Leisha I am finishing Plant & Kitchen Alchemy, a book that has grown to more than 550 pages of personal experience, practical knowledge and over 80 kitchen alchemy recipes centered on food as medicine. As I moved through the final edits, I realized I had spent a great deal of time showing how closely the soil microbiome and the human microbiome are connected, how fascinating that relationship is and how much it changes the way we think about food, plants and health.
What I had not really entered was the danger sitting inside that same connection. We are damaging microbial life in the soil through chemical inputs, disturbance, contamination and loss of biological diversity, while the human microbiome is being exposed to another enormous load through food, water, plastics, pharmaceuticals and industrial compounds. Once you understand how directly soil, plants, food and our own microbial ecosystems are linked, it becomes impossible to treat these as separate problems.
So an appendix chapter showed up. I am sharing part of it here because I care deeply about this subject, and because it reaches far beyond agriculture. This is not only about the soil beneath our feet. It is about the food grown in that soil, the microbes living inside us, and ultimately, it is about us.
Everything around us is chemistry. The red of a tomato is chemistry, as is the fragrance released when rosemary is crushed. Vinegar, lactic acid, minerals, humus, root exudates, plant pigments, enzymes, amino acids and the compounds produced by our intestinal microbes all belong to the chemical world. Every root, cell, ferment, meal and breath depends upon molecules being joined, separated, exchanged and transformed.
So, when we talk about chemicals in agriculture, food and health, I do not find it useful to divide the world into natural things on one side and chemicals on the other. Water, oxygen, magnesium and curcumin are all chemicals. What matters is which molecule is present, how much of it is there, where it came from, how persistent it is, what it interacts with and which living community has to deal with it.
Human activity has introduced an enormous range of compounds into soil, water, food and our bodies. Some disappear relatively quickly, while others remain for years or decades. They may bind tightly to soil, travel with water, enter plants, be transformed by microorganisms or accumulate in living tissues. Some change chemical form several times along the journey, which means the disappearance of the original molecule does not necessarily mean the story is finished.
Follow this path far enough and something important becomes very clear. Soil, plants, food and the human body are not separate systems. Agricultural residues, industrial compounds, plastics, metals, pharmaceutical residues and chemicals carried through water and organic materials can move through the same cycle that carries minerals, carbon, plants, microbes and food.
We are putting tremendous pressure on the biological communities supporting that cycle, while much of modern agriculture still treats soil as though it were little more than a medium capable of receiving whatever we put onto it. Soil is habitat. Its bacteria, fungi, protozoa, nematodes and other organisms participate in nutrient cycling, soil structure, decomposition, plant relationships and the movement of minerals through the food web.
The same story continues inside us. Our digestive tract is another densely populated microbial ecosystem receiving whatever comes through food and water. We are learning how important this community is at the same time that we are exposing it to mixtures of modern compounds far more complicated than anything a laboratory can easily reproduce.
The soil microbiome and the human microbiome may appear to live in entirely different worlds, yet food connects them. Change the microbial community in the soil and we change the conditions in which plants grow. What those plants carry eventually reaches another microbial community inside us, while part of what leaves humans and animals can return through wastewater, manure, compost and land application.
Once we follow that cycle, environmental health, soil health and human health become part of the same conversation. It is all connected.
Soil Receives What We Give It
Agricultural soil receives far more than seeds, rain and compost. Depending upon where it is and how it is managed, soil can receive agricultural chemicals, fertilizers, manure, irrigation water, plastic fragments, atmospheric particles, road dust, industrial residues and substances carried through animal feed. Land close to mines, factories, busy roads, contaminated waterways or old dumping sites can carry another chemical history entirely.
A large European study published in 2026 gives us an uncomfortable idea of how widespread agricultural residues have become. Researchers examined soils from 373 sites across 26 countries and looked for 63 pesticide compounds while also studying bacteria, fungi, archaea, protists, nematodes, arthropods and microbial functions. Residues were found in 70 percent of the soils tested and were associated with changes in biodiversity and biological functions involved in nitrogen and phosphorus cycling.
