Trade-offs between nitrate leaching and soil nitrous oxide emissions in the agricultural landscapes of China

Minghua Zhou1, Klaus Butterbach-Bahl1, Bo Zhu2
1 Institute of Meteorology and Climate Research-Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology
2 Institute of Mountain Hazards and Environment, CAS

O 3.2 in Fluxes between the atmosphere and ecosystems

17.07.2014, 11:20-11:40, H17

Overuse of nitrogen fertilizer is causing negative environmental impacts at either the regional or global scales due to unintended losses of reactive nitrogen to surface and groundwater bodies and the atmosphere. However, studies simultaneously quantifying gaseous and hydrological nitrogen loss pathways are scarce. In this study we provide results from a multi-year field lysimeter experiment in the Sichuan province of China where we simultaneously quantified nitrate leaching and soil nitrous oxide emissions from sloping croplands under a rain-fed wheat-maize rotation. Nitrate leaching losses were the main N loss pathway in our study region, though leaching events only occurred during the summer maize growing season. The seasonal nitrate leaching losses ranged from 28.0 to 53.3 kg N ha-1 (mean: 32.8 kg N ha-1), which corresponds to 12.7% to 35.5% (mean: 21.9%) of applied N for maize cultivation. Annual nitrous oxide fluxes from the N fertilized treatments ranged from 1.9 to 6.7 kg N ha-1 yr-1 (direct nitrous oxide emission factor: 0.12- 1.06%; mean: 0.61%). A significantly exponential decaying relationship between nitrate leaching loss and soil nitrous oxide emissions was for the first time found, suggesting that the tradeoff between nitrate leaching and nitrous oxide emission exist in the region with high nitrate leaching occurring. Thus, developing agricultural N management practices to reducing environmental risks needs to carefully consider the tradeoff between nitrate leaching and nitrous emissions. 

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last modified 2014-03-18