A novel method to measure the effect of temperature on diffusion of plant-available nitrogen in soil
2012
Inselsbacher, Erich | Näsholm, Torgny
BACKGROUND AND AIMS: Soil temperature influences nitrogen (N) diffusion in soil but until now, such effects have been difficult to quantify. This study aimed at estimating the effect of temperature on the diffusive fluxes of plant-available N forms in two contrasting soils. METHODS: Using a novel technique based on micro-dialysis, we established relationships between diffusive fluxes and temperature in aqueous solutions and in soil samples. RESULTS: Averaged for all compounds, the decreases of diffusive fluxes from the soil to the microdialysis sampler were 3.8 and 4.7% per degree Celsius in an agricultural and a boreal forest soil, respectively. The temperature-related shift of diffusive flux was, however, significantly dependent on molecular weight of the N compound. In accordance with established functions for temperature effects on diffusive fluxes, the non-linearity of this relationship resulted in a greater temperature response for small N compounds compared to larger compounds. CONCLUSIONS: Our results show that, all other factors being equal, the relative contribution of smaller N compounds to the diffusive flux of total plant-available N increases with increasing soil temperatures.
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