That matters far beyond the question of whether an individual chemical happens to fall above or below a legal limit. Bacteria, fungi, protozoa and nematodes are carrying out work plants depend upon, and disturbances to those communities can affect decomposition, mineral cycling, aggregation, carbon movement and what happens immediately around plant roots.
The molecule entering a field is also entering an ecosystem. Moisture, oxygen, food, minerals, organic matter, temperature, roots and thousands of neighbouring organisms influence what happens next. Soil pH, meaning how acidic or alkaline the environment is, can change both the chemical form and mobility of certain compounds.
One substance may bind strongly to organic matter and remain relatively fixed, while another travels through soil water. Rain can carry a mobile compound downward, roots can change the chemistry surrounding themselves and microbial enzymes can transform a molecule into something quite different from what was originally applied.
Soil is alive through all of this. Anything entering it becomes part of a biological and chemical environment already carrying an enormous number of relationships.
Microbes Meet the Molecule
Microorganisms possess an extraordinary range of enzymes and spend their lives dismantling, transforming and rebuilding compounds. This gives microbial communities an important role when unfamiliar organic molecules enter soil.
Some microorganisms can use portions of particular contaminants as sources of carbon, nitrogen, phosphorus or energy. Others modify a molecule while carrying out another metabolic process entirely. One species may complete the first stage of transformation and leave behind a compound another organism can use, creating chains that depend upon several members of the community.
Polluted soils can gradually select for organisms capable of tolerating or transforming what is present. Some populations increase, others decline and the microbial community begins reorganizing around the chemical conditions it is experiencing. The rhizosphere, the biologically active region immediately surrounding a living root, becomes particularly interesting because the plant continually releases carbon-rich compounds into this area and supports dense microbial communities.
Microbial transformation is fascinating, but a disappearing molecule has not necessarily become harmless. The original compound may be changed into a metabolite, a new chemical produced during biological transformation, and that metabolite can have different properties from the substance we began with.
Glyphosate gives us a useful example. One of its principal transformation products is aminomethylphosphonic acid, generally shortened to AMPA. Looking only for glyphosate can therefore miss part of what has happened because we also need to know how much AMPA remains, whether it continues to be transformed and how it behaves in the environment.
There has even been research using the microbial community from fermented sauerkraut in agricultural soil. In one field study, researchers applied raw sauerkraut fermentation liquid to soil while investigating glyphosate and AMPA residues. The work is interesting because it shows just how far microbial transformation can travel: cabbage grows in soil, microorganisms transform that cabbage during fermentation, and those microbial communities can then be returned to soil where another stage of transformation becomes possible.
That does not mean we should start pouring fermentation brine over every contaminated field and assume the problem has been solved. It demonstrates something much more useful: microbial communities have biochemical abilities we are still discovering, and diverse communities may accomplish transformations that a single organism cannot.
A bacterium may possess only one enzyme needed in a complicated pathway. Another bacterium may provide the next piece, fungi may participate elsewhere and compounds released by one organism can become food for another.
Healthy soil structure provides the habitat in which this can happen. Aggregates create tiny environments with different amounts of oxygen and moisture, roots continually release carbon and fungal strands move through the spaces between soil particles. When these habitats disappear, we lose part of the biological capacity of the soil along with them.
We cannot keep increasing the chemical burden and assume microorganisms will endlessly clean up after us. Repeated exposures can damage or reorganize the very microbial communities we are depending upon to perform this work.
What Are We Doing to the Soil Microbiome?
I think we need to be much more willing to talk about what we are doing to the microbial world beneath our feet. Across enormous areas of agricultural land, soil organisms are dealing with repeated disturbance alongside chemical residues, compaction, erosion, bare soil, loss of organic matter, concentrated nutrient inputs, reduced plant diversity and broken fungal networks.
