Land Use Effects On Soil Biological Properties In Two Topographically Variable Agroecosystems In Saskatchewan
Soil biological properties tend to be under utilized as indicators in soil health tests. Novel measures - those seldom used in such metrics - such as microbial abundance and biomass, community structure, and enzyme activity are directly related to soil resource availability, organic matter decomposition, and nutrient cycling, which are affected by agricultural land use. The inclusion of biological properties in soil health tests may allow land managers to compare the effects of management practices faster than if they relied solely upon changes in chemical and physical properties over time. The objective of this project was to measure how enzyme activity, microbial abundance, and community structure are affected by annual and perennial cropping systems at different landscape positions, over different depths, and across the growing season at two different locations within the province, [St. Denis National Wildlife Area (SDNWA), and the Conservation Learning Centre (CLC)]. The SDNWA and CLC were chosen due to their topographic variation and presence of adjacent perennial and annual land use. Samples were taken at different landscape positions at different time points within the growing season to account for both location and seasonal effects on soil function. Time within the growing season influenced enzyme activity differently between perennial vs. annual cropping systems at both sites. However, seasonal dynamics in the annual system differed between the two sites due to differences in crop rotation. For example, SDNWA had elevated enzyme activity in the annual cropping system early in the growing season, a trend that did not exist at CLC. The effects of perennial cover were found to often buffer the effects of topography in the perennial agroecosystems, which affected not only enzyme activity but also PLFA abundance, particularly fungal signatures. Finally land use effects were moderated by both topographic and depth effects at CLC in a complex interaction which affected enzyme activity and PLFA abundance, while the same interaction was not seen at SDNWA. These findings indicate that novel soil biological properties respond to changes in management factors often interconnectedly with land use, and environmental factors such as topography, depth, and season, and that these biological properties could be valuable additions to soil health indices.
Soil Health, Soil Health Indicators, Soil Health Indices, Biological Properties, Soil Enzymes, Enzyme Activity, PLFA, Soil Community, Community Abundance, Seasonality, Topography, Slope Position, Depth, Variability, Land Use
Master of Science (M.Sc.)