A six-year record of greenhouse gas emissions in different growth stages of summer maize influenced by irrigation and nitrogen management

Faced the double challenges of food security and environmental protection, optimizing crop management is essential to obtain high yield while reduce greenhouse gas (GHG) emissions. Previous studies mainly considered the GHG emissions during entire growth period as a whole but lacked information about different growth period. Here, we conducted a six-year field experiment for the first time to explore GHG emissions characteristic during three growth stages (seedling stage; ear stage; flower grain stage) of summer maize in North China Plain. Total four treatments incorporated two irrigation treatments (deficit irrigation, W1; conventional irrigation, W2) with two N levels (N reduction, N1; conventional N fertilization, N2), named as: W1N1, W1N2, W2N1, and W2N2 (CK). The high CO2 emission rate in the ear stage is significantly affected by the interaction between irrigation and fertilization, and the ear stage produced higher global warming potential (GWP) accounting for 38.3–44.2 %. The GWP was 8.88–13.3 % significantly lower in N1 than N2 in different growth stages of summer maize. Optimizing nitrogen fertilizer focused on the ear stage can help mitigate GWP. Compared with CK, GWP in W2N1, W1N2 were 29.3 % and 28.3 % lower in dry year, and 6.15–16.4 % and 8.31–25.4 % lower in normal and wet years, respectively. The conventional irrigation with N reduction produced the lowest greenhouse gas intensity and maintained the yield in dry year; deficit irrigation with conventional N treatment reduced GHG emissions while increased yield and was regarded as an effective management strategy in normal and wet years. This study provides more detailed solution for optimizing irrigation and fertilization practices to achieve the coordinated development of agricultural production and environmental sustainability.