Impacts of Short-Term Cover Cropping on Soil Microbial Communities and Biogeochemical Functions in Prairie Canada
Date
2023-09-20
Authors
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Thesis
Degree Level
Masters
Abstract
Cover crops have the potential to confer numerous benefits to agricultural soils. Many ecosystem services derived from cover crops are underpinned by activities of soil microorganisms, while the cover crop acts as a catalyst. While the biological impacts of cover crops are relatively well understood in temperate agroecosystems, research in semi-arid environments is limited. My research addressed this knowledge gap by focusing on the impacts of cover cropping on biological indicators of soil health in semi-arid agroecosystems. I analyzed phospholipid fatty acid (PLFA) abundance and composition, and extracellular enzyme activity (EEA) in soils at three locations in the Canadian prairies: Saskatoon, Saskatchewan; and Carman and Glenlea, Manitoba. The study had eleven treatments at each site, comprising four-year rotations with and without cover crops, two-year rotations without cover crops, and a perennial alfalfa check, arranged in a randomized complete block design with four replicates per site. Cover crops were first grown in Saskatoon and Carman in 2018, and in 2019 in Glenlea. Surface soils were sampled in fall 2020, spring 2021, and summer 2021. I hypothesized that cover cropping would support a more active, abundant soil microbial community and impose changes in microbial community composition, leading to improved soil health compared to non-cover cropped treatments. The perennial alfalfa had higher fungal PLFA abundance and lower stress indicators compared to rotation treatments. Sampling time affected total PLFA abundance (p < 0.05) at all locations, and EEA measurements at nearly all sampling times and locations. However, specific impacts of seasonality differed between sites. The inclusion of cover crops did not affect PLFA abundance, microbial community composition, nor EEA activity. These findings suggest that biological indicators of soil health in the short-term are more impacted by factors aside from cover cropping, such as soil properties or climatic differences, and do not support the use of cover crops to enhance biological soil health in the short-term. These results may be partly due to the limited time cover crops had to establish sufficient biomass to induce effects on soil microbial communities. Longer-term studies may use these findings as a benchmark and should track changes attributable to cover cropping over a longer timeframe.
Description
Keywords
soil, cover crops, soil health, soil microbiology, PLFA, soil enzymes, cover cropping
Citation
Degree
Master of Science (M.Sc.)
Department
Soil Science
Program
Soil Science