This indicated that each water type was fine for watering grass if you don’t mind stunted grass growth and some fungi in your lawn. My experiment also proved that Activated Charcoal effectively “adsorbs” chemicals in greywater that alter a soil’s F:B ratio.
Amy Gardner of Kalispell, Montana serves farmers in the Flathead Valley as an agronomy coach through her business, Lower Valley Consulting Inc.
Amy has been scouting soil health trials as part of gathering third-party research for the company AgriGro. Farmers have been applying AgriGro’s prebiotic technology to boost soil health and in turn grow more productive and nutrient-rich crops. Amy uses microBIOMETER® to help compare soil microbiology in the control strips and where the prebiotics have been applied. Other data points collected for the trials have included plant counts, soil moisture, tissue tests, soil tests, vegetative cover percentages, GreenSeeker readings, and root, plant mass and health observations. So far 14 soil health trials have been performed in Montana and Idaho. More trials are scheduled for the Summer of 2023.
Amy Gardner was born and raised in Kalispell, MT. She has her BSc in Agricultural Education from Montana State University. Amy is a Certified Crop Advisor, as well as a Precision Ag Specialist, through the American Society of Agronomy. She is passionate about helping growers build healthy soils to produce high yielding and nutrient-rich crops through precision management. Her and her husband enjoy the Montana outdoors with their 5 boys.
The microBIOMETER® was developed with the need in mind to deliver a device that could be manufactured very reasonably so that it could service the whole world. For over 50 years scientists have known that microbes are the best indicator of soil health. One of the common methods used for determining soil microbial biomass is the Chloroform Fumigation Extraction (CFE) test. However, being a costly lab-based test makes it an unattainable option for many. Another method that’s often used to assess soil microbial communities is microscopy. While microscopy is one of the best ways to assess soil microbes, microscopes can be expensive, are often too large and heavy to bring into the field, and are not necessarily easy to use or easily accessible for growers around the world. In 2014, Dr. Fitzpatrick began developing the microBIOMETER® to address these shortcomings.
The microBIOMETER® was designed to detect bacteria and fungi by their pigmentation on a specially designed membrane. An extraction powder was developed that contains different salts, which, combined with precise whisking, separates the microbes from the soil particles. The addition of this extraction powder also helps to precipitate the soil so that the microbes stay suspended as the soil precipitates to the bottom of the test tube.
Once the microbes are separated from the soil, they can be detected by spectrophotometry. However, like a microscope, a spectrophotometer is both expensive and too large to use in the field. The solution, in keeping with the goal of manufacturing a very cost-effective device, was to make it a lateral flow membrane. Almost all medical devices do a vertical flow, but a vertical flow has many technical problems. In a vertical flow, different types of membranes are put together and then a clamshell type device is used to press it down, but this pressure then has to be regulated. And Dr. Fitzpatrick, having worked with many clamshell devices, knew this method caused a great deal of seepage around the outside. A lateral flow, on the other hand, is more rapid than a vertical flow which allows the sample to be put on more rapidly than you can when you’re using a vertical flow device. The flatness of the device is important as well. Most other devices that are vertical have a rim around the area where the membrane is which is called a sample well. If you look down the well you cannot see the bottom because the well walls are casting a shadow. But microBIOMETER® is flat, therefore, a shadow does not pose a problem.
To perform the test, three drops are applied to the membrane in the test card. The microBIOMETER® membrane was carefully chosen so that it would not bind any of the common pigments you might find floating in soil. It only collects microbes on the surface of this membrane. The membrane also whisks away the liquid and traps the microbes on the surface. The color that it gives to the membrane can be compared to a grayscale, which tells you that the intensity of the color, not the color itself. The intensity of the color correlates with the quantity of microbes you have. Just like with the colorimeter or spectrophotometer, the intensity of the color is linearly related to the concentration of microbes. Dr. Fitzpatrick came up with this grayscale idea while thinking about a quilting secret. Quilters want to make sure they not only have different colors but have different intensities of color as well. Therefore, we’re not just measuring color but also measuring the intensity of the color.
