PARENT SESSION
Poster Session 23: Soil Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Microbial activity in a hybrid poplar plantation as influenced by fertilization.
Lteif, Arlette*,1, Whalen, Joann1, Camire, Claude2, Bradley, Robert3, 1 Mcgill University, Montreal, Quebec, Canada2 Université Laval, Laval, Quebec, Canada3 Université de Sherbrooke, Sherbrooke, Quebec, Canada
ABSTRACT- Soil microorganisms are key regulators of decomposition and nutrient cycling, which are linked to net primary production (NPP) in forest ecosystems. An increasing percentage of the trees used for pulp and paper production are harvested from afforested agricultural land. Fast-growing tree species such as hybrid poplars are preferred, and fertilizers are often applied to maximize the annual NPP. Soil microbial activity is expected to be different when organic or inorganic fertilizers are applied. The objectives of this study were 1) to determine how soil microbial activity was affected by the fertilizer source applied to a hybrid poplar plantation, and 2) to determine whether the NPP of hybrid poplars was influenced by the fertilizer source. The field site in St-Camille, Québec, Canada was a plantation of Populus trichocarpa x Populus deltoides , on an abandoned hayfield. Treatments included an unfertilized control, inorganic fertilizer, and four organic fertilizer treatments (papermill biosolids and pig slurry, applied alone or in combination). Fertilizers were applied at 35 and 70 kg N ha-1 to replicated plots in May 2004, and soil samples were collected in June and September 2004. Soil microbial biomass and respiration tended to be highest around trees amended with organic fertilizers, especially the papermill biosolids:pig slurry combinations. The papermill biosolids: pig slurry combinations were generally more effective in promoting NPP than biosolids or pig slurry alone. The annual increment in tree volume is estimated to increase by 1.7 to 3.1 times when 35 kg N ha-1 were added and 2.4 to 5.3-fold when 70 kg N ha-1 were applied from organic fertilizers, compared to unfertilized controls. Our results suggest that microbial activity might have been stimulated by organic fertilizer applications, increasing nutrient availability and improving the NPP.
Key words: soil microbial community, hybrid poplar, biomass crop, organic fertilizer