Plant-Soil Feedback and Perennial Forage Systems

Plant-soil feedback (PSF) is the process by which plants influence the survival and growth of other plants through effects on the soil and its biota. Understanding how PSF and management practices interact to influence native species persistence is critical for sustainable perennial forage systems. I combined a multi-year field trial with a controlled greenhouse PSF experiment to evaluate how harvest frequency and community composition influence native species performance and soil microbiome composition. Field plots, including monocultures and mixtures of seven forage species, were harvested once or twice annually. Soils from these plots were used to inoculate the focal forage species and assess their PSF responses under controlled conditions. Field results showed that non-native species, especially Medicago sativa, suppressed native cover, while native grasses (Elymus lanceolatus, Pascopyrum smithii) were more persistent than the native legume Astragalus canadensis. Harvest frequency altered these trends: twice-per-year harvests reduced non-native dominance and benefited A. canadensis, while single harvests favored grasses but accelerated A. canadensis decline. In the greenhouse, PSF responses were species-specific: all grasses showed consistent negative PSF, while the native legume A. canadensis displayed positive PSF in mixture but negative in monoculture conditioned soils. In contrast, the non-native legumes M. sativa and Onobrychis viciifolia displayed neutral to negative PSF across both soil types. Plant-soil feedback effects were independent of soil origin, suggesting a strong role of generalist microbes, potentially due to homogenization of soil biota via shared land-use history. These findings underscore the importance of species identity, competition, and management in mediating above- and belowground dynamics. Optimizing forage mixtures requires balancing species selection with disturbance regimes to leverage PSF benefits while mitigating competitive exclusion.

Name thesis:degree_name

Master of Science (M.Sc.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Plant Sciences

Grantor

University of Saskatchewan

Year dc:date.issued

2026

Author dc:creator

• Huang, Yun

Committee members dc:contributor.committeemember

• Bennett, Jonathan
• Helgason, Bobbi
• Congreves, Kate
• de Oliveira Scarpino van Cleef, Flavia

• Plant-soil feedback
• perennial forage systems

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10388/18108

OAI identifier oai:identifier

oai:harvest.usask.ca:10388/18108