Building the Microbial Bridge for Soil Health

By Gary Zimmer and Leilani Zimmer Durand

The root zone around plants, known as the rhizosphere, is an area of intense activity in the soil. It’s a lot like the snack stand at the state fair on a hot day. Everyone is crowding around trying to get to the cold drinks, funnel cakes and hot dogs. Snacks are being sold as quickly as the workers can make them. In return, the snack stand is bringing in a lot of cash.

While the snack stand exchanges food for money, plant roots feed nearby microbes in exchange for plant nutrients. The roots put sugars down into the soil, creating an area of crowded, busy bacterial feeding in the rhizosphere, and exchange that microbial food for nutrients the plant needs but would otherwise have a hard time accessing.

We tend to think that plants photosynthesize entirely for their own metabolism, but in truth plants spend a good portion of their energy feeding soil life.

corn roots
Corn roots with lots of root exudates and soil sticking to the roots.

Plants fix sugars through photosynthesis, and while 55 to 75 percent of those sugars support plant growth, reproduction and defense from pests, the rest goes into the soil through the roots to feed the soil biology. This isn’t a waste of energy by the plants.

Bruce Tainio: Amending Soil Microbial Life, from the 2005 Eco-Ag Conference & Trade Show. (1 hour, 2 minutes) Listen in as the popular agronomist explains how to feed the microbial life in your soil, and develop optimal microbial biodiversity.

Those organisms living in the rhizosphere, primarily bacteria, not only make nutrients available to the plants — they also provide a protective layer against pests and diseases. It’s a win-win for the plants and the bacteria living in the rhizosphere.

It’s strange to think that plants have a hard time getting enough nutrients when soils are composed of around 45 percent minerals. Many of those minerals are the nutrients plants need to grow, photosynthesize, flower, pollinate and produce fruit or seeds. Although soil is a huge bank of minerals, most of those minerals are not in a form the plant can use.

Nitrogen, sulfur, phosphorus and many trace elements are all either dependent on soil life to make them plant-available, or they greatly benefit from microorganisms changing their form from one that’s hard to utilize to one that’s ideal for the plants.

An analogy I once heard at a farming conference in Australia is that microbes are the bridge between the soil minerals and the plant roots. I really like that analogy, but I would add to it that it’s an active bridge, one where transformations are taking place as things cross the bridge — like a highway bridge that takes semi-trucks full of minerals and converts them as they move across so they end up being small boxes of food at the other side, ready for plants to consume.

How the Microbial Bridge Works

The best example of the role of the microbe bridge in turning unavailable minerals into plant nutrients is how plants take up nitrogen. Just over 78 percent of the Earth’s atmosphere is nitrogen, but in its gaseous form nitrogen doesn’t do the plants much good. It’s like being thirsty while lost at sea. You may be surrounded by water, but you sure can’t drink it!

Plants are surrounded by atmospheric nitrogen, but only microbes are able to turn that nitrogen into a usable form. Microbes also provide nitrogen by transforming soil organic nitrogen (the nitrogen tied up in microbe bodies, mainly in the form of amino acids and proteins) and making it mineral nitrogen in forms of ammonium and nitrate that plants can take up. Without microbial nitrogen fixation and microbial breakdown of organic nitrogen into mineral nitrogen, there would be a great deal fewer plants on our planet. The microbes are the bridge that make the soil/plant system work.


Sulfur follows a similar process, but without the atmospheric fixation component. Most of the sulfur in the soil is organic sulfur, tied up in living and decomposing microbe bodies, and it takes microbes to change organic sulfur into plant-available sulfate.


Phosphorus is another mineral that greatly benefits from microbial transformations. Most farmers are aware of the important role of mycorrhizae in increasing the root surface area and accessing phosphorus that plants would otherwise have a difficult time accessing. It is less well known that up to 50 percent of the phosphorus in soil is organic phosphorus, tied up in living microbes and decomposing roots and microbes.

corn nitrogen comparison
The corn on the left was grown following a worked-down mature vetch crop, while the corn on the right was grown following a worked-down young clover crop. While both cover crops provided ample nitrogen credits, the mature vetch tied up nitrogen as it broke down because it was more lignified, and that nitrogen wasn’t available for the following corn crop. The young clover plants broke down quickly and rapidly released ample nitrogen to support the corn crop.

Organic phosphorus is mineralized to plant-available forms only through microbial activity. Phosphorus converts easily into unavailable forms in both acidic and alkaline soil conditions, so it is a huge advantage to have it in an organic form where it is relatively stable until microbes can mineralize it into a plant-available form.

