Search

Search Results

• 1. [Article] Isotopic Signatures and Concentration Profiles of Nitrous Oxide in a Rice-Based Ecosystem During the Drained Crop-Growing Season

  The stable isotopic composition of nitrous oxide (N₂O) in agricultural soils can improve our understanding of the relative contributions of the main microbial processes (nitrification and denitrification) ...

  Citation × Citation Citation Abstract Copy Title: Isotopic Signatures and Concentration Profiles of Nitrous Oxide in a Rice-Based Ecosystem During the Drained Crop-Growing Season Author: Xiong, Z. Q., Khalil, M. A. K., Xing, G., Shearer, Martha J., Butenhoff, Christopher Lee Year: 2009 The stable isotopic composition of nitrous oxide (N₂O) in agricultural soils can improve our understanding of the relative contributions of the main microbial processes (nitrification and denitrification) responsible for N₂O formation in soils, and can provide constraints for the atmospheric N2O budget. Here, we present soil profiles featuring N₂O concentrations and δ¹⁵N and δ¹⁸O values in N₂O over time, which permit the in situ identification of processes and sites of N₂O production in a rice-based ecosystem seeded with winter wheat. Our δ¹⁵N and δ¹⁸O soil profile values support the conclusion that denitrification is the dominant process behind N₂O production during the winter wheat season. The soil N₂O gas concentrations are higher below 10 cm than above 10 cm, and more depleted in ¹⁵N - N₂O at 10–15 cm depth compared to other soil depths, which indicates that the N₂O production zone is located at a depth of 10–15 cm within 0–20 cm. The δ¹⁵Nair and δ¹⁸OSMOW (δ¹⁸O of standard mean ocean water) values for soil gas N₂O averaged over the entire wheat growing season are +0.90 ± 2.9 (n = 64) and +39.3 ± 3.1 (n = 64), respectively. Given that paddy source N₂O is much heavier in both measured ¹⁵N and ¹⁸O compared to other fertilized soils, agricultural soils have been underestimated as a source of N₂O since isotopic constraints from rice agriculture have not been taken into account. Title: Isotopic Signatures and Concentration Profiles of Nitrous Oxide in a Rice-Based Ecosystem During the Drained Crop-Growing Season Author: Xiong, Z. Q., Khalil, M. A. K., Xing, G., Shearer, Martha J., Butenhoff, Christopher Lee Year: 2009 The stable isotopic composition of nitrous oxide (N₂O) in agricultural soils can improve our understanding of the relative contributions of the main microbial processes (nitrification and denitrification) responsible for N₂O formation in soils, and can provide constraints for the atmospheric N2O budget. Here, we present soil profiles featuring N₂O concentrations and δ¹⁵N and δ¹⁸O values in N₂O over time, which permit the in situ identification of processes and sites of N₂O production in a rice-based ecosystem seeded with winter wheat. Our δ¹⁵N and δ¹⁸O soil profile values support the conclusion that denitrification is the dominant process behind N₂O production during the winter wheat season. The soil N₂O gas concentrations are higher below 10 cm than above 10 cm, and more depleted in ¹⁵N - N₂O at 10–15 cm depth compared to other soil depths, which indicates that the N₂O production zone is located at a depth of 10–15 cm within 0–20 cm. The δ¹⁵Nair and δ¹⁸OSMOW (δ¹⁸O of standard mean ocean water) values for soil gas N₂O averaged over the entire wheat growing season are +0.90 ± 2.9 (n = 64) and +39.3 ± 3.1 (n = 64), respectively. Given that paddy source N₂O is much heavier in both measured ¹⁵N and ¹⁸O compared to other fertilized soils, agricultural soils have been underestimated as a source of N₂O since isotopic constraints from rice agriculture have not been taken into account. Close