Dynamique de décomposition de la litière dans les agroécosystèmes de canneberge
|Abstract:||Carbon sequestration in cranberry soils during litter burying by sanding operations can contribute fixing carbon from the atmosphere despite conversion of the original forest ecosystem into a cranberry agroecosystem. The objective of this study was to measure the kinetics of cranberry residue decomposition and carbon sequestration capacity in cranberry soils of eastern Canada. To compare cranberry agroecosystems with terrestrial ecosystems and access the effect of nitrogen fertilization on organic matter decomposition rate, first experiment was carried out in 2017 using the Tea Bag Index (TBI) where bags of teas or cranberry residues were buried then harvested 90 days later in experimental plots that received three (3) nitrogen treatments (30, 45, 60 kg N ha-1 ). A second experiment was carried out for 147 days with tri-weekly sampling to evaluate the consistency of TBI and the decomposition kinetics of carbon and biochemical fractions. To assess the influence of temperature and soil depth on CO2 emissions, soil samples were incubated at different temperatures (10, 20 and 30 °C) at different depths (0-10; 10-20; 20-30 cm). Results showed that decomposition rate of cranberry agroecosystems were in the low range among terrestrial ecosystems with high carbon sequestration capacity. Nitrogen doses do not impact importantly on TBI. The decomposition rate deviated from first order kinetics showing fractal behavior due to reduced contact between the green and rooibos teas and the immediate environment during incubation in the field. The CO2 emissions rate increased with temperature and decreased with soil depth due to changes in organic matter composition. Despite the low rate of CO2 emissions at depth (20-30 cm), the deep layers are more sensitive to temperature than upper layers (10-20 cm) and could be a risk of high rate of CO2 emissions in a context of global warming. This research demonstrated high potential for carbon sequestration in cranberry agroecosystems.|
|Document Type:||Thèse de doctorat|
|Open Access Date:||20 September 2021|
|Collection:||Thèses et mémoires|
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