The impact of atmospheric N deposition and N fertilizer type on soil nitric oxide and nitrous oxide fluxes from agricultural and forest Eutric Regosols
Biology and Fertility of Soils
Agricultural and forest soils with low organic C content and high alkalinity were studied over 17 days to investigate the potential response of the atmospheric pollutant nitric oxide (NO) and the greenhouse gas nitrous oxide (N 2 O) on (1) increased N deposition rates to forest soil; (2) different fertilizer types to agricultural soil and (3) a simulated rain event to forest and agricultural soils. Cumulative forest soil NO emissions (148-350 ng NO-N g −1 ) were~4 times larger than N 2 O
... r than N 2 O emissions (37-69 ng N 2 O-N g −1 ). Contrary, agricultural soil NO emissions (21-376 ng NO-N g −1 ) were~16 times smaller than N 2 O emissions (45-8491 ng N 2 O-N g −1 ). Increasing N deposition rates 10 fold to 30 kg N ha −1 yr −1 , doubled soil NO emissions and NO 3 − concentrations. As such high N deposition rates are not atypical in China, more attention should be paid on forest soil NO research. Comparing the fertilizers urea, ammonium nitrate, and urea coated with the urease inhibitor 'Agrotain®,' demonstrated that the inhibitor significantly reduced NO and N 2 O emissions. This is an unintended, not well-known benefit, because the primary function of Agrotain® is to reduce emissions of the atmospheric pollutant ammonia. Simulating a climate change event, a large rainfall after drought, increased soil NO and N 2 O emissions from both agricultural and forest soils. Such pulses of emissions can contribute significantly to annual NO and N 2 O emissions, but currently do not receive adequate attention amongst the measurement and modeling communities.