Relationships between field management, soil health, and microbial community composition
Citation
Mann, C., Lynch, D., Fillmore, S., Mills, A. (2019). Relationships between field management, soil health, and microbial community composition. Applied Soil Ecology, [online] 144 12-21. http://dx.doi.org/10.1016/j.apsoil.2019.06.012
Plain language summary
More meaningful and useful soil health tests are needed to enable better on-farm soil management. Our objective was to look at the relationship between field management and soil health when compared to a scientific analysis called phospholipid fatty acid profiling (PLFA). Using PLFAs, researchers can measure the abundance of different biomarkers from organisms that are active in the soil. These biomarkers give an idea of whether or not the soil agroecosystem is stable or under stress. The approach of this study was to interview (anonymously) each of 34 participating farms of all types and take samples from the best field on their farm and the worst field on their farm. The soil samples were subjected to the “Cornell Soil Health Assessment (CSHA)”, conventional soil nutrient analysis at a regional lab, and PLFA done in our lab at AAFC in Charlottetown. Interviews were conducted to record farmer management decisions were correlated with a field being considered “good” or “poor” by the farmer. We then checked to see if CSHA, PLFA or conventional soil nutrient analysis would be able to show differences between “good” and “poor” fields. Soil nutrient analysis was the only technique that was able to show differences between “good” and “poor” farmer’s fields. Both CSHA and PLFA were associated with the biological component of the soils, but did not show a difference between “good” and “poor” fields. The study shows that no single approach can give a clear answer, but that a combination of all techniques need to be evaluated on a region-by-region basis.
Abstract
More meaningful and useful soil health tests are needed to enable better on-farm soil management. Our objective was to assess the relationship between field management, soil health, and soil microbial abundance and composition (phospholipid fatty acid analysis (PLFA)) in soil collected from two fields (farmer-designated ‘good’ versus ‘poor’) across 34 diverse (livestock, grain or vegetable cropping) farms in Maritime Canada. Soil health was measured using soil texture, surface hardness, available water capacity, water stable aggregates, organic matter, soil protein, soil respiration, active carbon, and standard nutrient analysis. All soils were medium to coarse textured (<8% clay). Mixed models analysis showed that both CSHA and PLFA were able to resolve statistical differences between cropping systems, however conventional soil chemical analysis was the only testing method to resolve statistical differences between farmer designated ‘good’ and ‘poor’ fields. Principle component analyses determined management history (rotation over previous three years), but not ‘good’ or ‘poor’ field designation, to be an important determinant of soil health. Water-stable aggregates and soil respiration were positively correlated with all PLFA microbial groups, and negatively correlated with sand, P, Cu and Al. Lower-intensity management (perennial forage, mixed annual-perennial cropping), manure application and low tillage were linked to higher soil respiration, water-stable aggregates, fungi, mycorrhizae, Gram negative bacteria, and lower soil available P. Correlations between CSHA and PLFA shows promise for integrating these two tests for improved soil health assessment.