The next step in the development was to figure out how to read the test cards. In the early version of the microBIOMETER®, a red filter with a grayscale was used, turning it monochromatic. A piece of red cellophane was put over the grayscale in the sample window and the results were determined by how dark the center was. This earlier version of microBIOMETER® is still being used by customers who are non-tech users.
At this point, the test could be read visually but it lacked precision, and data storage and tracking capability. For this, it was decided a phone app was needed. One of the barriers to lab testing in developing countries is cost, but another is infrastructure. However, cell phones are ubiquitous. If an app to read the test cards and store the data was created, soil stewards all over the world would have the ability to track soil health over time and assess their management practices while making changes in real time.
The challenge to the cell phone is that cell phones have a camera and manufacturers utilize different software. Therefore, the image viewed isn’t raw and overcoming the differences between various phones becomes necessary. The microBIOMETER® does that with the monochromatic grayscale backing. This in essence “tricks” all phones to be in the same range in their software and white balance. The issue of different color temperatures was also encountered. When you’re out in the sun on a cloudy day or you’re in the shade on a sunny day that light is extremely blue. When you’re sitting in your living room and you have a 60-watt light bulb, that light is yellow/red. And if you’re at the office with a fluorescent light that light turns out to be white -where red, green, and blue are all equal. Therefore, accounting for differences not only in cell phones but in ambient lighting conditions became important as well.
This stage of test development consisted of vigorous testing and a good amount of trial and error. The process involved running around with a test card from light source to light source with five or six different phones making sure the readings were consistent. By utilizing the camera’s flash in conjunction with a monochromatic backing, the images between phones became uniform. Once the patented algorithm that compensated for differences in light color and intensity and phone software was finalized, in 2018, the microBIOMETER® was released to market.
A few years later, in 2020, Dr. Fitzpatrick and Dr. Trexler tossed around the idea of adding another soil test to the microBIOMETER® platform; the fungal to bacterial ratio. During one of these discussions, Dr. Trexler inquired if there was a way to use size to differentiate bacteria and fungi. As a microbiologist, Dr. Fitzpatrick knew that bacteria are much smaller than fungi and therefore could be differentiated based on size. Dr. Trexler then wrote software that could detect and pick out the bacteria and fungi. It was discovered that when looking at a fungal to bacterial ratio on the microscope, a slight change in the color was evident; fungi are a very, very slightly different color than bacteria. There was a correlation between the color of the sample and the fungal to bacterial ratio that was detected microscopically, which turned out to be a groundbreaking discovery. After trying various methods for determining the fungal to bacterial ratio by color, it turned out cell phone cameras had the ability to pick up the difference. This discovery led to the fungal to bacterial ratio data being added to the microBIOMETER® app.
The following year, another exciting feature was added to the platform; Project Management (PM). A big advantage of reading results with a cell phone is that the data can be stored on the cloud. When the app was first written, there were a few different data fields for each sample. There was crop quality, crop type, soil class, and a couple other generic fields. It was soon realized that people using the test were likely more knowledgeable about what data and metrics assisted with farming. So, the app was updated to allow users to create their own fields based on their needs. This development was the release of Project Management (PM). Now, users can have as many fields of data as they want and it’s completely adjustable. Another benefit of PM is it lets users create a project and anyone on the team can upload their test results to the project. Before PM, everyone’s samples were on their own phone and in their cloud account. Now all the samples, regardless of who performed the test, are in one place and can be easily downloaded for analysis. Users can create as many projects as they want to keep trials separate from each other, but with all the data aggregated. There is one microBIOMETER® customer who currently has 20 different projects that match up with each of the properties they manage.
microBIOMETER® allows users to quickly determine if they are achieving the improvements they are looking for; track soil microbial activity over time and see how it varies with practice in order to assess what is working and what is not. With an innovative, yet inexpensive soil test like microBIOMETER®, $7 to $14 compared to much more expensive tests, growers can sample more per acre, allowing them to acquire a better understanding of their crops. With the ease of multiple sampling combined with data storage, users can view year over year and season over season results to see if their microbiology is increasing and if their soil health is increasing as a result.
