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How Does Nutrient-Depleted Soil Impact Our Food, and What Can We Do to Fix It?

by Katie Melville, Ph.D.

Published on

Nearly 99 percent of the world’s daily calorie intake can be traced back to soil. (1) The plants we eat require soil to grow, and the animals we eat require plants to grow. Soil is vital for human survival, yet modern farming and agricultural practices are quickly destroying it. Worldwide, one-third of the Earth’s soil is at least moderately degraded, and over half of the land used for agriculture has some level of degradation. (2)

depleted soil
Industrialized agricultural techniques have contributed to nutrient depletion in soil. iStock/mladenbalinovac

Due to intense, mismanaged farming, soil nutrients are declining. Nitrogen stores have decreased by 42 percent, phosphorus by 27 percent, and sulfur by 33 percent. (3) To grow optimally, plants require these nutrients for photosynthesis, enzymes, protein synthesis, and more.

As a result of declining soil fertility and selective breeding, the nutritional contents of some fruits, vegetables, and grains have also been compromised. In a 2004 study, 43 garden crops were analyzed to compare nutritional content in 1950 versus 1999, using USDA data. Some nutrients were unchanged, but calcium, phosphorus, iron, riboflavin, and vitamin C were all lower in 1999 compared to 1950, ranging from a 6 percent to 38 percent drop. (4)

Almost 99 percent of the world’s daily calorie intake can be traced back to soil—and that’s a problem as soil depletion becomes more common. Check out this article from Katie Melville to find out more. #nutrition #optimalhealth #wellness

Consider the following additional data:

  • The protein content in corn declined 30 percent to 50 percent from 1920 to 2001, while the starch content increased. (5)
  • The magnesium content of vegetables and wheat has declined by up to 25 percent. (6)
  • Trace minerals in vegetable crops, including manganese, zinc, copper, and nickel, have decreased over the last several decades, while toxic minerals like aluminum, lead, and cadmium have increased. (7)

These numbers are worrisome, and we should re-examine our farming and agriculture practices to preserve the soil’s fertility.

Industrial Agriculture Increases Yields but Leads to Soil Erosion and Nutrient Depletion

There’s no question that intensified agricultural practices since the mid-20th century have increased crop yields, but it’s being done at the expense of future food security.

Current industrial agriculture is destroying the soil at 100 to 1,000 times the rate at which it can be replenished. (8) According to United Nations estimates, we have only about 60 years left of harvests in many farming regions—and then what? (9)

The following are some of the modern farming methods that contribute to soil erosion.

Synthetic Fertilizers

Instead of using organic fertilizers, including crop rotations, cover crops, and manure, modern farms require massive amounts of synthetic fertilizers to continually grow crops. Nitrogen-based fertilizer production has increased by 9.5-fold since 1960. (10) In a very energy-intensive process, fertilizer production consumes fossil fuels, with non-negligible environmental consequences. (11)

Not all the fertilizer applied is taken up by the crops. Fifty percent or more of the nitrogen leaches into the environment. Inorganic fertilizers destroy soil microbes, which play vital roles in soil homeostasis and nutrient levels. (12) Ammonia, nitrate, and other nitrogen residues make their way to groundwater, rivers, and eventually, the ocean, where they contribute to reduced oxygen levels, increased algae growth, and damage or death to aquatic life. (13, 14)


Many industrial farms grow one single crop, year after year after year. This practice depletes the soil of nutrients and contributes to soil carbon loss and soil erosion. Ideally, agriculture farms should include legumes, perennial crops, and forages in rotation to return more organic matter to the soil, to prevent erosion, and to replenish nutrient levels. For example, legume crop residues can be converted into nitrogen by soil bacteria, reducing the need for synthetic nitrogen-based fertilizers. (15)

Additionally, monocropping can threaten food security. With a single species of crop on millions of acres, one disease could potentially wipe out an entire food system.

Tillage-Based Farming

Farms today till fields to remove crop residues, flatten the land, and generally mix up the topsoil. However, tilling reduces microbe populations in the soil, promotes soil erosion, and releases greenhouse gases. Today, 93 percent of the world’s cropland uses tilling-based methods for production. (16, 17)

Herbicides, Pesticides, and Fungicides

Herbicides, pesticides, and fungicides can help increase crop yield by keeping weeds and harmful organisms under control. However, those benefits come with costs. Pesticides that kill bugs and disease-causing microbes can also destroy the instrumental microbial populations in the soil. Pesticides can also disrupt honeybee and butterfly populations, with negative impacts on pollination (18, 19)

Additionally, pesticide residues make their way into water systems and food. A long list of health problems has been linked to pesticide exposure, including asthma, neurological issues, and even cancer. (20, 21) The most well-known herbicide is glyphosate, which is applied to crops in hundreds of millions of pounds each year. (22) Glyphosate has profound environmental and health consequences, covered in depth in this article.

Mismanaged Grazing

Cows and other ruminants have the amazing ability to convert grasses and other plants that are inedible for humans into nutrient-dense, edible animal products. Best practices dictate that ruminants should rotate among different fields, allowing sections of grass to rest and regrow. But when cows graze continually on the same land as in many conventional farms, it contributes to soil erosion and lowers soil carbon reserves. Overgrazing like this has contributed to the loss of about one-fifth of the world’s grasslands. (23)

Unfortunately, the importance of ruminant animals has been almost forgotten. Much of the world’s land isn’t even conducive for growing crops, due to rocky terrain, hills, and climate. (24) In contrast, cows, sheep, and goats can often thrive on these marginal lands. Yet these areas aren’t being fully utilized to raise ruminants for food and to properly sequester carbon. Instead, we have concentrated animal feeding operations, or CAFO, where grazing is limited and cows are fed grain residues from a faraway farm.

