Soil Health 101: Everything You Need to Know
What is Soil Health?
Soil, particularly healthy soil, is a living, breathing organism, rich with billions of healthy bacteria, fungi, and other microbes that all play unique roles to create delicate and exquisite self-sustaining ecosystems.
It not only creates nutrient-dense, abundant crops, but plays a critical role in the health of our environment with its ability to sequester carbon and create cleaner air, and water.
While healthy soil’s role in food and the environment was (and still is) no secret to Indigenous communities, there has been a public rise in conversations about soil health over the last two decades due to its ability to be more sustainable and to help fight climate change.
Right now, a third of the world’s soil is moderately or highly degraded thanks to deforestation, unsustainable conventional agriculture practices like tilling and chemical-dependent farming, overgrazing, urban expansion, as well as, industrial and chemical pollution.
What this means is there is a significant threat to the world’s food supplies and there have been and will be increases in carbon emissions. Currently, in areas with conventional agriculture, a lot of the nutrients needed to sustain our health are already drained from the produce.
However, though systemically there is still a lot of work to do, more and more solutions-makers are stepping up to create sustainable change in terms of soil health, and there are steps you can take too.
First some facts and history.
- Just a single teaspoon of rich garden soil can hold up to one billion bacteria, several yards of fungal filaments, thousands of protozoa, and tons of nematodes.
- Dirt is not the same thing as soil. Dirt is not alive like soil, and is comprised of sand, silt, and clay. It has none of the minerals, nutrients of living organisms found in soil.
- Cover crops are a necessary component to protecting healthy soils. Cover crops slow erosion, improve soil health, enhance water availability, smother weeds, as well as help control pests and diseases.
- Soil quality is directly linked to food quality and quantity, according to the Food and Agriculture Organization of the UN. Soils supply the essential nutrients, water, oxygen and root support that food-producing plants need to grow and thrive, that in turn helps provide nutritious food to help people do the same.
- According to the USDA, healthy soil captures and stores water, which reduces the risk for both flooding, and can serve as a boon during droughts. Healthy soil also filters water, and replenishes aquifers, which are integral for our drinking water.
- Healthy soil stores vast quantities of carbon and plays an integral part in the global carbon cycle. Scientists say more carbon resides in soil than in the atmosphere and all plant life combined; there are 2,500 billion tons of carbon in soil, compared with 800 billion tons in the atmosphere and 560 billion tons in plant and animal life.
- Cover crops are a necessary component to protecting healthy soils. Cover crops slow erosion, improve soil health, enhance water availability, smother weeds, as well as help control pests and diseases.
- Over the years, the world’s soils have lost between 50-70% of their carbon due to unsustainable agriculture methods. This mismanagement of soil has contributed to climate change with much of that carbon released into the atmosphere as carbon dioxide.
- Topsoil is the top layer of soil that contains all the necessary nutrients for your plants. Nearly half of the world’s topsoil has been lost in the last 150 years due to these same unsustainable agriculture methods.
- According to the Food and Agriculture Organization, sustainable soil management has the potential to produce up to 58% more food.
Conventional Farming and Soil Health
Conventional farming, also known as “modern farming” or “industrial agriculture” is large-scale farming methods that arose in the mid-20th century intended to meet the needs of a rapidly growing population, and to this day is the prevailing source of the food we eat today, particularly in the United States.
In over a half a century, the World Bank estimates that between 70 and 90 percent of the recent increases in food production, was the result of conventional agriculture, which is characterized by large scale monoculture, intensive tilling of the soil, chemical fertilizers, pesticides, herbicides, and the usage of GMOs.
All of this comes at a high cost to public health, the health of agricultural workers, and the environment by polluting the air, water, and soil.
Monoculture in the U.S. and the Effect on Soil Health
Growing one crop enables farmers to increase their efficiency to plant and harvest with machinery. However, this type of agriculture increases the risk of disease and pest outbreaks, because it lacks diverse plants and animals that can limit the spread through predation, which leads to a larger usage of pesticides and herbicides compared to a diverse crop system.
By growing the same crops year after year, it also reduces availability of certain nutrients in the food by degrading the soil.
