Why Soil Health Is Important for Human Health

  • Outdoor America
  • Cover Story
Farmers market in Annandale, Va. - credit Michael Reinemer

How we treat the land affects how the land treats us.

The science is increasingly clear: poor soil health translates into less healthy crops and farm animals. And that leads to less healthy food for people.

A typical American dinner, even one with a variety of food groups and fresh vegetables, may look like a bounty of nourishing food. But in critical ways, the typical diner today is getting shortchanged.

Harvesting Health for People

Over the past century, changes in how we grow what we eat have inadvertently undermined our health. Today, we need a unified theory of agriculture and nutrition built on a common foundation of soil health to deliver prosperity to farmers and well-being to eaters.

A good place to start centers on broadening how we think about and define nutrients. Phytochemicals with anti-inflammatory and other benefits are crucial in this regard. They provide a basic array of diet-based tools to fix and repair small problems in our bodies before they turn into more serious or chronic ailments, especially as we age.

Researchers have been establishing that phytochemicals and a new class of “longevity vitamins” are compounds essential for routine maintenance of our bodily systems. These compounds are not nutrients in the classic sense. They are not the fuel or elements that run and build our physical body. But they do help keep our bodies running smoothly. This in turn plays a big role in preventing the rise and progression of chronic diseases rooted in inflammation and damage to our DNA and cells caused by oxidation.

Our current overly narrow focus on high yields at the expense of soil health and nutrient density means that in seeking to solve hunger we’ve been shortchanging our health. Given the prevalence of chronic diseases and deficiencies in micronutrients (such as iron, zinc, vitamin D), we would be wise to look at the potential for improved farming practices to enhance human health. Farmers should have incentives to deliver nutrient-rich foods as well as caloric volume.

It’s not really a question of quality versus quantity. Regenerative and organic farm practices can deliver yields comparable to conventional agriculture while improving soil – and producing healthier crops and farm animals that support human health.

What Your Food Ate - credit Michael ReinemerThis new book by David Montgomery and Anne Biklè explores the role of soil health in human health.

What Your Food Ate

Naturally, a lot of factors affect human health, like our genes, exercise, lifestyle, and what we choose to eat. But in researching our new book, What Your Food Ate, we concluded that how we grow our food also affects our health.

We generally don’t think of crops as having a diet. But they do. Soils that are healthy and rich in organic matter provide plants with a profoundly different diet compared to soil where chemical fertilizers have been used in conventional agriculture. This difference affects gene expression in plants and therefore the relationships they carry on with the soil microbiome.

Beneath our feet, crops can form symbiotic relationships with beneficial bacteria and fungi that transfer vital nutrients from the soil to plants we eat, or to forages that farm animals eat. So more health-promoting nutrients are delivered to people through these pathways.

The upshot is that healthy, fertile soils imbue our crops and livestock with micronutrients and phytochemicals, which in turn help reduce the risk of chronic diseases in people. Conventional farming practices, however, have undermined the biological processes that get these and other beneficial nutrients into our crops – and thus our bodies.

Whether in urban, suburban or rural areas, we all should care about farming practices and policies. Unfortunately, most current regulatory programs and incentives do not reward agricultural practices that build and safeguard soil health. Instead, we subsidize conventional practices that degrade soil health and lead to over-reliance on synthetic fertilizers and pesticides.

To make meaningful changes that benefit consumers broadly, we need to invest in and support more soil-friendly farming. The bottom line is simple – agriculture policy is health policy.

When Inflammation is Dangerous

Inflammation is a normal part of a healthy immune system. A part of our body swells up around a cut, for example, because white blood cells concentrate in the area to fight infection or help with healing.

But chronic, unending inflammation in otherwise healthy parts of our bodies, including critical internal organs like our heart, brain and liver, is a factor in serious conditions such as heart disease, Alzheimer’s and cancer. So chronic inflammation is more than a nuisance – it can be lethal, and diet plays a role in reducing or exacerbating the problem.

Grain-fed cattle produce meat and milk with a high level of omega-6 fats that initiate chronic inflammation. Beef and milk from pasture-raised dairy cattle, by contrast, contain more omega-3 fats, which are key to ending inflammation after its work is done. This is because the leaves of living plants, like grass growing in a pasture, are rich in omega-3s, whereas seeds – like corn or soybeans – are rich in omega-6s.

How Farming Practices Affect Nutritional Value of Food

In traditional farming, the soil is broken up (tilled) for weed control and planting seeds. Conventional farmers today further rely on copious applications of soluble nitrogen fertilizers to prop up yields, as well as herbicides like glyphosate (the key ingredient in Roundup weed killer). In contrast, a regenerative combination of practices based on diverse crop rotations, reducing if not eliminating tilling, and planting cover crops to hold soil in place and nourish soil life allows conventional farmers to greatly reduce or even eliminate their use of chemical fertilizers and pesticides.

In urban, suburban or rural areas, we all should care about farming practices and policies.

In a way, synthetic nitrogen fertilizers used in agriculture today are an example of too much of a good thing. They dramatically boost plant growth, and thus crop yields, especially in degraded soil. But when applied liberally, soluble nitrogen fertilizers scuttle communication between a plant and beneficial communities of soil life – and undermine fungal symbioses in particular. Plants get lazy when spoonfed nitrogen. So they don’t invest in as extensive a root system for recruiting and feeding their microbial partners. And this reduces crop uptake of mineral micronutrients and other beneficial compounds essential to plant health, and ours.

