Pulse emissions of N2O and CO2 from an arable field depending on fertilization and tillage practice

Nitrous oxide (N2O) emissions from soil are characterized by strong emission pulses. Although several mechanisms are known to create them, pulses are difficult to predict. Currently there is no established systematic way to identify pulses from long-term static chamber measurement results. In this study we suggest a simple algorithm for pulse identification. The algorithm was applied on time series of N2O and carbon dioxide (CO2) fluxes from a field study on the long-term impact of fertilization and tillage practice. Between 4 and 9% of N2O values were pulse values; 20–60% of total emission was emitted as pulses. Minimum tillage resulted in more pulses than plowing. In contrast, long-term averages of N2O losses from nitrogen (N) fertilizer were similar (3–4%) for all management practices. N2O emissions per crop yield for increased fertilization practice were double the values for reduced fertilization practice independent of tillage practice. CO2 emission pulses were scarce and there was no significant effect of management practice on CO2 pulse probability.

► Pulse values were identified from long-term N2O and CO2 flux measurements.
► Between 20 and 60% of total N2O emission was released as pulses.
► Minimum tillage increased N2O pulse occurrence.
► Relative N2O losses from fertilizer were almost independent of management practice.
► Increased fertilization resulted in higher N2O emission per crop yield.