Soil health is defined as the continued ability of soil to function as a vital living ecosystem, allowing for sustainability of plants and animals, including humans. The primary factors that promote a healthy soil are to maximize living roots, soil cover and biodiversity while minimizing soil disturbance. Healthy soils can sustain both plant and animal life providing soil biodiversity, maintain or enhance water and air quality, and support humans and wildlife. The underlining principle for a healthy soil is to act as a medium to grow plants and to create a living, dynamic and ever-changing environment that is influenced by human activities.

Soil – What is it?

The soil is a mixture of particles from minerals, organic matter, water, and air. It contains both living micro- and macro-organisms that provide support to other animal and plant life. Soil acts a reservoir for water and nutrients for plant, and animal life. Soil organic matter is derived from plants and animals, and their by-products. While organic matter only makes up a small portion of soil, it serves an essential role in maintaining soil health. As organic matter breaks down, it is converted into pools that serve as sources of plant nutrients eventually breaking down to humus.

Impact of conventional agriculture on soil health

In row crop monoculture production, soil health can be negatively impacted by tillage practices and chemical applications. However, soil conservation practices such as no-till production systems, longer crop rotations, and cover crops can help restore soil health. Restoration of soil health over time with these practices can result in increased water infiltration, organic matter, water storage, and soil structure. Extended crop rotations that include small grains, legumes and/or cover crops will increase soil microbial biodiversity, guard the soil surface, and provide organic carbon return to the soil.

Assessing soil health

Soil health cannot be determined by directly measuring crop yields or other factors, it is measured by various indictors of soil health. (Table 1.) The indicators can be physical, chemical, and/or biological properties/processes or the characteristics of soils. When assessing soil health, the following supplies are helpful: Shovel; wire flags, penetrometer or tile probe, clear plastic containers, wire sieve, water, phone camera, and small hand lens. A soil type by feel guide is also recommended.

Components of healthy soil:

• Soil organic matter percentage. A higher level indicates increase in nutrient retention and soil fertility, improved soil structure and soil stability, and less soil erosion.
• Physical characteristics such as bulk density, water infiltration rate, soil structure and macropores, and water holding capacity.
• Chemical characteristics such as electrical conductivity, reactive carbon level, soil nitrate, soil pH, and extractable phosphorus and potassium levels.
• Biological components such as earthworms (Figure 1), microbial biomass of Carbon and Nitrogen, particulate organic matter, potentially mineralizable N, soil enzymes, soil respiration, and organic carbon level.

Figure 1. Earthworms are a good basic indicator of soil health. They eat plant material at the soil’s surface. Its cast-off wastes and debris are mixed at the soil’s surface with fresh plant material to form a small mound at the entrance of its burrow. The mound is called a midden (left). Once surface residue is removed, a small, burrowed channel can be seen (right).

Soil is a critical resource—the way in which it is managed can improve or degrade the quality of that resource. Soil is a complex ecosystem where living microorganisms and plant roots bind mineral particles and organic matter together into a dynamic structure that regulates water, air, and nutrients. A healthy soil provides many functions that support plant growth, including nutrient cycling, biological control of plant pests, and regulation of water and air supply. These functions are influenced by the interrelated physical, chemical, and biological properties of soil, many of which are sensitive to soil management practices. Because soil health changes slowly over time, management practices take variable amounts of time for desired effects to be observed and measured.

Soil Health Worksheet

Click here to access this article as a printable soil health worksheet. This will help you go through each condition, assess variables and work to obtain the ultimate soil health target.

Sources

Soil assessment. USDA-NRCS.

Al-Kaisi, M. 2014. What is soil health and how can we improve it? Iowa State University Extension. https://crops.extension.iastate.edu/cropnews/2014/02/what-soil-health-and-how-can-we-improve-it White, C. and Barbercheck, M. 2017. Managing soil health: concepts and practices. Pennsylvania State University Extension. https://extension.psu.edu/managing-soil-health-concepts-and-practices

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