|CAI, ZEJIANG - Chinese Academy Of Agricultural Sciences|
|DUAN, YINGHUA - Chinese Academy Of Agricultural Sciences|
|XU, MINGGANG - Chinese Academy Of Agricultural Sciences|
|HANSON, BRADLEY - University Of California|
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2016
Publication Date: 11/17/2016
Citation: Cai, Z., Gao, S., Hendratna, A., Duan, Y., Xu, M., Hanson, B.D. 2016. Key factors, Soil N Processes, and nitrite accumulation affecting nitrous oxide emissions. Soil Science Society of America Journal. 80(6):1560-1571. doi:10.2136/sssaj2016.03.0089.
Interpretive Summary: Agricultural soil is a significant source of nitrous oxide (N2O) emissions contributing to global warming, and mitigation strategies depend on better understanding of the environmental factors and processes affecting its production. This study examined the dynamics of both N2O emission and N transformation processes from urea application by conducting a series of laboratory soil incubation experiments under varying conditions of application rate, soil moisture, temperature, incorporation of biochar, and the use of nitrogen transformation inhibitors (fertilizer stabilizers). Soil water content was found to be the most important environmental factor impacting N2O emissions. Much higher emissions and total gaseous N loss were found in soil above water holding capacity (WHC) than those below. This research also revealed that nitrite (NO2-) was highly correlated with N2O emission but within two distinct water content ranges (above or below WHC). Biochar and the inhibitors reduced total N2O emissions >70% and the inhibitors also significantly reduced total gaseous N loss. The research information can be used to guide development of practices for effective N management and minimizing losses.
Technical Abstract: A better understanding of the key factors affecting nitrous oxide (N2O) emission and potential mitigation strategies is essential for sustainable agriculture. The objective of this study was to examine the important factors affecting N2O emissions, soil processes involved, and potential mitigation strategies. Laboratory incubation experiments were conducted to examine separately the effects of N (urea) application rate (0–150 mg N kg-1), soil water content (5–30%, w/w), temperature (10–40 oC), incorporation of biochar (1%, w/w), an urease inhibitor (Agrotain® Ultra), and a nitrification inhibitor (N-Serve® 24) on N2O emission and N transformation dynamics in an orchard soil from California, USA. All incubation experiments were conducted at 25 oC except for the temperature experiment, which had a range of temperature treatments. Nitrous oxide emission, soil pH, and mineral N species were monitored for 35 days. Both emission rate and cumulative emissions of N2O increased at a rate much higher than N application rate increased. Soil water content at 20 and 30% [above water holding capacity (WHC) of 12%] resulted in much higher total N2O emission (9.3 and 8.0% of total soil inorganic N, respectively) than that from 5 and 10% water content (0.2 and 0.3%, respectively). Increasing soil water content to above WHC caused much higher N2O emission compared to increasing temperature, which indicates that soil moisture was more significant in affecting the process. Nitrite (NO2-) concentration was highly correlated with N2O emission but within two distinct water content ranges (above or below WHC). Amendment with biochar, Agrotain® Ultra, and N-Serve® 24 reduced N2O emission by 74%, 78%, and 74%, respectively. The results can be used to guide development of agricultural practices for minimizing N losses.