Emissions of nitrous oxide, dinitrogen and carbon dioxide from three soils amended with carbon substrates under varying soil matric potentials

Carbon (C) substrates are critical for regulating denitrification, a process that results in nitrous oxide (N2O) and dinitrogen (N2) emissions from soil. However, the impacts of C on concomitant soil carbon dioxide (CO2) N2O under varying types water contents not well studied. Three repacked Pallic grassland soils, texture phosphorus (P) status, containing NO3−-15N were held at three levels matric potential (ψ, −3, −5 −7 kPa), while receiving daily substrate additions (acetate, glucose control) 14 days. The CO2 measured daily. Additionally, N2O:(N2 + N2O) ratios determined using 15N days 3 14. Results showed increased exponentially as gas diffusivity declined, peak higher with than acetate addition, range (± standard deviation) 0.1 ± 0.0 to 42.7 2.1 mg N m−2 h−1. highest cumulative emission (2.5 0.2 g m−2) was following addition ψ −3 kPa. In comparison added glucose, resulted twofold increase N2 soils relatively low diffusivities. N2O:(N2O N2) varied (glucose, 0.91; acetate, 0.81) day 3, had declined by (≤0.10). Cumulative enhanced increasing amended (ranging 22.5 1.3 36.6 1.8, those acetate. Collectively, demonstrate N2O, changes ratio vary over time response type diffusivity. Highlights Co-regulation assessed substrates. Soil explained concurrently emissions. Acetate reduction more glucose. effects specific.