Soil profile N2O efflux from a cotton field in arid Northwestern China in response to irrigation and nitrogen management
Wennong Kuang, Yufeng Wu, Xiaopeng Gao, Mingyuan Yin, Dongwei GUI, Fanjiang Zeng
Abstract
It remains uncertain how different N inputs as synthetic fertilizer or manure and irrigation types affect nitrous oxide (N 2 O) production and effluxes in the subsurface. A field trial was carried out in 2016 to evaluate the impacts of conventional urea, animal manure, and a 50/50 mix of urea and manure on N 2 O production/effluxes from a cotton ( Gossypium hirsutum L.) field under flood or drip irrigation in northwestern China. Soil N 2 O concentrations were monitored at 5, 15, 30, and 60 cm depths to assess the production and diffusion rates of N 2 O in the soil profile. The results showed that N 2 O concentrations in 0–60 cm ranged between 221 and 532 nL L −1 and averaged 344 nL L −1 , which was generally lower compared to other studies in the same region. Manure and flood irrigation significantly increased N 2 O production at 0–5 cm and 5–15 cm, respectively. That is, the effects of nitrogen management and irrigation types on the N 2 O production of the profile were reflected in the surface layers and subsurface layers, respectively. All N 2 O production occurred in the 0–15 cm layer, with the 0–5 cm depth contributing 87%–100% of the surface emissions. The response discrepancy of N 2 O production/diffusion to irrigation and nitrogen management in different soil depths should be fully considered in developing agricultural N 2 O emission reduction measures.