It is important that the microbiology increases because there’s an incredibly high correlation between soil biology and soil health. We know that as microbial activity increases, so does the water holding capacity of the soil. It also makes crops more resistant to excess water – which can lead to erosion. Soil microbes build soil structure, which mitigates drought as well as flooding risk because it improves the texture of the soil. Microbes make a glue-like substance which enables them to stick to the soil. This stickiness remains after the microbes die and causes the soil to become clumpy. These clumps allow the soil to hold more oxygen, as it provides more aeration. Growers can improve the amount of carbon in their soil since the stored carbon in your soil is the bodies of dead microbes. When a microBIOMETER® soil test is performed, you’re looking at a snapshot of the microbes. They’re constantly turning over and they are food for other predators in the ecosystem. But that turnover demonstrates that you have a large number of microbes and that the entire ecosystem is being fed.
When you feed the soil ecosystem – from microbes to earthworms to mammals – that’s when you achieve the healthiest soil. Many creative and innovative practices are being developed that understand that healthy soil is part of a healthy system. The start is a healthy microbial ecosystem and microBIOMETER® gives you a glimpse into that very, very quickly. There’s nothing else like it.
This article is based on the video The History and Science behind microBIOMETER®
Your soil is a unique mixture of sand, silt, clay, and organic matter. The particular make-up of your soil determines its color, texture, and nutrient storage capacity. Knowing your soil’s texture and nutrient storage capacity is important when deciding how much and how often to feed and water your plants. Some nutrients are more easily stored and attached to soil particles compared to others due to the strength of their electrostatic bond. As the famous saying goes, opposites attract – and this holds true in soil as well.
Mineral nutrients such as calcium, potassium, ammonium, and magnesium are called cations because they have positively charged ions. The ability to attract and hold onto these positive cations comes from negatively charged soil particles, called colloids, found in organic matter and clay. It’s important for these nutrient cations to attach to the soil colloids so that they can be supplied to the plant when needed. If the nutrient cations don’t attach, they’ll easily leach out during a time of rain.
However, like in most fair economic systems, the plant can’t just take these nutrients from the soil without giving something in return. For example, if a plant needs some potassium, it will have to exchange one of its cations for the soil’s potassium cation. Thankfully, plants produce hydrogen cations that they can use for this exchange. The soil accepts these hydrogen cations because they’ll be used in photosynthesis and respiration.
This exchange is easier than others because both hydrogen and potassium have a positive charge of +1. Calcium, on the other hand, has a positive charge of +2 and therefore requires two hydrogen cations for its exchange, making the process a bit harder. The higher the positive charge on the cation, the harder it becomes to exchange between the soil and plant. However, the bond between the higher charged cations and the soil is stronger than that of the lower charged cations. This exchange process occurs on the plant’s root hairs, which is why it’s important to have a strong, healthy root system for your plants. The amount of cations that can be retained within the soil is called Cation Exchange Capacity (CEC) Source: Jagdish Patel.
Understanding the CEC of your soil is important due to its strong influence on nutrient and water retention and availability, soil structure stability, and soil pH and fertility. Adding organic matter to your soil is one of the most effective ways of increasing your soil’s CEC and increasing the amount of exchange sites. The more exchange sites, the greater the ability for nutrients to be retained within the soil. Having a high CEC not only reduces leaching of nutrients, but also helps buffer your soil against pH changes.
While it’s very beneficial to have a high CEC in your soil, soils with a low CEC can still be managed successfully – they just have different requirements than soils with a high CEC. Low CEC soils need small, but frequent intakes of nutrients and water, rather than large, infrequent intakes due to their fewer exchange sites. Less exchange sites means less space to hold onto the incoming nutrients. And as microbes are actively involved in transforming nutrients to plant-available forms, it’s imperative to maintain suitable soil conditions for optimal microbial activity.
Many soil testing labs will provide you with your CEC levels which are reported in units of milli-equivalents per 100 grams of soil (meq/100 g). Average levels range from less than 10 for sandy soils and 50-100 for organic rich soils. Pure organic matter has a level of 200-400. Generally, 1-10 is considered low while 10-50 is considered moderate to high.