Routine tillage also affects soil life. A review of more than 100 scientific papers found that plowing, or tilling, profoundly disturbs the rich array of life inhabiting fertile topsoil. Once again, fungi that fetch minerals for crops are among the most disturbed as tillage slices and dices their networks to the point that they significantly curtail nutrient deliveries to their plant host.

Minerals are not the only things that conventional practices affect in crops. Important phytochemicals, such as carotenoids and polyphenols, are key reasons why soil health matters to people. Phytochemicals are compounds plants make for their own health, communication and defense – in response to soil life and other environmental conditions. So the state of the soil can influence their abundance in plant foods.

Loads of studies reporting health benefits of fruits and vegetables ascribe beneficial effects to the phytochemicals they contain. For example, many phytochemicals have anti-inflammatory effects or serve as signaling molecules that tee up or inform our immune system. And physical or chemical disruption of communities of soil life can reduce the phytochemical content of crops.

The bottom line is simple – agriculture policy is health policy.

In 2014, the British Journal of Nutrition published an analysis of 343 peer-reviewed studies that found significantly greater levels of phytochemicals in organic crops, meaning they were grown without synthetic fertilizer or pesticides. It also found higher concentrations of pesticide residue and the heavy metal cadmium in conventionally grown crops. The study revealed that you would have to consume about twice as much conventional produce – pesticides and all – to get the same amount of phytochemicals as produce grown in healthy soil.

What our livestock eats matters too. Particularly important is the balance of fats in meat and dairy products. Beef and milk from pasture-raised dairy cattle contain more omega-3 fats, which are key to helping quell on-going inflammation, a major contributing cause of many chronic diseases. In contrast, grain-fed cattle produce meat and milk with far greater levels of omega-6 fats, a type that initiates inflammation. This is because the leaves of living plants, like grass growing in a pasture, are rich in omega-3s, whereas seeds – like corn or soybeans – are rich in omega-6s.

An omega-6 to omega-3 ratio of around two to one is considered optimal for human health. That is about the ratio in most wild game. Today, however, conventionally raised meat and dairy typically have ratios higher than 10 to 1. Our modern diet is awash in omega-6s. And what our food eats we become. Is it a coincidence that chronic diseases rooted in inflammation plague so many of us?

In other words, what your food ate influences what a meal does for – and to – you. Consumers deserve to know more about the soil their food originates in and how it influences the nutrient-density and other benefits of the food they buy.

David Montgomery signs copies of his book - credit Michael Reinemer David Montgomery signs What Your Food Ate for attendees at the League's national convention.

Soil Solutions

Regenerative farming practices that combine no-till methods with growing a diversity of cash and cover crops produce a substantial array of benefits. The combination reduces the need for and expenditures on fertilizers and pesticides. It also helps to keep healthy topsoil in place, reducing runoff of agrochemicals and sediment that pose dangers to drinking water and public health.

While it is no panacea, soil-health building farming practices can reduce agricultural carbon emissions and stash atmospheric carbon underground where it becomes an asset rather than a liability. Though estimates vary greatly of just how much carbon can be returned to farmland soil this way, agricultural practices that build soil carbon offer real opportunities to help address the climate crisis.

So as we work to provide food for humanity today, just how well are we providing nourishment? We need to focus on both quantity and quality. And improving soil health is a well-supported means to do both.

In particular, providing consumers with information on nutrient density beyond the basics presented on labels today would allow the market to provide economic incentives for farmers to deliver nutrient-dense food while providing a host of benefits in terms of conservation – cleaner water and air, healthy soil and greater carbon sequestration.

Our agricultural policies and practices should be founded on the view of the soil as a sacred trust we pass forward for future generations. Such framing would help create the economic mechanisms that reward farmers for improving their soil rather than subsidizing conventional practices that degrade soil.

Will healthy soils alone ensure our health? Of course not, a lot more affects health. But a diet of fresh whole foods grown in healthy soil provides our bodies with what they need to work normally and to stay as healthy as we can.

And in this sense, food grown in healthy, fertile soil can serve as preventive medicine. For it turns out that what’s good for the land is good for us too.

Just How Much More Nutrition?

A comparison of 10 pairs of neighboring regenerative and traditional farms around the country found consistently better soil health on the regenerative farms – and higher levels, on average, of certain vitamins and phytochemicals.

Vitamin K +34% (needed for blood clotting and building bones)
Vitamin C +17% (needed for growth, development, and repair of tissues)
Vitamin E +15% (important to vision, and health of blood, brain, and skin)
Vitamin B1 +14% (helps metabolize fats and protein)

Carotenoids +15% (antioxidant and anti-inflammatory effects)
Phenolics +20% (antioxidant and anti-inflammatory effects)
Phytosterols +22% (reduced cholesterol absorption)

Learn more about our work for healthy soil

Top photo: In a sense, food grown in healthy, fertile soil can serve as preventive medicine. It turns out that what's good for the land is good for us too. Farmers market in Annandale, Va. Credit: Michael Reinemer.

David R. Montgomery, Ph. D., and Anne Biklè are authors of What Your Food Ate: How to Heal Our Land and Reclaim Our Health. They also wrote The Hidden Half of Nature.