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18 POTATO GROWER | AUGUST 2020 Why all the discussion about soil health? Picture of Health Diggin' In Diggin' In SOILS | By Linda Schott & Mike Thornton It seems like you can't open a magazine or webpage without reading something about soil health. What exactly is soil health, and what work is being done to understand soil health in cropping systems? According to the Food and Agriculture Organization (FAO) of the United Nations, soil health is defined as the continued capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain biological productivity, promote the quality of air and water environments, and maintain plant, animal and human health. For cropland, this definition can be interpreted as the continued capacity of soil to function as a vital living system to sustain healthy crop production. One proven way to improve soil health is to increase soil carbon and soil organic matter. The reason no-tillage practices and cover crops increase soil health is by reducing carbon loss or increasing carbon capture through photosynthesis, respectively. The five tenets of soil health are: 1. Less soil disturbance; 2. Diversify soil biology with plant diversity; 3. Keep a living root growing throughout the year; 4. Keep soil covered as much as possible; and 5. Incorporate grazing. Soil has inherent and dynamic properties. Inherent properties, such as soil texture, surrounding landscape and depth to bedrock do not change easily; these characteristics took millennia to form. Dynamic properties, on the other hand, are affected by management and can change within months or a few years. Dynamic properties include characteristics like organic matter, soil structure and water- and nutrient-holding capacity. The ultimate goal of soil health is to manage the soil so that it is not degraded for future use by maintaining and even increasing the soil's ability to perform its basic functions. These functions include regulating water, sustaining plant and animal life, filtering and buffering potential pollutants, cycling and storing nutrients, and providing physical support for things like human structures and plant roots. Soil biology is recognized as an important contributor to overall soil health and makes up part of the "living ecosystem" part of the definition. Fauna inhabiting soil affect and are related to many physical and chemical characteristics critical to crop production. Soil bacteria and fungi form the base of the soil ecosystem. These organisms both create soil organic matter and are part of soil organic matter. Thus, they are a critical component of healthy soil. Soil bacteria and fungi consume organic matter, as well as animal and plant residues (i.e., manure, compost and crop stubble), which helps to cycle nutrients in soil. The bottom line is that if soil is not healthy, crop production becomes increasingly more difficult and expensive. For example, if soil microbial populations are severely decreased (through tillage, fumigation, etc.), fewer nutrients are cycled. This means that more inorganic fertilizer should be applied and there is a higher risk for nutrient loss to the environment. Without organic matter and soil carbon, soil structure becomes a limitation due to surface crusting and compaction. Fortunately, these issues can be addressed by incorporating some (or all) of the five tenets of soil health. Healthy soil is built over time and changes to management practices can (and should) be incremental. After all, Rome wasn't built in a day! Potato and Soil Health Projects in Idaho MAGIC VALLEY SOIL HEALTH PROJECT The general belief in southern Idaho is that the "soil health movement" has been slow to take hold. Consequently,