Emissions of nitrous oxide, dinitrogen and carbon dioxide from three soils amended with carbon substrates under varying soil matric potentials. (14th May 2021)

• Record Type: Journal Article
• Authors: Li, Yuan; Clough, Timothy J.; Moinet, Gabriel Y. K.; Whitehead, David
• Is Part Of: European journal of soil science. Volume 72:Number 5(2021)
• Page Start: 2261
• Page End: 2275
• Publication Date: 2021-05-14
• Subjects: acetate -- glucose -- greenhouse gas emissions -- matric potential -- soil diffusivity; Soil science -- Periodicals; 631.4
• DOI: 10.1111/ejss.13124
• Languages: English
• ISSNs: 1351-0754

Abstract

Abstract: Carbon (C) substrates are critical for regulating denitrification, a process that results in nitrous oxide (N2 O) and dinitrogen (N2 ) emissions from soil. However, the impacts of C substrates on concomitant soil emissions of carbon dioxide (CO2 ) and N2 O under varying soil types and soil water contents are not well studied. Three repacked Pallic grassland soils, varying in texture and phosphorus (P) status, containing NO3 − ‐ 15 N were held at three levels of matric potential ( ψ, −3, −5 and −7 kPa), while receiving daily substrate additions (acetate, glucose and water control) for 14 days. The CO2 and N2 O emissions were measured daily. Additionally, the N2 O:(N2 + N2 O) ratios were determined using 15 N on days 3 and 14. Results showed that N2 O emissions increased exponentially as soil gas diffusivity declined, and N2 O peak emissions were higher with glucose than with acetate addition, with a range (± standard deviation) of 0.1 ± 0.0 to 42.7 ± 2.1 mg N m −2 h −1 . The highest cumulative N2 O emission (2.5 ± 0.2 g N m −2 ) was measured following glucose addition with a soil ψ of −3 kPa. In comparison with added glucose, acetate resulted in a twofold increase in N2 emissions in soils with relatively low gas diffusivities. The N2 O:(N2 O + N2 ) emissions ratios varied with substrate (glucose, 0.91; acetate, 0.81) on day 3, and had declined by day 14 under substrate addition (≤0.10). Cumulative CO2 emissions were enhanced with increasing soil gas diffusivity and were higher for soils amended with glucose (ranging from 22.5 ± 1.3 to 36.6 ± 1.8, g C m −2 ) than for those amended with acetate. Collectively, the results demonstrate that the increase of N2 O, N2 and CO2 emissions and changes in the N2 O:(N2 + N2 O) ratio vary over time in response to C substrate type and soil gas diffusivity. Highlights: Co‐regulation of CO2 and N2 O emissions was assessed for varying soil types and C substrates. Soil diffusivity explained concurrently cumulative N2 O and CO2 emissions. Acetate enhanced N2 O reduction to N2 in three grassland soils more than glucose. C substrate effects on soil N2 O, N2 and CO2 emissions were soil type specific.