Intercropping and polyculture does the opposite.
For example, a number of Indigenous tribes plant corn, bean and squash, which grow symbiotically to deter weeds and pests, all while nourishing the soil to provide all the nutrients the plants need without fertilizer. Squash and corn take the nitrogen, but the beans give it back.
Indigenous communities cultivated biodiversity with a deeply intimate connection to the land for centuries until the Europeans came, and upended their sustainable and diversified methods in favor of monoculture.
Early on large plantations in the South would grow sugar, cotton, and tobacco for the European market all of which were labor intensive, and utilized slaves to do the work. These monocrops often resulted in soil exhaustion.
In Montgomery, Alabama in the 1700s and early 1800s, where the cash crop was tobacco, the soil at one point became so depleted, there was a severe loss of topsoil and by 1840 it became a “vampire crop” whose growth was halted by nature.
Tilling leads to a loss of rich topsoil, since tilling breaks down the fungal components that stabilize the soil, and plowing, which is a type of tilling, has led to the pervasive loss of rich topsoil, first evident in the days of the Dust Bowl, which was the name given to the drought-stricken southern plains in the 1930s.
This Dust Bowl era began because of poor agricultural practices led by inexperienced farmers, who moved to the Great Plains after settlers were incentivized through post-Civil War federal land acts that promised them 160 acres of public land.
The Great Plains were semi-arid, but those who moved there believed that the “rain followed the plow,” meaning that the settlers believed they would be able to bring the climate with them that would make things more conducive for agriculture.
The crops of the Great Plains were wheat, corn and other row crops. Millions of acres of prairie grassland that kept the soil healthy was plowed away once there became higher demand for wheat in the 1910s and 1920s. Once the price of wheat started falling during the Great Depression, however, farmers continued to tear up the land in order to plant more. Then came the drought, and with no prairie grass to keep the soil in place, it started to blow away.
The eroding soil then led to dust storms.
Inhaling the dust particles from those storms killed both people and livestock. This also caused a mass migration, with many people looking for agriculture jobs in the San Joaquin Valley in California, where agriculture changed after the Gold Rush, which destroyed a lot of land through hydraulic mining and attracted those who also violently displaced Indigenous Tribes from their diverse agriculture and food sources.
Agriculture in the San Joaquin Valley was at the behest of grasslands, oak savannah, wetlands, and forests, which were eradicated and along with them native species and microbes.
Monoculture makes soil moisture unstable, which then requires massive amounts of water to irrigate crops. The agricultural richness of the San Joaquin Valley and other areas were and are still due to massive water diversions from the northern part of the state, which has interrupted other delicate ecosystems.
It is also known for overpumping groundwater to feed thirsty crops to the point that the ground is sinking, and has brought arsenic contamination to the drinking water. Those who are the most affected are low income, from smaller towns, and the farmworkers who help grow the food.
Chemicals and Soil Health
As mentioned above, the use of synthetic fertilizers and pesticides are much more necessary with conventional farming methods.
Synthetic fertilizers are man-made combinations of chemicals and inorganic substances, typically combining nitrogen, phosphorus, potassium, calcium, magnesium and other elements to help promote the growth of the plant..
The first synthetic fertilizer was invented by two German chemists in the early 1900s, Carl Bosch and Fritz Haber. The latter would go on to create Zyklon B, a cyanide-based pesticide which was eventually used in the gas chambers during the Holocaust.
Excessive use of synthetic fertilizers has led to several issues such as soil degradation, nitrogen leaching, soil compaction, reduction in soil organic matter, and loss of soil carbon.
Pesticides can linger in the soil for years or decades after they are applied, continuing to harm soil health. Studies show impacts on soil organisms that ranged from increased mortality to reduced reproduction, growth, cellular functions and even reduced overall species diversity.
They also harm our health.
Exposure to pesticides through contact with skin, ingestion, or inhalation, depending on duration and route of exposure, can result in dermatological, gastrointestinal, neurological, carcinogenic, respiratory and endocrine issues.