The difficult part is that microbial decline does not necessarily announce itself in an obvious way. We usually notice soil deterioration once crops struggle, water stops infiltrating properly or erosion becomes visible. Bacterial, fungal, protozoan and nematode communities can be changing for years before anyone standing in the field notices what is being lost.
A crop can remain green while the biological system underneath becomes progressively more dependent upon outside inputs. Soluble nutrients can compensate when biological nutrient cycling weakens, while additional irrigation may temporarily compensate for declining soil structure and water-holding ability. The crop continues growing, so the system appears successful even as more of its biological work has to be replaced from above.
That is a strange measure of health.
If the plant survives only because we continually replace functions once carried out by a living community, perhaps we should be asking what happened to the community.
Soil microbiomes can recover remarkably well when habitat returns. Living roots, organic matter, plant diversity, moisture, protected soil structure and time give organisms something with which to rebuild. Continually applying the same pressures while expecting biology to recover beneath them makes very little sense.
The soil beneath our food is not simply the place where agriculture happens. Its microbial community is part of what makes agriculture possible.
Persistence Changes Everything
Some compounds are transformed relatively quickly, while others resist breakdown because their molecular structures are exceptionally stable. Per- and polyfluoroalkyl substances, usually called PFAS, provide a particularly troubling example.
PFAS are a large family of manufactured fluorinated compounds used in many products because they resist heat, water, oils and stains. Their strong carbon-fluorine bonds helped make them commercially useful and also make many members of this chemical family extraordinarily persistent in the environment.
Agricultural land can receive PFAS through contaminated water, atmospheric deposition and recycled organic materials. Their behaviour then depends upon which particular PFAS compound is present, the properties of the soil, the crop growing there and the environmental conditions.
Shorter-chain PFAS can behave differently from longer-chain forms. Roots, leaves, grains and fruits can also accumulate them differently, which means saying “PFAS is present in this soil” tells us only part of what we need to know.
Persistence also turns soil into a kind of archive. Decisions made decades ago can continue influencing living systems long after the activity producing the contamination has stopped, leaving future growers to inherit a chemical history they had no part in creating.
The Plant Is Not a Straw
Plant roots do not simply drink everything dissolved in the soil around them. They are living tissues containing membranes, barriers, transport systems and chemical gradients that influence what enters the plant and where it goes afterward.
A molecule approaching a root carries its own physical and chemical characteristics. Its size, electrical charge, solubility and affinity for water, fats or proteins influence whether it remains in the soil, binds to the root surface, enters root tissue or travels farther through the plant.
Plants can also transform compounds after uptake. Enzymes may change the molecule, attach additional chemical groups or move it into cellular compartments where it causes less interference with normal plant metabolism.
Some compounds remain primarily in roots, while others move through stems and into leaves, seeds or fruit. Two crops growing in the same soil can therefore contain very different amounts of the same contaminant, and even two parts of the same plant can tell different stories.
Research using reclaimed irrigation water has shown this variability with PFAS, pharmaceutical residues, personal-care compounds and chemicals associated with tire wear. The amount taken up can change according to the chemical, crop and irrigation conditions, and some compounds have even been detected in tomato fruit.
The plant is participating in this chemistry, and so are the microbes living around its roots.
Metals Stay in the Story
Metals need to be understood differently because ordinary biological processes cannot make an element stop existing. Lead remains lead, cadmium remains cadmium and arsenic remains arsenic, though arsenic is technically classified as a metalloid because it has properties of both metals and non-metals.
Microbes can alter the chemical form of these elements, organic matter can bind them and plants can move them between tissues. None of these processes removes the element from existence, so something appearing to leave one part of the system may simply have moved somewhere else.
Some metals, including iron, zinc, copper and manganese, are essential nutrients at appropriate concentrations. Excessive concentrations can interfere with living processes, while other elements have no known nutritional requirement and become particularly important when they accumulate in soil or food.
Their presence is not always the result of pollution. Rocks naturally contribute elements as they weather into soil, while mining, traffic, contaminated water, industry and waste can raise those concentrations significantly.
