Nitrous oxide emissions from irrigated and fertilized spring maize in semi-arid northern China

Abstract

As maize requires a high input of fertilizer nitrogen, it is likely to be an important source of nitrous oxide (N 2O). Detailed information on N 2O emissions over long time periods, and management practices that aim to reduce N 2O emissions from spring maize fields in China is lacking. Consequently we measured the emissions of N 2O from a spring maize field continuously from 2007 to 2009 at Yuci, Shanxi Province, China using newly developed automated chambers and explored strategies to reduce N 2O emissions. The results showed that the Optimal fertilizer treatment (120 kg N ha −1 y −1) produced the same yield of grain as the Traditional fertilizer treatment (330 kg N ha −1 y −1), and significantly reduced N 2O emissions by 48%. Topdressing with urea was the main source of N 2O, which on average accounted for 58% of the total N 2O emissions each year. Uptake of N 2O occurred during the late stage of maize growth when soil mineral N content was less than 46.4 mg N kg −1 soil. The N 2O emission factors were lower than the IPCC default value. Nitrous oxide emissions could also be reduced if farmers did not apply fertilizer N during periods of heavy rainfall and did not irrigate immediately after fertilization.