Pesticide residues can also be found in lots of everyday foods and beverages, including cooked meals, water, wine, fruit juices, and animal feeds. Pesticide residues have also been detected in human breast milk samples, and there are concerns about the health effects in children due to prenatal exposure.
Greenwashing and Pesticides
Large companies are now trying to cash in on the desire for more eco-friendly products, which has resulted in greenwashing of some of their products, arguing for the use of pesticides in ‘regenerative’ or ‘climate-smart’ agriculture.
In 2020, according to Environmental Health News, nonprofit Beyond Pesticides sued TruGreen over its false claim to offer “environmentally friendly, sustainable lawn care services that use no chemicals that may cause cancer, allergic reactions, or other health or environmental harms.”
TruGreen uses glyphosate, which is a carcinogen as well as a weedkiller with a label warning of “irreversible eye damage” and “allergic reactions,” and a neurotoxic insecticide, according to Beyond Pesticides.
In 2012, Miracle-Gro also had to pay criminal fines and civil penalties for pesticide law violations, including affixing misleading labels to pesticides.
In terms of greenwashing, Dr. Aditi Dubey of the Center for Biological Diversity said, “We know that farming practices such as cover cropping and composting build healthy soil ecosystems and reduce the need for pesticides in the first place.”
Desertification could end up being a result of intensive agriculture practices, alongside drought, deforestation, overexploitation of water resources, and overgrazing by livestock or native and non-Native species that leaves the ground cover depleted.
Desertification is the process by which fertile land becomes a desert and involves areas with low or variable rainfall called drylands. Drylands account for more than 40 percent of the world’s surface.
According to the UN, about 2.1 billion people live on drylands in more than 100 countries, and 44% of the world’s cultivated systems are there, and are vulnerable to desertification, which could displace an estimated 50 million people by 2030. Those who are affected the most are poor and marginalized communities.
The European Commission’s World Atlas of Desertification also says 75% of the Earth’s land area is degraded, and more than 90 percent could become that way by 2050. The U.S. has already lost $42 billion annually from desertification and land degradation. The result of which could be food insecurity, health issues, and mass migration.
There is now an urgency to adopt mitigation practices and though it’s a global issue, it will take local solutions to fix it, which involves planting more trees, improving the quality of soil, better water management and other methods.
Soil Health and Climate Change
In 2020, 11% of greenhouse gas emissions came from agriculture. This partly involves methane emissions from livestock, but this also comes from unsustainable agriculture methods that release the carbon from soil that turns them into carbon dioxide in the atmosphere – one of the main greenhouse gasses that causes global warming.
Converting forests and grasslands into farmlands has disturbed soil structure, releasing stored carbon from the ground. This also happens with tilling, monoculture, removing crop residue, excessive use of fertilizers and pesticides, and overgrazing. Once the carbon reaches the surface and hits oxygen, it becomes carbon dioxide.
Healthy soil extracts carbon dioxide from the atmosphere through photosynthesis, some of which is stored in the soil as fresh plant residue or decomposed material called humus. These organic compounds contain carbon and are known as soil organic matter that locks carbon underground and forms the foundation for rich soil.
Many believe that healthy soil is one of the major components in mitigating climate change.
Sustainable Agriculture and Soil Health
Getting healthy soil means utilizing holistic land management. According to the UN’s Food and Agriculture Organization this will promote and enhance agro-ecosystem health that is socially, ecologically and economically sustainable, and is necessary in order to protect our soils.
In 2018, the USDA National Resources Conservation Service came out with a Soil Health Growers Checklist for healthy and productive soils. The four basic principles they write as guidelines is: minimize disturbance, maximize soil cover, maximize biodiversity and maximize the presence of living roots, and their best soil management systems include:
Conversation Crop Rotation
This involves growing a diverse number of crops in a planned sequence in order to increase soil organic matter and biodiversity in the soil. This increases nutrient cycling, manages plant pests, reduces erosion, holds soil moisture and adds diversity so microbes can thrive.
Using Cover Crops
This is an unharvested crop grown as part of a planned rotation to provide benefits to the soil, which prevents soil erosion, increases soil organic matter, conserves moisture, increases nutrient cycling and suppresses weeds.
