PARENT SESSION
Poster Session 24: Agro-Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Soil microbial community responses to organic fertilizer applications in a wheat agroecosystem.
Dupuis, Eartha*,1, Whalen, Joann1, 1 Macdonald Campus of McGill University, Ste. Anne-de-Bellvue, Quebec, Canada
ABSTRACT- Soil microorganisms can be useful indicators of ecosystem functioning since they respond rapidly to environmental perturbations. In North America, many producers are making the transition to organic agriculture because it is more profitable than conventional agriculture. One difference between organic and conventional agriculture is the type of fertilizer applied. The diversity, activity and relative abundance of organisms in soil microbial communities is expected to be different when organic or inorganic fertilizers are applied. The objectives of this study were 1) to determine how soil microbial communities were affected by the fertilizer source applied to a wheat agroecosystem, and 2) to determine whether wheat yield and soil fertility parameters were influenced by the fertilizer source. Wheat grown in replicated agronomic research plots received the following fertilizer treatments: an unfertilized control, inorganic fertilizer (N+P), fresh broiler manure and pelletized poultry manure (7-2-1 and 5-4-2 formulations). Fertilizers were applied at rates of 60, 90, 120 and 180 kg N ha-1, wheat was harvested in mid-August 2004 and soil samples were collected after harvest. Microbial biomass and respiration were greater in plots amended with fresh broiler manure than the other fertilizer sources. Microbial community diversity was assessed by the total soil fatty acid methyl esters (TS-FAME) method. The N application rate for economical wheat production was 90 kg N ha-1, regardless of the fertilizer source, but most soil fertility parameters were not affected by the type of fertilizer applied. Our results suggest that changes in soil microbial activity and diversity occur rapidly during the conversion from conventional agriculture to organic agriculture. Assessing soil microbial communities can therefore be a powerful tool for monitoring change in agroecosystems.
Key words: soil microbial community, microbial diversity, organic agriculture, fertilizer source