Keunbae Kim | ALES Graduate Seminar

Date(s) - 15/10/2021
9:30 am - 10:30 am

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.

This is an ALES MSc Final Exam Seminar by Keunbae Kim. This seminar is open to the general public to attend.

Join Zoom Meeting:

Thesis Topic:

Soil Carbon Relationship in Agroecosystems:  Mycorrhizae, Methane Flux and Organic Matter Dynamics.

MSc with Drs. Guillermo Hernandez Ramirez and Monika Gorzelak.

Seminar Abstract:

Perennial grain crops have been proposed as a sustainable alternative to conventional annual grain crops, since they potentially hold multiple desirable features: increase of soil C sequestration and biodiversity, mitigation of greenhouse gases, and reduction of water loss, etc. These attributes can be accomplished by their no-tillage management, longer growing season, and pervasive root systems. Nonetheless, the ramifications of novel perennial grain cropping systems in the atmosphere, lithosphere, and biosphere remains elusive. In this research, comprehensive assessments have been implemented to enhance current understanding of the contrasting cropping systems (i.e., annual vs perennial grain cropping) by investigation of soil organic carbon pool, GHGs emissions, and mycorrhizae. The experimental design was established by five contrasting cropping systems [fallow, spring-grain, fall-grain, perennial-grain, and perennial-forage] both with and without N fertilizer additions. A randomized complete block design (RCBD) consisting of four replicates was initiated at two sites located in Edmonton and Breton, Alberta, Canada. In addition to replicates plots, two adjacent 4-ha fields, including annual vs. perennial grain crops, were set up for eddy covariance systems measurements at the Breton site. As a result, perennial grain crops contributed to increase C concentration in the either transitory or stable pools, although overall soil C sequestration occurred as a function of N fertilizer, cropping systems options, and underlying soil texture. Moreover, substantial CH4 and CO2 uptake were observed in perennial grain cropping system compared with annual grain crops. It is likely due to that mediating mechanisms by perennial grain cropping systems shift to favorable GHGs sink conditions such as aeration-moisture balance, photosynthetic activity, and microbial decomposition. However, overall cumulative ET and associated ecosystems-water use efficiency (WUEe) were similar with between two crops. Lastly, AMF community compositions between annual and perennial grain cropping systems exhibited no significant difference, likely due to the genetic similarity of two crops. In addition, the two contrasting study sites had different patterns of AMF alpha and beta diversity, which may be a result of differing inherent soil properties and management legacy effect across field sites. In sum, AMF communities appear to be impervious to annual vs perennial grain crops, rather their most pronounced difference are field site specific.