Laboratory testing becomes particularly valuable here. Soil may smell wonderful, crumble beautifully and contain a thriving microbial food web while still holding an unwanted concentration of lead inherited from something that happened decades ago. My microscope cannot tell me that, and biological observation cannot replace every kind of chemical measurement.
Plastic Has Entered the Soil Food Web
Plastic has become so ordinary in agriculture that we can almost stop seeing it. Irrigation lines, mulch films, greenhouse covers, seedling trays, containers, packaging, netting and storage materials all have practical uses, yet sunlight, heat, friction and weather slowly damage them.
The material does not vanish when it breaks apart. It becomes smaller, and particles below about five millimetres are generally described as microplastics.
Microplastics are now being detected in agricultural soils in many parts of the world. They can come from degrading agricultural plastics, compost, wastewater, sewage-derived materials, atmospheric deposition and other sources.
Plastic behaves very differently from a dead leaf or piece of wood. Microbes are adapted to work with natural compounds such as sugars, cellulose and lignin, while synthetic polymers can be far more difficult to dismantle. Certain microorganisms can slowly transform some plastics, but the ability varies considerably according to the polymer and environmental conditions.
Microbes also colonize plastic surfaces. Researchers call the community that develops on those surfaces the plastisphere, and the discarded fragment becomes a little microbial habitat inside the soil. Its surface can also collect metals and organic compounds from the surrounding environment.
We are introducing artificial islands into natural soil architecture and watching microbial communities reorganize around them.
Very small plastic particles raise further questions because researchers have detected some within plant tissues. We still have much to learn about how frequently this occurs under ordinary agricultural conditions and what it means once those plants become food, yet I do not need every question answered before deciding that continuously fragmenting plastic into agricultural soil is something we should avoid wherever we reasonably can.
Circular Systems Can Return Problems to the Soil
I love biological cycles. Kitchen scraps become compost, manure becomes fertility, plants feed microbes and carbon returns to the soil. Materials we once called waste become part of another living process.
Closing a cycle also means paying attention to everything travelling around it.
Manure carries part of the history of the animal that produced it, including feed, water, medications, bedding and environment. Compost carries the history of its ingredients, while reclaimed water carries whatever entered that water before treatment.
Materials derived from wastewater can contain useful nutrients and organic matter while also carrying PFAS, microplastics, pharmaceutical residues and other persistent compounds. Returning organic material to soil may still be valuable, but circularity alone does not guarantee that the material is clean.
I want to know where manure came from and what the animals were eating. I want some idea of what went into compost and whether plastic-coated materials, sewage-derived products or unknown waste were included. Irrigation water deserves the same attention because a small recurring input, repeated over many years, can eventually become part of the chemical history of a field.
A healthy cycle needs clean ingredients as far as we can reasonably achieve them. Otherwise we may become very efficient at cycling contaminants along with the nutrients.
Pharmaceuticals Do Not Always Stop With the Patient
A medicine does not necessarily finish its journey inside the human or animal who takes it. Some drugs are extensively transformed inside the body, while others leave partly unchanged or as metabolites that may retain biological activity.
These residues can move into sewage systems, manure and wastewater before eventually reaching soil or irrigation water. Researchers have studied pharmaceutical uptake across many crops and have found considerable variation according to the drug, the plant and the surrounding soil or water.
That does not mean every carrot grown with manure contains an important pharmaceutical concentration. It does tell us that the pathway exists and that molecules can move from medicine into waste, from waste into soil and water, and under some conditions from there into plants.
Knowing that pathway exists gives us another reason to pay attention to where our soil amendments and irrigation water come from.
The Kitchen Cannot Erase the History of the Plant
Once food enters the kitchen, we can still change some of what happens, but washing, peeling, cooking and fermentation all have limits.
Washing can remove dust, soil particles and certain substances remaining on the surface of produce. Peeling may remove material concentrated in outer tissues, while heat can change some chemical compounds and leave others almost untouched.
The important distinction is whether the substance remained on the plant or actually entered the plant while it was growing.