Many other micronutrients benefit from the microbial bridge to make them plant-available. Microbes can change the form of a nutrient, change its charge, or hold it in a way that makes it less likely to tie up and easier for a plant to take up when it’s needed.

In addition to the role of the microbial bridge in changing the form of nutrients to make them plant-available, microbes are also a highway of nutrient movement and nutrient-holding capacity. While many nutrients require microbes to change their form, all plant nutrients benefit from microbes moving them around, concentrating them in the rhizosphere, and holding them in their bodies so they don’t tie up into forms that are mostly unavailable to plants.

On-Farm Intensive with Zimmer Ag

Learn about soil health in person with Gary Zimmer

The Acres U.S.A. On-Farm Intensive – starting in summer 2021 – is held in partnership with experienced farm consultants Gary Zimmer and Leilani Zimmer-Durand at their famous Otter Creek Farm near Lone Rock, Wisconsin. This two-day educational experience will help farmers, growers and land owners maximize their land’s potential. 

Learn more here!

Building Your Bridge

Knowing how important the microbe bridge is to plant growth and health is a great incentive for building a stronger bridge on your farm. There are a number of different practices that enhance the strength of the microbe bridge, and all involve feeding an abundance of soil biology year-round.

Biology is the key to building a strong microbe bridge, and diversity is what leads to abundant biology. You need diversity because the plants determine the soil life, and different types of plants both feed and benefit from different types of soil life. It’s just like choosing the right inoculant for your legumes — you wouldn’t use the same one on soybeans as you would on clover. The plants are specific to their microbes.

This is true not only for the microbes living around the roots in the rhizosphere, but also for those that digest plants in the soil. The stage of maturity when you feed the plant to the soil microbes is critical if you want to control nutrient availability and biology.

Young succulent plants have a different solubility, or as dairy people call it, “digestibility.” If you want to grow a crop like corn that requires a lot of soluble nutrients and extra nitrogen, you feed the soil microbes a highly digestible crop like young rye plants or alfalfa. Not only will these plants release nutrients quickly as they break down in the soil — they are also high in sugars that feed soil bacteria.

Soil bacteria consume easy-to-digest materials and have a 5:1 carbon-to-nitrogen ratio in their bodies. They live and die quickly and are consumed by other soil organisms like protozoa, which are closer to 10:1. The difference in the C:N ratio of the protozoa compared to the bacteria means there is a lot of extra nitrogen the protozoa don’t need for their own metabolism that gets excreted back into the soil as plant food. By feeding your soil bacteria you are also boosting nitrogen cycling and feeding your plants nitrogen.

If you allow your cover crop plants to get large, they will have more complex carbons and will be mostly fungal food. This gives a very slow release of nutrients and leaves behind more undigested, highly complex carbon. It’s good for building soil organic matter but not so good if you farm organically and need a lot of active nutrient cycling in your soils because you can’t buy commercial soluble fertilizers to make up for the nutrient tie-up as the lignified plant materials slowly break down.

Growing mixed plant species also results in a more heterogeneous group of microbes and digesters in the soil in which no one population can become dominant. This keeps things in check. The diversity of plant species also builds a stronger microbial bridge that provides a variety of minerals and plant compounds essential for plant health.

healthy soil life and cover crop
Healthy soil life with a newly incorporated mixed-species cover crop. This young cover crop will provide nutrients and carbon to feed the soil biology as it breaks down.

Microbial digestion is also affected by air. Burying residues deep may not be ideal for the type of organisms you want to have in your soil. That’s why I like to shallow incorporate my residues.

By shallow incorporating, some of the residues do still remain on the surface to protect the soil from runoff, but most of them are in the shallow aerobic zone of the soil where they can be broken down by beneficial microbes.

The bigger and denser the crop being worked in, the deeper it can be incorporated without harming soil structure or going down into the anaerobic zone where it won’t break down easily because there is much less microbial activity. Strict no-till with chemicals may be your methods of managing cover crops, but you do give up some benefits of microbial digestion if you don’t incorporate your cover crop. This is still better than not growing cover crops at all, but it’s like putting part of the feed you give your cow on the other side of the fence!

Your soils have a certain ability to dish out minerals, and the microbial bridge is key to making those minerals that are already in the soil available to plants. But that may not be enough. You need to apply fertilizer to feed your crop above and beyond your soil’s ability to provide minerals. That’s how to get high yields on lighter soils.