A way to grow crops without disturbing the soil, which improves water holding capacity, reduces erosion, and increases organic matter.
Utilizes tilling methods when the soil surface is disturbed, but maintains a high level of crop residue, which reduces erosion from wind and rain, and increases soil moisture.
In soil, twenty nutrients are recognized as needed for good crop growth. They are: Nitrogen, phosphorus, potassium, sulfur, calcium, and magnesium. Plants also need micronutrients such as boron, copper, manganese, molybdenum and zinc to remain healthy. Nitrogen, phosphorus and potassium are usually needed for good yields, however, too much of any can have negative impacts with groundwater, cause algal blooms in surface water, or cause poor crop growth.
Nutrient management consists of testing the soil, determining the recommended amount of fertilizer, accounting for other sources of nutrient inputs like composts, then applying nutrients as needed.
Managing pests by following an ecological approach that promotes the growth of healthy plants with strong defenses, while increasing stress on pests and enhancing the habitat for beneficial organisms.
Ecological pest management focuses on preventive rather than reactive approaches to pest management. Reducing disturbances to soil, like tilling and the use of synthetic fertilizers which attract pests helps. Keeping soil healthy creates healthy plants, which in turn have natural defenses against pests.
Indigenous Roots of Regenerative Agriculture
Many of the sustainable agriculture practices that promote healthy soil supported by NCRS, particularly in what is filed under the regenerative agriculture movement (which has felt like a new concept over the years), is actually based in Indigenous roots and practiced for centuries. Crop rotation is one of those listed above.
In 2019, UN climate scientists declared that protecting Indigenous land rights was imperative to reversing the climate crisis. By using traditional ecological knowledge, they are protecting 80% of the world’s biodiversity.
More Indigenous farming practices that helped mold sustainable farming systems and practices internationally are:
Intensive land management system that optimizes the biological interactions between trees and/shrugs combined with crops and livestock. Benefits include protecting crops and livestock from the elements, improved soil health, controls soil erosion and creates a wildlife habitat. It also increases wealth in rural communities and creates sustainable farms, ranches and woodlands.
A system where farmers grow two or more crops at the same time, which creates biodiversity, increases soil organic matter, attracts beneficial predators to minimize pests, and suppresses weed growth.
Successful intercropping relies on growing crops that complement one another and minimally compete for resources.The principles of intercropping can also be applied to cover crops, which results in improved soil health, sequestered carbon, and the bolstering of biodiversity.
Polyculture, like intercropping, involves growing many different plant species in the same area in a way that imitates nature. Creating biodiversity in turn helps with soil quality, soil erosion and more yields. They are also more adaptable to climate and extreme weather events, and resilient to pests and disease.
Rotational grazing with livestock is a system where a large pasture is divided into smaller paddocks allowing livestock to be moved from one paddock to the other easily to avoid soil erosion.
Rotational grazing also decreases soil compaction, which is when soils become restricted with air and water movement, and soil structure changes, not allowing as much water to be retained or the amount of organic matter.
There is also better distribution of manure, which contributes to the nutrients in soil. This also provides organic matter to soils to increase plant root health and forage productivity.
Ranching was one of the reasons settlers and colonizers began to claim land from Native peoples west of the Mississippi in the mid-1800s, Ryan Fischer told Civil Eats. Fischer is a visiting assistant professor of history at the University of Wisconsin, River Falls, and the author of the book Cattle Colonialism: An Environmental History of the Conquest of California and Hawai’i.
Spanish and English colonizers brought cattle to the U.S., and it was actually bison that maintained Indigenous ancestors’ ecologies, diets and cultural practices, but bison nearly went extinct because of settlers’ desire to turn the land into ranchland. While Bison isn’t as lucrative anymore, some Indigenous ranchers are utilizing their centuries-old rotational grazing methods with cattle, like Kelsey and Monte Scott with their company DX Beef.
Vermiculture and Vermiposting
Though vermiculture, involving the industry of the earthworm, is as old as time, vermicomposting is believed to be invented by Michigan biology teacher Mary Appelhof in 1972 as another way to use earthworms to help improve the quality of soil by making soil porous, which allows better aeration and quick absorption of water.
