SOIL INCUBATIONS IN POLYETHYLENE BAGS: EFFECT OF BAG THICKNESS AND TEMPERATURE ON NITROGEN TRANSFORMATIONS AND CO2 PERMEABILITY

Abstract

Ground, sieved forest floor material, collected from an interior Alaskan white spruce (Picea glauca (Moench.) Voss) stand was incubated in polyethylene bags of three thicknesses (0.015, 0.020 and 0.032 mm) at three temperatures (5, 15 and 25 °C) for periods of up to 28 d. Temperature and length of incubation proved to be more important factors affecting nitrogen mineralization than thickness of bag over the range of thicknesses tested. Regardless of temperature and time of incubation, all thicknesses of bags remained permeable to CO2. All bag thicknesses remained impermeable to H2O loss, thus ensuring constant moisture content over the duration of the experiment. An additional experiment which utilized a urea-amendment to stimulate CO2 production indicated that, even under circumstances of high CO2 evolution, the bags remained well oxygenated. Key words: Spruce (white), soil incubation, polyethylene bags, nitrogen mineralization