Be sure to add only quality, low-salt, balanced nutrients. By applying nutrients that are mixed with or bound to carbon, the fertilizer mirrors how things work in the soil. For liquids, molasses-based fertilizers provide sugars that not only buffer out the fertilizers but that provide readily available food for the soil biology to support the microbial bridge.

For dry granulated fertilizers, I like humates and fertilizers made with the digestate from anaerobic digesters on dairy farms. What comes out of the manure digester after the easy energy has been turned into methane is a mix of minerals, fiber and dead bodies of bacteria. We remove the fiber and add other minerals to make fertilizers. Not only are the nutrients in a carbon base, but they also have biological stimulants along with humic acids. This mirrors what happens in active, healthy biological soils to support microbial activity.

Being a biological farmer means switching focus from chemistry to feeding and taking care of soil biology. The emphasis is on the microbial bridge, rather than on soluble fertilizers, to get nutrients to plants. When the soil, plants and microbes are in balance, and a fertilizer that includes trace minerals is applied, you should not need to buy all the plant-protective compounds, technologies and chemistry that many farmers today depend on. Not only are those inputs expensive, but they won’t make your farm any better in the future. Build a strong microbial bridge, focusing on biology and soil health, and you will be well on the road to being a successful biological farmer.

By Leilani Zimmer Durand & Gary Zimmer. This article appeared in the December 2018 issue of Acres U.S.A. magazine.

Gary Zimmer and Leilani Zimmer-Durand are the authors of Advancing Biological Farming, a sequel to Gary’s earlier book, The Biological Farmer — both published by Acres U.S.A. Leilani has written extensively about biological farming and runs training courses for farmers and farming consultants on the principles of biological farming at Midwestern BioAg, where she serves as vice president of education initiatives.

Gary is an organic dairy farmer, an accomplished speaker, a sought-after farm consultant and president of Midwestern BioAg, a biological farming products and services company.

Gary and Leilani also previously presented at the 2018 Acres U.S.A. Conference & Trade Show in Louisville, Kentucky. To download audio and video of their presentations, visit Acres U.S.A.

Learn in the field with Gary Zimmer!

Spend 2 days this summer on Gary Zimmer’s Otter Creek Organic Farm in Lone Rock, Wisconsin. Learn how to use biological farming for better soil health and to improve your farming operation. July 19-20, 2021. Learn more here!

The Acres U.S.A. On-Farm Intensive is held in partnership with experienced farm consultants Gary Zimmer and Leilani Zimmer-Durand at their famous Otter Creek Farm near Lone Rock, Wisconsin. This two-day educational experience will help farmers, growers and land owners maximize their land’s potential. Learn more here!

Harness The Power of Earthworms

By Paul Reed Hepperly, Ph.D.

When moist, practically all soils from tundra to lowland tropics support the activity of earthworms. Largely unseen, earthworms are a diverse, powerful workforce with the capacity to transform soil into fertile ground.

Found in 27 families, more than 700 genera and greater than 7,000 species, earthworms vary from about 1 inch to 2 yards long. Their living mass outweighs all other animal life forms in global soils. Although we may view earthworms as being both prolific and productive, do we fully appreciate our human capability to favor their beneficial efforts as allies allowing farms and gardens to flourish? I think not.

Earthworms’ powerful activities include promoting favorable soil structure, increasing biological diversity, improving soil function, balancing nutrients needed by plants and animals and optimizing living soil.


In commercial vermicompost, earthworm production is favored by a brief compost cycle to produce earthworm diet. Because earthworms derive their nutrition from fungi, bacteria, protozoa and nematodes, their lives and those of teeming masses of microorganisms and microbes are closely interlinked. Trained as a plant pathologist, I marvel at the unseen microscopic realm and its power to transform. Scientists have found that microbes break down plant and animal debris. This process promotes the nutrition and health of earthworms, microbes, soil and everything that depends on the soil.

handful of worms
Earthworms not only play productive roles in sustainable agriculture, but they have enormous capacity to help mitigate our elevated atmospheric greenhouse gas content by reducing carbon and nitrogen gas.

As earthworms turn and churn, they function as effective premier plant residue shredders. Their work helps liberate plant nutrients into the digestive tract by microbe activity while the earthworms themselves are favored.

We are asked by some great thinkers to ponder on the earthworm and its significance. Charles Darwin referred to earthworms as “the intestines of the soil.” Rudolf Steiner, originator of biodynamic agriculture, referred to them as the “stomach of the earth.”