Vermiculture is the artificial cultivation of earthworms for their castings, which is an excellent biofertilizer and provides essential plant nutrients (nitrogen, potassium, phosphorous, calcium, and magnesium). It improves soil structure, by increasing soil’s water retention, improves soil aeration and helps hold in place nutrients that would leach away with water. Castings also feed soil microorganisms that store and slowly release plant nutrients to plants.
Vermicomposting, or worm composting, is the product of earthworm digestion and aerobic decomposition that takes food and other green waste then turns it into compost that is rich with nutrients and filled with microorganisms that maintain healthy soil.
It involves utilizing a bin to create a controlled system. It can be done in both rural and urban settings.
Healthy Soil and Our Health
Degraded soils affect human nutrition, and due to agricultural mismanagement over the last century the decline of soil fertility has affected the nutritional contents of fruits, vegetables and grains.
In a 2004 study, using USDA data, 43 garden crops were analyzed to make a comparison between the nutrition content of those in 1950 and 1999. While some nutrients were the same, several others like iron, phosphorus, vitamin C and calcium dropped by a range of 6 to 38 percent.
Dense microbial soil feeds nutrients to plants, which then deliver nutrition in our bodies after consumption. A 2020 report claims microorganisms in soil and food are interconnected with the human gut microbiome, which is also made up of trillions of microorganisms and lives in the intestinal tract.
These microorganisms are key to health and well-being, and play a key role in digestion, helping absorb nutrients, and are connected to one’s metabolism, body weight, immune regulation, brain functions and mood.
In the same way that microbial diversity in soil is decreased by agricultural chemicals, our microbial gut diversity is reduced by antibiotics. Both antibiotics and synthetic pesticides have been critically important societal interventions, Dr. Emeran Mayer told SALON, but the collateral damage to human and soil microbiomes has been “tremendous.”
Mayer is a gastroenterologist at UCLA’s Geffen School of Medicine, and author of the book The Gut-Immune Connection, which talks about the connections between the deterioration of our gut microbiome and the soil, and between our healthy and the health of the soil, the environment and the planet.
Mayer says that we must make critical changes to our food supply, including returning to sustainable practices that maintain the microbial diversity of the soil and that have less damaging effects on the climate.
In 2016 at COP22, the French Ministry of Agriculture called on nations to increase the carbon content in the top 40 centimeters of their soils by 4% per year. This initiative, called 4 per 1000 was said to be able to remove 3.5 gigatons of carbon from the atmosphere. Thirty-two nations signed on, including France, UK, Germany, Australia, as well as dozens of civil society and agricultural agencies.
Australia is one of a handful of countries with a soil health policy. A ten year strategy launched in 2021, it recognizes soil as a national asset worthy of sustainable management to benefit the environment, economy, food, infrastructure, health, biodiversity and communities.
In the United States, the 2018 US Farm Bill included important provisions to improve soil health, such as a pilot Soil Health and Income Protection Program and strategies to better use data to promote soil health.
Last year, USDA invested $10 million in a new initiative on their Conservation Reserve Program lands to sample, measure and monitor soil carbon to better quantify climate outcomes. Data collected will enable producers to evaluate potential carbon sequestration and greenhouse gas reduction.
Their Conservation Reserve Program is a voluntary program where in exchange for yearly rental payment, agricultural producers enrolled in the program agree to remove environmentally sensitive land from production and plant species that will improve environmental health and quality.
In early 2022, the US Department of Agriculture Natural Resources Conservation Service announced several new initiatives to support climate smart agriculture. Those programs are:
Farmers for Soil Health, which aims to advance use of soil health practices, particularly cover crops, on corn and soybean farms with the goal of doubling the number of corn and soybean acres using cover crops to 30 million acres by 2030.
The EQIP Cover Crop Initiative, which takes place in 11 states to help agriculture producers mitigate climate change through widespread adoption of cover crops. States include Arkansas, California, Colorado, Georgia, Iowa, Michigan, Mississippi, Ohio, Pennsylvania, South Carolina and South Dakota.
