Simultaneous determination of molecular nitrogen (N2) and nitrous oxide (N2O) in biochar-treated arable soils: Poster präsentiert bei der DASIM-Konferenz „Tracing Denitrification“ 12-14. März 2019, Gießen, Deutschland
The long-term effects of biochar (BC) application on denitrification, especially on the end product N2, still remain unclear, amongst others due to methodological difficulties. Thus, the aim of our work was (i) to investigate N2 and N2O emissions from BC-treated soils using the Helium gas-flow core method, which allows to measure the two gases simultaneously, and (ii) to determine potential controlling factors that might be affected by BC-application. For this, soil samples from two sites in Austria were obtained. At Traismauer, undisturbed soil samples (Cambisol, pH 7.5) were taken from three BC-treated (3 % BC) and three NPKfertilized plots (control). At Kaindorf, two BC-compost treatments (0.5 to 1 % BC, one with additional N fertilization) and a control (Chernozem, pH 6.6) were sampled. The N gas emission rates were determined at two different water contents [Traismauer: 50 and 70 % water-filled pore space (WFPS); Kaindorf: 23 and 50 % WFPS] and at up to three different temperatures. For both sites, physicochemical and microbial properties were also measured. The BC-treated samples emitted on average more N2 compared to the control samples except for the Kainsdorf samples at 50 % WFPS. In general, N gas emissions increased with increasing water content. For Traismauer, the highest mean N2 emission rates were measured from BC-treated samples at 5 °C for both water contents. Gaseous N losses as N2O were always lower compared to N2 fluxes at both sites. For the Traismauer samples, N2O was detected only sporadically. For the Kaindorf samples, N2O emissions were detectable in all cases. The highest N2O emission rates were determined from N-enriched
BC-treated samples. The N2:N2O ratio ranged from 3.3 to 38.3. The physicochemical and microbial properties determined could not explain the differences in N gas emission rates.