Earth Motor

Earthworms play a critical role in improving and enriching soil. Through their tunnel networks they create air channels, optimizing aeration and providing conduits for watering the soil. By allowing water and air to channel through the soil they promote rooting. Roots and plant residue feed the rich microflora that feeds the worms. Worms feed the earth that nourishes the plants. This is a productive interdependent life cycle. The ability to maximize water percolation also minimizes runoff, and reduced runoff greatly reduces soil erosion.

earthworm anatomy
Earthworm Anatomy: Diagram shows the position and morphology of the calcium glands of the earthworm.

Together earthworms and microbes are the great digestive fermenters. They join together in shared shredding/digesting. As digestion results from joint effort, insoluble plant materials are solubilized. In the alimentary tract, what was waste is consolidated into value-added packets known as castings.

Earthworm castings are an ideal organic amendment/fertilizer with greatly increased nutrient solubility compared to the organic materials they originated from. Castings are particularly rich in phosphorus which stimulates seedling and root growth and extension.

Unlike most synthetic fertilizers, they are well balanced in macronutrients, secondary and micronutrients. The humic substances in earthworm castings support the foundational physiological processes of plants such as photosynthesis and respiration. Their growth regulation properties include the ability to stimulate defensive reactions in plants, allowing them to deal with stress and adapt to difficult conditions.

Scientists have compared the earthworm tunnel system to a motor with pistons — the muscular earthworms are the piston drivers of the soil pump. Plant materials fuel the living soil machine with microbial-aided decomposition working together with the worms deriving their energy through the plant remains.

The earthworms drive plant material into the ground, infusing life into the whole system.

No Everyday Compost

micronutrient composition

In a strict sense, worm castings are not vermicompost at all. They are really earthworm manure. Unlike many other animal manures, however, casting are not laden with toxic ammonia. Earthworm castings are rich in organic nitrogen. This critical difference gives unique advantages over other animal manures. Earthworm castings are also distinctive in being rich in carbon and calcium.

Calcium, carbon and nitrate constitute a trifecta. They avoid the ammonia toxicity and salt issues common in ammonia-rich manures and fertilizers. Because of the organic nature and low ammonia, earthworm castings can be used in close proximity to seedlings without plant toxicity.

Besides calcium, red earthworm castings are exceedingly rich in iron. Copious calcium excretion is critical to the metabolism and digestion of earthworms, and earthworms can be greatly restricted in acid soils. Where soils are high in alkalinity, the ability of plants which originally adapted to more acid environments, show inability to absorb and utilize iron. This results in plants yellowing due to iron deficiency or chlorosis. The organic, chelated form of iron from castings is ideal for such situations because they are readily soluble and rich in iron.

Humic materials from the earthworm microbial combo are champion chelators. Earthworm castings have a 6.9 pH, neither highly acid nor alkaline. This neutral, slightly acid pH is friendly to both earthworms and most plants they depend upon.

Besides the castings, the earthworm ejects granules akin to miniature lime stones. The fine structure of earthworm granules is both beautiful and well organized. Like castings these granule outputs are dispersed into the soil, where they act to benefit soil fertility, biology and structure.

In its composition, the earthworm granule is mostly mineral. Although calcium is its biggest component it usually features a silica center clear in electron micrographic analysis. The granule is a rich source of a diverse variety of micronutrients. Under the scanning microscope, these little gems resemble mineral snowflakes.

An abundant earthworm population will produce about a ton of these per acre every year under good conditions. As such, the earthworm-tilled soil becomes limed with calcium carbonate quartz granules besides being enriched with a critical spectrum of major, secondary and micronutrients.

These granules take carbon dioxide that was in our atmosphere as greenhouse gas and trap it as insoluble carbonate. The little lime stones neutralize the soil, preventing it from becoming overly acidic. Calcium also serves as a mortar for cementing soil aggregates together, conserving both carbon and soil structure.

Earthworms On the Farm

In upstate New York, longtime organic farmers Klaas and Mary Howell Martens were asked to review my work on worms. Upon reviewing this article, they urged me to go beyond the living soil machine metaphor.

They asked me to stress the cycling and mineralization capacity of earthworms. On their farm, in their personal witness, they testify to cover crops of over 3 tons of fall dry matter residue being cleaned up by early spring by the worms. They were amazed when they analyzed the soil that same spring. The soil analysis showed 360 pounds of N, 40 pounds of phosphate and 160 pounds of potash per acre available, more than sufficient for an optimum maize crop. This was without any application of synthetic chemical fertilizer.

Relying on the legumes and worms to till and feed, Klaas reported, “Earthworm recycling and mineralization occurs sometimes overnight. I have seen large clumps of leaves fall from my spreader in the spring and days later I went back and nothing was there. Yet, upon looking closer at the soil surface it was covered with worm castings … amazing.”