Something sitting primarily on the surface of a leaf may be reduced considerably with washing. A compound that entered through the roots and became distributed through plant tissues is beyond the reach of the sink, and a metal incorporated into plant tissue does not vanish because we soaked the vegetable.
Fermentation gives us another interesting possibility because microorganisms possess enzymes capable of transforming many compounds. Research with sauerkraut organisms and other microbial communities shows that biological transformation of environmental compounds can occur, but fermentation should never be treated as a promise that contaminated food can automatically be made clean.
We still need to know what organisms are present, which compound we began with, the concentration involved and what metabolites appear afterward. A disappearing parent compound may simply have become another molecule.
Microbes perform astonishing chemistry, and respecting them means respecting their limits too.
Then It Reaches the Human Microbiome
The meal eventually enters another microbial ecosystem, and this one is living inside us. Our digestive tract contains an enormous community directly interacting with plant fibre, resistant starch, polyphenols, proteins, fats and thousands of compounds arriving through food.
Those microbes create metabolites that participate in our intestinal environment, immune communication and metabolism. Environmental compounds arrive in the same digestive system, though some are absorbed earlier while others travel farther into the intestine.
Some interact with mucus or bile, some meet microbial enzymes and some appear capable of changing microbial metabolism or community structure. Research into these relationships is still surprisingly young compared with the length of time human beings have already been exposed to modern industrial compounds.
That gap concerns me.
Thousands of synthetic compounds have entered agriculture, packaging, food production, water systems and household life while we have known remarkably little about how they interact with the enormous microbial ecosystem inside the human body.
Research involving PFAS has added another curious piece. Some human gut bacteria appear capable of accumulating per- and polyfluoroalkyl substances inside their cells, and different bacterial species do not all behave the same way. Other research involving agricultural chemical exposures has found changes in microbial composition or metabolism under particular experimental conditions.
Our microbes are physically encountering the chemistry of the modern world.
The microbial community that developed in relationship with plants, animals, food, soil and other humans is now also meeting industrial residues, plastic-associated compounds, agricultural chemicals, pharmaceutical residues, food additives and mixtures that did not exist through much of human history.
We should be taking that much more seriously.
What Are We Doing to the Human Microbiome?
For decades, health conversations focused heavily on individual nutrients, individual organisms and individual diseases while paying remarkably little attention to the ecosystem living inside us. We are now discovering how deeply this microbial community participates in digestion, immune communication, intestinal integrity, metabolism, neurotransmitter chemistry and the transformation of plant compounds.
At the very moment we are beginning to understand the importance of this ecology, we are dramatically changing the conditions in which it lives.
Industrial food processing has changed what reaches the intestine. Fibre intake has changed, chemical exposure has changed and daily contact with soil, animals and natural environments has changed. The human microbiome is receiving a different world from the one that shaped the relationship between humans and microbes over generations.
Chemical exposure belongs inside that discussion. We cannot claim that every modern compound damages the microbiome, because the evidence does not support something that broad. We can say that many environmental and food-related compounds are capable of interacting with gut organisms, influencing microbial metabolism or changing community structure under particular conditions.
Seen from the larger ecological picture, we are applying pressure to microbial ecosystems at both ends of the food chain.
The soil microbiome is dealing with disturbance, chemical inputs, polluted materials, declining organic matter and loss of biological diversity. The human microbiome is experiencing another form of ecological change through industrialized food, environmental contaminants and lifestyles increasingly removed from the microbial environments in which human beings developed.
Microbial ecosystems can adapt and recover, just as soils and forests can. Repeated disturbance without enough opportunity for recovery changes what can live there and how that ecosystem functions.
Weakening microbial communities in the soil and inside ourselves means weakening two biological foundations that are far more connected than we were taught to believe.
We Rarely Encounter One Compound at a Time
Laboratory science needs to simplify the world so individual effects can be understood. Researchers may expose cells, plants, microorganisms or animals to one carefully measured compound because introducing many variables at once makes cause and effect extremely difficult to identify.
Living systems receive something far messier.
