Effect of Biochar on Soil Microbial Communities, Nutrient Availability, and Greenhouse Gases in Short Rotation Coppice Systems of Central Alberta

  • Author / Creator
    Taghavimehr, Jamal
  • Short rotation coppice (SRC) systems using willow (Salix spp.) grown on marginal soil, amended with biochar may represent a promising source of renewable green energy for rural communities of Alberta. The Ohaton Wood Energy project, an agroforestry site located in Camrose County, is one of several ongoing SRC projects in Alberta. This project evaluated the effect of biochar on microbial communities, nutrient availability, and greenhouse gases (GHG) in Solonetzic soils dedicated to agroforestry purposes. The study used both lab incubation and field plots to examine the effect of biochar. In the lab incubation, straw and willow biochars were applied to low and high EC soils. The application rates of biochar were 0, 1, 2.5, 5, and 10% (w/w). Chloroform fumigation extraction and alkali trap methods were used to assess soil microbial biomass and activity. Microbial biomass carbon (MBC) and nitrogen (MBN) increased in the presence of biochar in low EC soil. In high EC soil, the metabolic quotient increased, while MBC was reduced. Nitrate (NO3-) availability was reduced with biochar addition. In the field study, willow and conifer biochars were applied at 1 and 2.5% (w/w) application rates, to high and low EC and waste water irrigated and non-irrigated zones. The metabolic quotient increased by 177% with addition of conifer biochar at 2.5% rate in irrigated soil. MBC and MBN didn’t change drastically in response to biochar additions. Phospholipid fatty-acid (PLFA) analysis and community level physiological profiling (CLPP) were used to examine soil microbial structure and function. Non-metric multidimensional scaling (NMS) was used to distinguish differences between these microbial profiles. Biochar didn’t alter PLFA structure in any of treated soils compared to control, but conifer 2.5% changed CLPP in both high and low EC soils. These results indicate that microbial function can change in a short period of time with addition of biochar, but microbial structure and biomass may need more time to shift. Plant root simulator probes were applied in-situ to measure soil nutrient bioavailability. NMS was also applied to compare nutrient profiles. The nutrient profiles of conifer 2.5% and willow 1% were significantly different from the control in non-irrigated high EC zone. Photoacoustic multi-gas analyzer was connected to static chambers to measure CO2 and N2O emissions from soil. Biochar decreased gas emissions from non-irrigated high EC plots in the first 3 weeks. Establishing a strong link between GHG emissions, soil microbial processes, and nutrient profiles as indicators of ecosystem functions needs further research.

  • Subjects / Keywords
  • Graduation date
    Fall 2015
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries 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.