A Deadly Trio

In conventionally farmed and tilled fields it is common to find few or no active earthworms. Toxicity of pesticides commonly used in the field crops, the destruction of their habitat by excessive tilling, and acidity and toxicity of fertilizers constitute a deadly trinity for earthworms. When appropriate worm environment is produced all of these constraints are eliminated and the need for synthetic fertilizer is reduced or eliminated.

Soil acidity is the mortal enemy of earthworms, and the use of ammoniated fertilizers and tillage can largely stymie their beneficial natural soil-building potential. Earthworms are well known as premier bio-indicator organisms, revealing soil potential and overall environmental health.

In a mechanized agriculture vast mines of calcium carbonate rock are crushed into fine powders and transported to depots and then to farms where massive spreader trucks lime the fields.

Can we be more thoughtful in promoting natural earthworm populations? Yes, let us begin as farmers and gardeners by identifying acidic, low calcium soils and spread lime to remediate this common condition. Let us also incorporate manure, compost, cover crops, rotation and other sustainable practices.

Synthetic nitrogen fertilizer is directly toxic due to ammonia content and indirectly by its effect on acidifying the soil. When fertility is largely based on ammonia, the absorption of the ammonium ion causes the plant to release hydrogen ions to maintain electro-neutrality. This causes an acid release that first invades the root zone and continues to expand into the soil profile itself.

Earthworms promote a natural liming and are favored by liming. Calcium, I believe, is used by the earthworm to lime the soil as they themselves are sensitive to heavy metals, such as aluminum, which abound in soil. When these are soluble as in an acid environment, they are deadly, but when acidity is buffered they are harmless.

The only nutrients available to plants are those that become soluble. Carbon is the primary element in earthworm castings. This high carbon content demonstrates the organic nature of this amendment and organic nature is key for solubility of difficult-to-dissolve minerals. Tests show copper, manganese and zinc have water solubility of 15 percent or less without humic substances. On the other hand, when using organic chelation with soluble organic material, water solubility increases to over 85 percent, more than five times solubility in water alone. Fulvic and humic acids are champion organic chelators.

Carbon & Calcium

Professor Albrecht was a well-known proponent of the role of calcium. He envisioned calcium as the key to unlocking soil fertility. After carbon, calcium is second in abundance in earthworm castings. Unlike synthetic amendments that do not address secondary nutrients, earthworm castings do just that. Castings have abundant nutrients in balanced rations.

Calcium provides a key not only to structure and nutritional aspects for the plant but also acts as mortar in the formation of soil structure or aggregation. It helps granulate or aggregate the particles and stabilizes them from erosive force by its cementing action, which helps water and nutrients flow through the soil system. When earthworms build their soil profiles, they need mortar to be master builders.

Since the 1980s more and more research has shown calcium has some amazing capabilities. In humans, calcium is involved in the structure and function of our bones. As calcium granulates and coagulates soil aggregates, the serum calcium is critical in this defensive blood clotting in animals and humans. As calcium is lost in membranes the defensive reactions of plants are triggered. When calcium is low in plant cell walls and membranes, they become very susceptible to soft rot by fungi and bacteria.

Too Good to Cast Off

composition of earth worm

Turned, high-temperature compost is well documented as an excellent organic input. Yet, the value of earthworm castings is less recognized and cooler in temperature and impact. In this respect, castings not only have excellent value, but exceed those present in turned hot compost — in the total and range of macronutrients, secondary and micronutrients, they beat the turned hot compost hands down.

Hot composts can pasteurize the substrate yet the beneficial microbes need a cooler ambient temperature, which is found in the earthworm environment. In the story of Old John Henry, the mythic miner challenged the mining machine and died trying to defeat it. Our subterranean earthworm hero “John Henry Earthworm” meets the challenge of tilling soil and liming it. However, he is not beaten by the machine. In fact, the biological force of earthworms can prevail over the machine in this contest when the emphasis is on the potential of that force and they stay healthy and alive.

Global Opportunities

Many of us in the center parts of North America are spoiled by being blessed with wonderful, comparatively young prairie soils founded on limestone parent materials. These soils may have fewer concerns about acid soil infertility compared to the vast majority of tropical soils in the developing nations. This tropical problem can be found in rich red clay soils in the southeast United States.

biomass of biological components

Few peoples in Central and South America, Africa and tropical Southeast Asia are so well blessed as we, the people from the North American maize and soybean belt.