A field may contain residues from several agricultural products together with metals, microplastics and naturally occurring plant compounds. Irrigation water may bring another group, while a meal can contain food additives, packaging-related compounds, environmental residues and hundreds of chemicals made naturally by the plants themselves.
The person eating the food arrives with another history of previous exposures, diet, medications, age, microbial community and environment.
Some compounds may have additive effects, while others influence the absorption or metabolism of neighbouring substances. Many combinations have barely been studied because the possible mixtures quickly become enormous.
Nobody can realistically test thousands of compounds in every possible combination, concentration, life stage and microbiome. Large areas therefore remain where we simply do not know what repeated low-level mixtures are doing.
Uncertainty does not prove that every mixture is dangerous. It does mean that absence of evidence should not automatically be translated into proof of safety either.
The living system receives the whole mixture.
Dose Matters, and So Does Time
Modern analytical instruments can detect astonishingly tiny amounts of substances, and finding a molecule does not automatically mean that the concentration is biologically important. Dose, frequency, duration, timing, chemical form and route of exposure all influence what happens.
A trace exposure encountered once is very different from a persistent compound entering the body repeatedly over years. Something quickly transformed and excreted creates another biological situation from a substance that accumulates in tissue, while exposure during development can have very different implications from the same amount encountered later in life.
We do not need fear every laboratory detection, and we also should not use that fact to dismiss persistence or repeated exposure. I want to know how much is present, how often the exposure occurs, whether the compound accumulates, what it becomes and which biological community is being asked to process it.
Those questions move us much closer to understanding the actual risk than either panic or dismissal.
Rebuilding Biological Resilience
I have little interest in responding to all of this by becoming frightened of soil, plants or food. I am much more interested in rebuilding the biology that gives living systems their ability to respond.
A diverse soil food web cycles nutrients, builds aggregates, holds organic matter and participates in the transformation of compounds entering the soil. Roots continually alter the chemical environment around themselves, and plants have elaborate metabolic systems of their own.
Inside us, the liver, kidneys, intestinal tissues and microbial community are also constantly processing what arrives through food and water. None of these systems works in isolation, and all of them need suitable conditions.
Soil losing living roots, fungi, organic matter and plant diversity while facing repeated chemical stress has fewer biological resources available for recovery. The microbial community inside us also needs nourishment, particularly diverse fibres, resistant starches and plant compounds that can feed microbial metabolism.
I keep returning to the same questions when working with soil: What feeds the community? Where is its habitat? Is there enough diversity? Are we creating conditions in which the organisms can actually perform the work we expect of them?
Those questions belong inside the human microbiome conversation too.
We have become very good at correcting individual symptoms while allowing the ecological foundation underneath them to weaken. Rebuilding that foundation gives biology something to work with again.
What Can We Actually Do?
Knowing the history of the land is a practical place to begin. Former industrial activity, dumping, intensive agriculture, mining, heavy traffic, old painted buildings, treated timbers and contaminated waterways can all give us clues about which contaminants might be worth investigating.
Water deserves the same attention because clear does not necessarily mean clean. Irrigation water may come from wells, rivers, springs, municipal systems, reservoirs or reclaimed wastewater, and each source carries its own chemical and biological history.
Compost asks us to look backward too. I want compost alive and biologically rich, but I also want to know what went into it because composting cannot make every persistent compound, metal or plastic fragment disappear.
Manure carries the history of the animal, its food, water, environment and whatever substances it encountered before that material reached the garden.
Plastic is another place where very simple decisions can help. Agricultural plastics can be recovered before they fragment, damaged material can be removed and unnecessary plastic contact with soil can be reduced where practical.
Then we can give the microbial community something better to work with: living roots, plant diversity, biologically active compost, clean organic matter and protected soil structure.
Known contamination may require more specific action. Certain plants can accumulate some metals and root-associated microorganisms can participate in transforming particular organic contaminants, but material used to remove a contaminant has to be managed carefully afterward or we simply send that contaminant around another lap of the cycle.
