Enhancing the Saskatchewan Soil Health Assessment Protocol – Phase 2
Term: 4 years ending April 2024
Status: Complete
Researcher(s): Kate Congreves, Rich Farrell, Melissa Arcand, Athena Wu, U of S
SaskCanola Investment: $143,558
Total Project Cost: $287,116
Funding Partners: SWDC
Grower Benefits
Healthy soils form the basis of productive farming systems, and soil health tests can be useful tools to support good management decisions. The concept of soil health recognizes soil as a living and dynamic natural system, a notion that aptly fits in the realm of biology; however, soil health tests are often dominated by indicators of soil fertility and chemistry. Biological indicators of soil health remain understudied and underrepresented in soil health assessments.
To address this gap, we evaluated biological indicators of soil health (including organic and total C, total N, mineralized C, extracellular enzyme activity, and phospholipid fatty acid (PLFA) analysis for microbial biomass and adaptation response ratio (ARR)). To do so, 153 soil samples were collected from different fields producing major field crops (cereal, oilseed, pulses), spanning the Black, Dark Brown, and Brown soil zones in Saskatchewan. We assessed whether soil biological indicators could be contextualized by soil classification and measured their responsiveness to different agricultural management practices. Despite the dynamic nature of biological indicators of soil health, we found that soil classification by great group constrained measurements and served as a useful contextualizing factor to adjust scoring functions. Further, we found biological indicators of soil health (namely soil organic C, total N, and P and S enzyme activity) generally improved with more regenerative crop production practices such as cover cropping or organic management. Although other indicators such as CO2 mineralization, N and C cycling enzymes, PLFA and ARR showed fewer differences among crop production practices, all were greater under prairie grassland than cropland soils. These trends were also supported by soil organic matter stoichiometry (N:C, P:C, and S:C) results, suggesting that element to carbon ratios might be useful features for future soil health assessments. As a result of this project, a soil health scoring tool was developed where users can input a soil test result for key biological indicators (i.e., soil organic C, total N, CO2 mineralization, and PLFA microbial biomass), select their soil zone, and then be provided with the resultant soil health ranking and description of the relative soil health status for their sample. This tool will be available on my lab website. We will continue to build on the tool as part of the Saskatchewan Assessment of Soil Health (SASH) framework.
Final Report PDF: Enhancing the Saskatchewan Soil Health Assessment Protocol – Phase 2