By Dunling Wang, PhD, PAg, Provincial Specialist, Alternative Cropping Systems, Regina
The term soil health is in very common use these days. It has been used interchangeably with soil quality and soil fertility, which often causes confusion.
Soil health can be defined as the capacity of a soil to function as a biologically balanced dynamic system that sustains plants, animals and humans. It refers to a self-regulated, stable and resilient ecosystem. In contrast, soil quality refers to how well a soil performs its functions to provide nutrients and water to plants, filtering and cleaning water, regulating temperature, recycling and storing nutrients, and providing habitats for organisms. Soil fertility, meanwhile, is directly related to the nutrient level available to crop growth, such as available nitrogen (N), phosphorus (P), potassium (K), sulfur (S) and other micronutrient contents. Another term often being used is soil productivity, which actually implies the soil's ability to produce crops. Soil productivity can be high by carefully using additional nutrients and irrigation, even if soil fertility is low.
Soil health can be built by following the principles of regenerative agriculture, including reduced-till to decrease soil erosion, growing cover crops to increase soil organic matter, and applying fertilizers and manure to improve soil fertility. Products like animal manure and vegetative composts that contain high level of N, P, S and other micronutrients can help crop growth, increase soil organic matter and improve microbial population and varieties and eventually improve soil health. Dr. Diane Knight, a professor from the Department of Soil Science at the University of Saskatchewan, experimented with various soil amendments and found that manure-based products are effective in producing better crops and improve soil health, while adding arbuscular mycorrhizal fungi (AMF) inoculants does not increase crop nutrient uptake nor increase AMF population in the soil.
It is important to continuously invest in improving your soil health in order to increase crop yields and maintain a sustainable operation. Some producers choose to do this by growing cover crops or adding livestock to their operation; others apply manures and use soil amendments.
In recent years, several "soil health regenerator" have come into the market. The manufacturers state that the products are made from natural compounds or contain soil health-regenerating microbes. They claim that by applying a small amount, the soil health can be quickly rebuilt. In reality, these products may contain small amount of organic materials, plant nutrients and some foreign soil microbes. The effectiveness of these products remains largely unknown, and further scientific research and field testing is required to verify their claims.
At present, the best ways to build soil health are using management practices that reduce disturbing the soil, adopting diversified crop rotations, growing cover crops and covering the soil with crop residues. These management practices have documented long-lasting effects on reducing erosion of surface soils, returning organic matter and plant nutrients to soils, and promoting indigenous organisms to thrive in the soils. Adding manure is also an effective way to improve soil fertility. However, when you are considering investing in soil amendments, do a product investigation, ask many questions, and consult with someone who has previously used the products or conduct strip tests on your own farm to compare it with a proven product before making a significant investment for large acres.