Tropical areas are notably plagued by possessing the majority of soils which are old, degraded and suffer from acidity, toxicity and deficiencies.

Consider that even commercial North American farmers using synthetic fertilizer typically add up to 1 ton of lime each corn crop to neutralize their heavy ammonia dependence and use. There is much untapped value in earthworms and they make sense in a wide range of areas, both tropical and temperate. An agriculture which will flourish for millennia will need to take earthworms into account not only as the prime soil health bio-indicators but also as the master engineer and builders of the soil machine.

Certain areas in the eastern half of the United States, tropical South America, Africa and Southeast Asia are dominated by acid, infertile soils.

The use of synthetic ammoniated fertilizers will worsen this all-too-common condition. Fortunately, nutrients from earthworms are ideal based on nitrate nitrogen form and its liming effect based on calcium in the worms’ metabolism. In addition, in countries throughout the world there is no shortage of limestone for agricultural use.

Many organic farmers have noticed slow initial nutrient release response from organic amendment. This can constrain high yields because of the low solubility of nitrogen and other critical nutrients. This is avoided with the earthworm castings, which are rich in soluble nitrogen as nitrate and soluble phosphorus for pop-up growth needs. They have

available humates from soil organic matter and complete secondary and micronutrients to overcome an array of issues. The best point is that their nitrogen as nitrate does not acidify the soil as common ammoniated synthetic nitrogen does.

While synthetic fertilizers are classified based on nitrogen, phosphate potassium salt contents alone, this reliance can easily lead to nutritional gaps in the supplies of essential secondary and micronutrients which are not considered. More importantly their use and dependence does not avoid soil acidity issues over the long term but rather will generate them.

In contrast, the worm castings provide a full complement of essential micronutrients playing critical roles in plant health and the secondary nutrients essential to plants and animals.

Because these are needed in relatively small quantities, and organic products have better solubility and retention characteristics, these can be utilized efficiently and economically with better environmental and energetic footprints. When the best natural production systems are used, earthworms are favored and do not need continual application and reapplication.

While the earthworm casting has significant nitrogen, it is in nitrate rather than ammonium form. Nitrate, when absorbed by plants, causes release of hydroxyl ions, working together with the calcium carbonate granules to lime the soil, not to acidify it. One negative nitrate in the plant, leads to one negative hydroxyl out of the plant. This conservation of charges results in liming the root zone or rhizosphere. This in turn helps the rhizosphere and earthworm to create favorable environments for the plants and themselves in the virtuous cycle. This working together is especially important for the problematic, acid, infertile soils in the majority of struggling areas in the global tropics.

Our tropical agricultural resource is our ace in the hole in globally regenerating the world environment and reversing greenhouse gas issues.

Research shows not only can worm castings stimulate yields over that of an optimum rate of synthetic fertilizer inputs but indeed exceed them substantially. This is related to not having the high salt index of synthetic fertilizer and being a complete nutrition. We have shown that castings have primary, secondary and micronutrients at ideal levels. Humic materials, that are produced by the microbial and worm tag team, are able to stimulate plants as growth regulators at parts per million dosages.

Finally, the rich microbial population has been associated with pathogenic fungi and bacteria suppression. In addition they possess the ability to stimulate the signal active defensive actions of plants to insect pests and adverse environmental conditions.

After seven years working with worms, I have come to the conclusion that my earth-changing ability is exceedingly small compared to my underground friends, the earthworms. For this reason I ask us to transform our intention in regards to the unseen and unheralded worm that works tirelessly and constantly for our benefit and that of the environment. Give them a chance and they will reward you with their endless, tireless efforts.

This article appeared in the June 2015 issue of Acres U.S.A.

Paul Reed Hepperly, Ph.D., scientist, consultant, educator and advisor, previously served as the research director for Rodale Institute, 2002-2009. His son Reed Paul Hepperly is CEO of Hepperly Enterprises, a premium compost supplier and developer of tropical root crops in Mayaguez, Puerto Rico. Paul resides in Tennessee.

How to Establish Dung Beetles in Pastures

By Spencer Smith

I only recently became interested in dung beetles, largely because it has only been recently that we have had any to become interested in. As a rancher, I must create the conditions for dung beetles to thrive, and they will come.

The first time I saw dung beetles completely bury a manure pat in a number of hours, I was hooked. I wanted to learn all about them: what they do, how to help them establish in pastures, how they work, etc. My continued observations and research has led our family to develop a deep appreciation of these hard-working creatures. So much so that we created our updated business logo in honor of them.

