Soil health refers to how well the soil can support life and natural processes in its environment. In simpler terms, healthy soil comes from the good working together of all parts of the soil, including living things like microorganisms, plants, and animals, as well as non-living parts like minerals and water. A soil might be healthy in terms of helping ecosystems function properly, but it may not always directly help grow crops or provide nutrients for humans. Scientists are still discussing the best ways to measure and define soil health.

Testing soil health helps assess its condition, but these tests are often focused on helping farmers grow crops. Healthy soil depends on the variety of living things in it, especially strong populations of microorganisms. Soil health can be improved through careful management, such as keeping plants or cover crops on the soil to protect it and adding natural materials that contain carbon, like compost or manure. Inorganic fertilizers, which are made from non-living materials, do not always harm soil health if used in proper amounts. When used correctly, they can help plants grow better, leading to more organic material being added to the soil over time.

Aspects

The term "soil health" describes the condition of soil based on several important factors:

• Helping plants and animals grow well (agronomic focus);
• Supporting a wide variety of living things in the soil (ecological focus);
• Keeping water and air clean (environmental/climate focus);
• Contributing to human health and living conditions;
• Storing carbon.

The phrase "soil health" has mostly replaced the older term "soil quality." The main difference is that "soil quality" focused on how well soil could perform a specific task, such as growing corn or building roads. The word "health" changed the way people think about soil, emphasizing a complete and balanced view of soil as a self-sustaining system. These two terms still share many similarities. The idea of "soil health" began with organic farming groups in Europe, even before "soil quality" became a formal topic in the 1990s. In 1978, Swiss soil scientist Dr. Otto Buess wrote an essay titled "The Health of Soil and Plants," which helped define the field of soil health today.

The key idea behind "soil health" is that soil is not just a lifeless material for plants to grow in, as modern farming often suggests. Instead, soil is a living, changing environment. Soils that are very productive for growing crops are also rich in life. Scientists now know that soil contains a large number of tiny living organisms. In temperate grassland soil, bacteria and fungi can weigh up to 1–2 tons and 2–5 tons per hectare, respectively. Some scientists believe that microbes control about 80% of soil's ability to provide nutrients.

Using the example of human health, a healthy soil can be described as:

• In good condition in terms of its biological, chemical, and physical properties;
• Not sick or damaged, and not causing harm to other areas;
• Having all its features work together so the soil can reach its full potential and avoid damage;
• Performing all its important functions, such as moving nutrients, carbon, and water, in a way that keeps these abilities strong for the future.

Conceptualisation

Soil health describes how well soil is working in a specific area, compared to certain standards that show what healthy soil should do. It is not correct to talk about soil health when preparing soil for roads, as this is more like comparing soil quality to a different kind of use. People may define soil health in different ways because they might care more about certain soil functions, like growing plants or holding water. Because of this, the meaning of soil health depends on who is using the term, what they want the soil to do, and how they define the area being studied. Important parts of the discussion about soil health include differences in ideas, such as protecting natural landscapes versus helping crops grow, each of which has its own way of measuring soil health.

Interpretation

Soil health standards vary based on the natural traits of the soil and its location. Healthy soil is defined by these general features:

• Soil can support many types of plants and crops.
• Many different living things, like plants, animals, and microbes, live in the soil.
• Soil can hold and use water and nutrients well, based on the climate where it is found.
• Water flows off the soil in a way that doesn't cause problems.
• The soil is stable and doesn't break down easily.
• The soil doesn't lose its important parts, like minerals or organic matter.

• There is plenty of plant life covering the soil.
• Carbon levels are close to what is normal for that type of soil and climate.
• Nutrients don't leave the soil easily.
• The soil supports plant and crop growth as much as it should, based on its environment and climate.
• Soil erosion happens very slowly, like it does naturally over time.
• Toxins or harmful substances don't build up in the soil.

Unhealthy soil is the opposite of these conditions.

Measurement

Soil health will be measured by comparing the services provided by individual ecosystems to a standard. Specific standards used to evaluate soil health include the amount of carbon dioxide released, levels of humus, activity of microorganisms, and the availability of calcium.