Fertilizers, monoculture, tilling, pesticides, and mismanaged grazing contribute to soil erosion, which increases greenhouse gases and increases the need for irrigation due to the lost water capacity of the soil. Most agricultural soils lose half of the sequestered carbon in the ground after just 25 to 50 years of harvests. (25) These intense, modern farming practices increase yields temporarily but are short-sighted.

How to Fix the Farming System

Soil, microbes, plants, and animals evolved together as an ecosystem, but industrial farming isolates either one crop or one animal type and converts it into an enormous production system. Instead of these large, specialized farms, the future of farming should contain more numerous, smaller-scale operations that incorporate both organic, mixed crop farming and grazing animals. This type of transformation can’t be done overnight, but the gradual changes needed include the following.

Bring Back the Ruminants

Ruminants like cows turn grass into nutrient-dense animal products. Properly rotated grazing herds stimulate good root systems that sequester carbon and increase the water-carrying capacity of the soil. Manure can be collected and used for nearby cropland, lowering the need for synthetic fertilizers.

Ditch the Monoculture Model

Well-managed cropland should include legumes, perennial crops, and forages in rotation to increase soil fertility, reduce soil erosion, and increase carbon sequestration. (26)

Fix Fertilizer

Natural fertilizers like cow manure return carbon directly back to the ground. In contrast, chemical fertilizers are produced in factories that contribute to greenhouse gas emissions. Crop residues should be returned to the soil to allow nutrient replenishment.

Farm Organically

Yes, organic is better. Organic, sustainable farming yields products higher in micronutrients and lower in pesticides while being better for the environment. (27, 28)

To save our soil and ensure future food security, the farming system needs a complete overhaul.

Whole Foods Instead of Whole Grains

The top three crops grown in the United States are corn, soy, and wheat. (29) Since 1961, cereal production has increased by nearly 400 percent, yet obesity, diabetes, and other health problems have only skyrocketed. (30) The problem is that grains, soy, and corn are low on the nutrient density scale, far below organ meats, meat, eggs, dairy, vegetables, and fruits. (31) Farms are producing nutrient-poor foods on a wide scale—and it’s killing us.

The human body requires around 40 different micronutrients for normal function, but most Americans eat nutrient-poor diets full of processed grains, industrial seed oils, and refined sugars, by design of the agricultural system. This puts us in danger of nutrient deficiencies. Although 42 percent of adults in the United States are overweight or obese, nearly one-third of Americans are at risk for at least one vitamin deficiency or anemia. (32, 33) We’re overfed, yet undernourished.

We need to shift our farms and diets from processed junk to nutrient-dense, real, whole foods that are produced on sustainable, organic farms. The subsidies for corn, wheat, and soy need to stop, and instead, we need to figure out creative ways to make nutrient-dense foods more available and affordable. Gradually, we have to change farming from the inside out.

Plant-Based vs. Paleo: How about Both?

Mainstream media are quick to vilify beef production (of any kind), yet sing praises for vegetarian or vegan diets that rely heavily on monocultures that destroy the soil. Yes, cows raised in confined, concentrated farms fed residues from one-crop farms are detrimental to the environment. But what you won’t hear on the news is the amounts of greenhouse gases released on industrial agriculture lands. Large, single-crop farms without grazing animals destroy the environment, too, due to soil erosion, fertilizer production, and irrigation.

However, when animals and agriculture are integrated, a sustainable farm can be net carbon positive, meaning it returns carbon to the soil instead of releasing it into the air. In a mixed crop and grazing agroecosystem such as this, three to eight additional tons of carbon per hectare per year can be sequestered. (34, 35) The answer to climate change isn’t veganism or lab-grown meat; instead, the answer lies in sustainable farms where crops, animals, and soil are integrated for mutual benefits.

Other Resources for Sustainable Farming

To learn more about sustainable farming, check out the following:

Katie Melville
Katie Melville, Ph.D.

Katie Melville earned a Ph.D. in Biomedical Engineering from Cornell University, where she studied the mechanisms of bone formation and resorption. In particular, she elucidated the effects of sex hormones and their receptors on bone mass and architecture. She also researched estrogen's role in bone's response to mechanical loading. She has co-authored several peer-reviewed research papers, written book chapters, and has presented at national conferences, including those held by the Orthopaedic Research Society and the American Society for Bone and Mineral Research.

Her interest in Ancestral Health and Functional Medicine began over a decade ago, when she started following Chris Kresser's articles and podcasts. Over the years, she has made significant changes to her family’s lifestyle, including adopting a Paleo diet template, installing a reverse-osmosis water filter, and incorporating a standing desk into her office space.

Since 2016, she has been honored to be a writer and researcher for Chris Kresser and Kresser Institute, relying on peer-reviewed literature and incorporating Chris's clinic experiences into her articles. Katie strives to understand the current knowledge surrounding human chronic disease, and enjoys digging deep into the scientific literature. She believes the future of healthcare lies in functional medicine.

Katie has also written for Natural Womanhood, a popular website that shares the benefits of fertility tracking and using natural, fertility awareness-based methods of birth control. For continued education, Katie has completed online courses from Stanford on scientific writing and how to critically interpret clinical trials.

Professionally, Katie works for Recruitomics Biotalent Consulting as a Scientific Recruiter for start-up biotech companies in the Boston area. Being in this role exposes her to the latest technological and medical


She lives near Boston with her husband and 3 young children, and she enjoys powerlifting and cooking in her spare time.

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