EQIP Conservation Incentive Contracts, which addresses priority resource concerns, including sequestering carbon and improving soil health in high-priority areas by working with producers on their operations using management practices, such as irrigation water management, drainage water management, feed management and residue and tillage management that target resource concerns, including degraded soil and water quality, available water and soil erosion.
Individual states like Hawai’i, Vermont, Utah, California and Oklahoma have also adopted legislation for initiatives for carbon sequestration and soil health.
Tribal Law and Policy
The Swinomish tribe in Washington contributed an amendment to the CDC’s framework for Building Resilience Against Climate Effects by emphasizing the importance of Indigenous health and soil as a priority resource, furthering policy goals that align with a “One Health” framework, where human health, animal health, and environmental health are all understood to be interconnected.
Many initiatives out there are also promoting “climate-smart” agriculture methods like carbon farming, which, according to the Carbon Cycle Institute involves management practices that are known to sequester carbon and/or reduce GHG emissions and gives opportunities for business partnerships that involve climate smart marketing for products, sustainable supply-chain creation, and other corporate sustainability initiatives.
These opportunities for business partnerships is what’s called the carbon market where corporate buyers like JPMorgan Chase, Shopify and North Face that are looking to counteract their greenhouse gas emissions can buy carbon credits off farmers who earn carbon credits by utilizing farm practices that sequester carbon, which is called a carbon offset, something that has been around for a few decades, but demand has grown due to increasing pressure to demonstrate a commitment to climate action.
In 2013, by utilizing California’s Air Resources Board Cap-and-Trade Program enabled the Yurok Tribe in Humboldt County to pay off loans from previous watershed purchases, support youth programming, housing, road improvement, as well as, buy back tens of thousands of acres of their traditional territory.
Outside of state programs, there are also private entities offering opportunities like Indigo Ag, who measures how much carbon can be sequestered, then gives registry-issued credits for the amount of emission reduction the farmer has contributed through their farm. This can then get traded to a bidder.
Indigo Ag, is a Boston-based startup with 1.2 billion dollars in funding. The firm sells carbon credits to companies, and farmers get 75% of the proceeds. After measurements are determined, the company also pre-pays farmers an amount verified by the Climate Action Reserve.
One of the company’s first clients, an Indiana farmer, claims to have made $52,000 in the first year – a pretty sizable revenue stream. However, the program might not compensate those who have already been adopting these practices for years.
Soil Health Organizations and Nonprofits
Global nonprofit whose mission is to safeguard and enhance the vitality and productivity of soils through scientific research and advancement, as well as, to empower farmers with the knowledge to successfully adopt regenerative soil health practices.
The Traditional Native American Farmers Association (TNAFA) holds an annual Indigenous Sustainable Food Systems Design Course (ISFSDC), providing training in ecological design, natural farming and earth restoration. ISFSDC is a holistic indigenous approach based on traditional knowledge and practices. These practices help improve air and water quality, ecosystems, nutrition and community health.
A farmer-led organization which uses local indigenous knowledge and agroecological methods to improve food security and nutrition in Malawi.
The Global Soil Biodiversity Initiative (GSBI) is a central forum that brings together scientists and policymakers to address the loss and maintenance of soil biodiversity, as well as, promotes international collaborations across a range of soil health topics, such as sustainable agriculture and curbing climate change.
The organization’s main objective is to improve soil health globally by addressing critical implementation, monitoring, policy, and public and private investment barriers that constrain farmers from adopting and scaling healthy soil practices.
Supporting BIPOC farmers to measure and monetize regenerative agricultural practices in the Southeastern US.
How You Can Create Healthy Soil at Home
Home gardeners can follow most of the same protocol as large farms, but to help encourage microorganisms to improve soil fertility and structure:
- Add compost to your garden. Here is a tip on how to compost.
- Plant cover crops.
- Keep your soil well-watered. High temperatures can kill microorganisms.
- Avoid physical disturbances so you don’t disrupt the soil structure.
- Mulch your beds. Mulching with organic matter like leaves or pine needles helps retain moisture in the soil while adding organic matter back into the soil.
- Avoid pesticides to not kill off the microorganisms.