Soil health testing is becoming more common in the United States, Australia, and South Africa. Cornell University, a land-grant college in New York State, has offered a Soil Health Test since 2006. Woods End Laboratories, a private soil lab started in Maine in 1975, has provided a soil quality package since 1985. Both services combine physical tests (such as aggregate stability), chemical tests (such as mineral balance), and biological tests (such as carbon dioxide respiration), which are now considered important features of soil health testing. Other soil labs entering this field often add biological factors to standard chemical nutrient testing. One example is testing biological soil respiration, known as "CO2-Burst," which has been adopted by commercial labs since 2006.

However, some soil testing labs and university scientists are hesitant to include new biological tests. This is because traditional soil fertility measurements are based on models from "crop response" studies, which link crop yields to specific chemical nutrient levels. No similar models exist for soil health tests. Critics of new soil health tests argue that these tests may not detect changes caused by different farming practices.

Soil testing methods have changed slowly over the past 40 years. During this time, U.S. soils have lost up to 75% of their carbon (humus), which has reduced biological fertility and ecosystem functions. The extent of this decline is debated. Many critics of traditional testing methods say the loss of soil quality shows that older models are no longer effective and must be replaced. These older models focused heavily on maximizing crop yields and calibrating yields to nutrient levels, leading to the neglect of other factors. As a result, pollution of surface and groundwater with excess nutrients, such as nitrates and phosphates, has increased significantly. Reports from the early 2000s in the United States showed the worst levels of pollution since the 1970s, before environmental awareness grew.

Regenerative Agriculture & Soil Health

Regenerative agriculture is a farming method that focuses on protecting soil, increasing plant variety, and managing land in a way that lasts over time. It uses practices that improve soil health, such as adding organic matter and reducing harm to the environment. This approach combines knowledge from local and indigenous communities with scientific research to create farming systems that help people and the environment. A key idea in regenerative agriculture is that healthy soil is essential for growing food, so the focus is on nurturing the soil rather than only feeding plants.

Regenerative agriculture helps crops grow in a way that is better for the environment. Studies show that these methods improve how nutrients move through the soil and support a wide range of plants and animals. Practices like planting cover crops, rotating crops, avoiding tilling the soil, using natural pest control, and composting help build strong, self-sustaining soil ecosystems. These methods reduce the need for chemical fertilizers and pesticides. For example, cover crops protect the soil during winter, stop erosion, and help nutrients move through the soil. Rotating crops adds different nutrients to the soil and reduces the need for chemicals. No-till farming keeps the soil structure intact, improves water absorption, and keeps carbon in the ground instead of releasing it into the air.

Permaculture, a design method used in regenerative agriculture, helps create farming systems that copy natural ecosystems. It uses techniques like planting companion crops, adding mulch, and growing long-lasting plants to improve soil health and use resources efficiently. These practices help prevent soil erosion, increase soil fertility, and support the tiny living things in the soil that help plants grow.

Regenerative agriculture also benefits farmers and their communities. It lowers costs by reducing the need for expensive chemicals, which can increase profits. Healthier soil from practices like cover cropping and composting leads to better crop quality and higher yields. However, these methods often require more manual labor because they rely less on heavy machinery. Additionally, regenerative agriculture helps communities by providing fresh, local food and reducing hunger. Programs like Community Supported Agriculture (CSA) connect farmers directly with consumers, strengthening relationships and supporting local economies.

Regenerative agriculture helps fight climate change by storing carbon in the soil through methods like composting and no-till farming. These practices reduce carbon dioxide in the air while improving soil health and productivity. Adding organic materials to the soil increases the amount of carbon stored in the ground, which helps the soil work better and grow more food.

Together, these practices create strong soil ecosystems that help plants grow, protect against pests and diseases, and store carbon to reduce greenhouse gases. However, challenges remain in measuring the success of regenerative agriculture. Some important signs of soil health, like the activity of tiny living things, are hard to assess because they depend on specific knowledge and are not always measured the same way. More research is needed to fully understand the benefits of regenerative agriculture and to help it be used more widely.

Soil health gap

Soil is essential for global food security, agricultural ecosystems, the environment, and human life. This has led to a rapid increase in research focused on soil health. However, the absence of benchmarks specific to certain areas or regions has made it difficult to study how different farming practices affect soil health. In 2020, Maharjan and his team introduced a new term called "Soil Health Gap." They explained that the natural land in a specific region can serve as a reference point to compare the effectiveness of various management practices. This approach also helps measure the differences in soil health conditions across areas.