Our daughter art directed the logo and our neighbor, Brian Taylor, created it. We get a lot of stares when people see our logo on the side of our truck, but we hope it piques their curiosity enough to learn more about dung beetles and the vital role they can play on a healthy farm or ranch.

Mark Sturges, Meet the Beetles, from the 2007 Eco-Ag Conference & Trade Show. (51 minutes, 28 seconds.) Listen in as Mark Sturges, professional grower and input provider, talk about how and why beetles can help you grow your crops.

Dung beetles in pastures is a sign of a healthy and productive land base. However, to the alarm of entomologists and ranchers worldwide there has been a decline in the population of dung beetles on industrially farmed land.

Recent studies of nature’s “pooper scoopers” have indicated that these amazing creatures are important to the health of the soil and to the farmer and rancher’s bottom line.

Types of Dung Beetles

There are three main types of dung beetle, identified by brooding or nesting behavior. The three types include: tunnelers (paracoprids), dwellers (endocoprids) and rollers (telecoprids).


The tunnelers are the most common vartiety on our ranch in Northern California. These amazing workers zip around looking for manure and dive right in. Once the dung beetle finds a fresh pat of manure it begins to eat and tunnel underneath the manure pat. It does this so that it can move the fresh, tiniest pieces of manure down into the soil, where it lays its eggs. The eggs then hatch into larvae that eat the buried manure until they metamorphize into adult beetles.


The dwellers find their ideal homes and set up residence there. These beetles occupy a manure pat, consume massive amounts of manure and lay their eggs in the aboveground manure pat. Some varieties of these dwellers’ larvae are known to eat fly eggs and larvae as well. Establishing a healthy population of dwellers on your farm or ranch will help deter the presence of horn and heel flies, which are livestock pests.


The rollers are the most famous of all the dung beetle varieties with much fanfare surrounding how they work and how they use the stars to locate their home using celestial cues. This type of dung beetle only makes up about 10 percent of all dung beetles, but they do amazing work. Scientists and farmers alike have noticed for decades that when there are dung beetles present there is a dramatic decrease in the fly population.

Fly Control

A recent article in Progressive Rancher reveals that the cost of flies to U.S. producers is more than $1.5 billion. Given this staggering cost of managing the impact of flies on livestock, dung beetles could really help producers who are losing livestock production to horn, heel and face flies.

Will Winter: Pasture, the Profit Maker, from the 2006 Eco-Ag Conference and Trade Show (53 minutes, 51 seconds). Listen in as professional livestock consultant Will Winter discusses ways to manage pasture profitably.

Dung beetles affect the flies in a variety of ways. Dung beetles that roll their prized possessions, or “brood balls,” excrete a chemical on the ball of dung that will repel flies from trying to lay their own eggs on the piece of dung. Other varieties of the dweller beetle larva will prey on the larvae of the flies.

I think the main impact of dung beetles is the fact that they can consume and bury massive amounts of manure each day. In fact, it is estimated that a single dung beetle will bury 250 times its own weight in dung per day. Dung beetles move flies’ eggs and brooding sites below the soil, thus breaking the life cycle of the flies. Livestock producers in the United States could collectively save more than $1 billion, simply by putting dung beetles to work.

Improved Pasture Fertility

The next essential point in the conversation on these amazing creatures is their impact on pasture fertility. If you have ever taken the time to analyze the manure in your pastures you may notice a couple of different things, if you have dung beetles. The first thing you may see is that the manure in question looks like Swiss cheese, there are no big pieces of dry manure left, but only the high-fiber chaff that is broken into many small pieces.

What is happening here? The answer is quite impactful to pasture health. Dung beetles search for the best, most nutritious manure in the pile. This is what they ball up and roll away, or bury directly under the manure pat.

The manure that falls from behind your cattle (or other livestock) typically has a carbon to nitrogen ratio of about 24:1. The dung beetle’s ideal diet, and best material for their brooding sites, is around 5 or 7:1 carbon to nitrogen. The implications of this are significant because dung beetles search out and bury the highest nitrogen portions of the dung and move that manure to the rhizosphere (root zone) in the soil. This means less nitrogen is leaching back into the atmosphere. Furthermore, the beetle larvae only consume about 40 to 50 percent of the buried nitrogen-filled dung, leaving the rest to feed the roots of the plants in the pasture.

Soil Aeration & Water Management

What is the effect of dung beetles on the water cycle in fields? We refer to the dung beetles on our ranch in Northern California as the hardest workers on our team. Not only are they working non-stop to add fertility and break fly and parasite cycles, they are also tunneling loads of holes into the rhizosphere (root zone of the soil). This tunneling aerates the soil, which increases how quickly water can infiltrate the soil. A healthy water cycle means healthier plants and more photosynthesis, which means more feed for livestock.

