1 research outputs found
Lysimeter-based full fertilizer 15N balances corroborate direct dinitrogen emission measurements using the 15N gas flow method
The N gas flux (NGF) method allows for direct in situ quantification of dinitrogen (N) emissions from soils, but a successful cross-comparison with another method is missing. The objectives of this study were to quantify N emissions of a wheat rotation using the NGF method, to compare these N emissions with those obtained from a lysimeter-based N fertilizer mass balance approach, and to contextualize N emissions with N enrichment of N in soil air. For four sampling periods, fertilizer-derived N losses (NGF method) were similar to unaccounted fertilizer N fates as obtained from the N mass balance approach. Total N emissions (NGF method) amounted to 21βΒ±β3 kg N haββ1, with 13βΒ±β2 kg N haββ1 (7.5% of applied fertilizer N) originating from fertilizer. In comparison, the N mass balance approach overall indicated fertilizer-derived N emissions of 11%, equivalent to 18βΒ±β13 kg N haββ1. Nitrous oxide (NO) emissions were small (0.15βΒ±β0.01 kg N haββ1 or 0.1% of fertilizer N), resulting in a large mean N:(NOβ+βN) ratio of 0.94βΒ±β0.06. Due to the applied drip fertigation, ammonia emissions accounted for <β1% of fertilizer-N, while N leaching was negligible. The temporal variability of N emissions was well explained by the Ξ΄N in soil air down to 50 cm depth. We conclude the NGF method provides realistic estimates of field N emissions and should be more widely used to better understand soil N losses. Moreover, combining soil air Ξ΄N measurements with diffusion modeling might be an alternative approach for constraining soil N emissions