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Diversified No-Till Crop Rotations: Soil Health Attributes across Multiple Ecozones on the Canadian Prairies
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- Author / Creator
- Iheshiulo, Ekene M.-A
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Traditional cereal-based cropping systems on the Canadian prairies have contributed considerably to soil and environmental degradation, increased production costs, and a threat to agricultural sustainability. To address global food demand, there is a need for sustainable cropping systems that enhance soil health (SH) in current climate conditions while reducing the use of agrochemicals. This dissertation focuses on understanding the impact of diverse crop rotations on SH. Chapter 2 presents a meta-analysis, which revealed that increased crop diversity significantly reduces bulk density, enhances soil aggregation, improves total porosity, and saturated hydraulic conductivity. Although it did not significantly change the infiltration rate, the benefits were more pronounced in medium- and fine-textured soils with >900 mm mean annual precipitation, especially when managed with conservation practices for 5 to 10 years. Chapters 3 and 4 document a multi-year field study conducted at three Canadian prairie sites (Lethbridge, Swift Current, and Scott). Six 4-year crop rotations [denoted as conventional (control), pulse/oilseed intensified, diversified, market-driven, high-risk and high-reward, and soil health-enhanced rotations] were established under no-till in 2018. Chapter 3 explores short-term soil organic matter (SOM) and aggregate stability (AS) dynamics, showing no improvement in SOM fractions but significant changes in AS at two sites (Lethbridge and Swift Current), with the soil health-enhanced and high-risk and high-reward rotations having the highest AS. Chapter 4 investigates how diverse crop rotations can alter soil hydraulic and physical quality, demonstrating moderate improvements in rotations with legumes and increased functional diversity, depending on the site. Chapter 5 assesses overall SH using a minimum dataset, revealing that the diversified rotation at Lethbridge and Swift Current, along with the high-risk and high-reward rotation at Scott exhibited the highest SH index. However, the number of indicators varies across sites, with common indicators such as soil organic carbon, bulk density, macroporosity, and plant-available water capacity. In conclusion, increasing the crop and functional diversity in rotations has the potential to sustain SH and contribute to sustainable agroecosystems but may require a longer period to become more evident.
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- Graduation date
- Fall 2024
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.