One of the biggest issues facing agriculture today is water. Water-related issues dominate the news (at least in California): chemical runoff from farms, droughts, floods. Luckily for farmers and ranchers everywhere, the mighty dung beetles can help out (for free!), when it comes to dealing with symptoms of a broken water cycle.

As farmers, our primary objective must be to ensure effective rainfall and irrigation management. Whether we live in the foothills of California where it is common to get up to 60 inches of rain per year, or if we live in the Great Basin and only receive 6 inches, farmers typically have the same complaints. Either it is too dry or too wet, oftentimes this happens in the same year!

Flood and drought cycles are a part of business for farmers everywhere. We must get better at dealing with them if we are going to stay competitive in the face of future erratic weather patterns, spurred on by climate change.

Effective water cycle refers to not how much rain or irrigation is added to a given acre, but how much of that water will actually enter the soil for plant use. Dung beetles are keenly equipped to assist in improving our water cycle as the brooding burrows that they create, either under the dung pat or rolled to the root zone, improve water infiltration. Not only can the water infiltrate better, but as it mixes with residual manure left over from the larvae, the water will lock into the rhizosphere like a sponge. This gives plants perfect access to water right where they need it most — at their roots.

With this aeration, the soil can clean the water and improve water quality for downstream users. Healthy soil means clean water, and a big part of healthy soil is a robust dung beetle population.

Managing for Dung Beetles

Our family’s ranch, Springs Ranch, became certified organic about seven years ago. With this transition to becoming certified, we no longer dewormed our own cattle or any of the pasture cattle we graze on the ranch.

After a few years of being certified organic, we noticed that we did not have the fly or parasite issues in our livestock that we once did.

After careful observation of many piles of poop, we observed that the dung piles where decomposing quite quickly. We noticed that we had some dung beetles moving in to assist in our pasture cleanup. Over the last few years our population has increased dramatically. We are at a point now that a dung pile can be completely dismantled in as little as a couple of hours.

dung beetles in field
A pair of beetles roll away a squirrel pellet at Springs Ranch in Fort Bidwell, California.

If you are interested in these amazing critters moving into your fields all you have to do is stop killing them with livestock wormers.

It has been shown that if you worm your livestock you will negatively impact dung beetle populations for up to a month. This is a function of some residue of the medication in the manure where the dung beetles lay their eggs. As the eggs hatch and the larvae eat the poisoned manure, the larvae are killed and never make it to adulthood. Thus, they are not around to do the job you need them to do.

This does not mean that you have to stop worming your livestock altogether if you want to increase beetle populations. Dung beetles become active in the late spring and hot summer. If you are in a situation where you need to worm your livestock, research the beetle life cycle in your environment, and then worm your cattle when the beetles are dormant. For us in California, this would be in the late fall or winter.

Recent research examines which grazing techniques are best for luring dung beetles into your pastures. It turns out that utilizing a higher stock density, short duration grazing strategy works best.

This leaves ample food for the beetles in a relatively small area; making food, as well as members of the opposite sex, easy to find. This means that food and reproduction opportunity are abundant, and thus the conditions are right for significant population growth.

Financial Impact

With face, horn and heel flies costing ranchers between $30 and $50 dollars per head of cattle, the impact of parasites on livestock is clearly significant. In a paper by Adam Byk and Jacek Pietka, “Dung Beetles and Their Role in the Nature,” it was discovered that dung beetles have the potential to reduce fly populations by 95 percent.

Dung beetles reduce flies and parasites, increase fertility in pastures and allow for more effective water cycling. Managing for these hard little workers is a no-brainer (at least for our family).

Ask yourself: What would your farm financials look like if you could increase production through better fertility and water management with less pressure from flies and parasites?

I believe every farmer is seeking increased soil fertility, effective use of rainfall and fewer parasites. This is true wealth! Dung beetles will do the work to create this for you. The job of the farmer or rancher is simply to create the conditions for dung beetles to thrive

About Spencer Smith

Spencer Smith is a Savory Field Professional and a huge fan of dung beetles. Savory Global Network hubs provide accredited Holistic Management and regenerative agriculture training and support across the world. Abbey and Spencer Smith manage the Jefferson Center for Holistic Management, the Savory Global Network hub serving Northern California and Nevada. Learn more and contact the Smiths with your grazing and dung beetle-related questions. This article appeared in the November 2018 issue of Acres U.S.A.magazine.