Laboratory testing, changing a water source, stopping an input or physically removing contaminated material may sometimes be exactly what the land needs. Working biologically does not mean refusing measurement. It means using the information to make better decisions for the living system.
Follow the Molecule
Imagine a molecule arriving in a field after something has been applied to the soil. Rain falls later that afternoon, dissolving part of it into the thin films of water surrounding soil particles while another portion binds to clay or organic matter.
Some begins moving downward and another fraction remains near the surface where roots and microorganisms are already active. A root grows through that area several days later, and whether our molecule remains attached to soil, approaches the root or enters plant tissue depends partly upon its size, electrical charge, solubility and chemical structure.
Around that root lives the rhizosphere community, feeding on compounds released by the plant and continuously altering the chemistry of its microscopic environment.
One bacterium encounters our molecule and has an enzyme capable of changing part of its structure. The original compound becomes a metabolite, and another organism later changes that metabolite again.
The molecule we started with has disappeared, yet its chemical story is continuing.
The new compound might attach more strongly to soil or become easier for water to carry. Another portion may reach a root before microbes transform it, allowing plant enzymes to alter it and retain some inside root tissue while a smaller fraction travels upward.
Weeks pass and the crop is harvested. Material remaining on the plant surface may be partly removed during washing, while anything that entered the plant’s tissues remains out of reach of the sink. Chopping changes plant structure, heat may change part of the chemistry and fermentation introduces another microbial community.
Then the meal is eaten.
Stomach chemistry, enzymes, bile, food and microorganisms become part of what happens next. Some compounds are absorbed, while others travel farther through the intestine where gut organisms may transform them, bind them or leave them largely alone.
Material entering the body eventually has several possible futures. Part can leave through urine or stool after our own metabolism has changed it again, while persistent material may remain longer before it is excreted.
Now the waste enters another system.
It may travel through wastewater treatment or belong to an animal and become manure. Perhaps the manure is composted and spread onto agricultural land, carrying the molecule, one of its metabolites or another chemical descendant back toward soil.
This is what I find so fascinating and concerning at the same time. Human-made compounds can enter many of the same pathways through which carbon, minerals, plants, microbes and ourselves are already connected.
When someone tells me that a chemical has disappeared, I want to know what that actually means. Where did it go? What did it become? Which organism encountered it next?
Following the molecule tells us much more than simply asking whether we can still detect the form in which it began.
Soil to Microbiome and Back Again
Human activity has altered the microbial world beneath our feet before we fully understood how important that world was. We have altered the microbial world inside ourselves during the same period, while only recently beginning to appreciate how deeply that ecosystem participates in human physiology.
Soil microbes are involved in fertility, decomposition, mineral cycling, water relationships, soil architecture and the conditions in which our food grows. Human microbes participate in digestion, metabolism, intestinal health, immune communication and the transformation of compounds carried by that food.
These communities are part of the foundation.
They also possess an extraordinary ability to adapt, reorganize and transform materials, but we should not confuse resilience with unlimited tolerance. Repeated contamination, disturbance, loss of habitat and declining diversity eventually change what an ecosystem is capable of doing.
I would much sooner use what we are learning to rebuild microbial life.
In soil, that means clean organic matter, living roots, diverse plants, protected fungal networks and greater awareness of what enters through water, manure, compost and agricultural materials. In ourselves, it means remembering that our microbial partners need nourishment too, including diverse plant fibres, resistant starches and the enormous range of compounds carried in real food.
The connection between those two worlds is not theoretical. The soil microbiome helps create the conditions in which the plant grows, the plant becomes our food, the food enters the human microbial ecosystem and some of what leaves humans and animals eventually returns to water and land.
The cycle continues whether we understand it or not.
If we keep damaging the microbes at both ends of that journey, we are weakening the living foundation connecting the soil to ourselves. If we begin rebuilding those microbial communities, we give the whole cycle a greater capacity to function, adapt and recover.
That may be one of the most important pieces of the health conversation we have been missing.
