Irrigation and tillage effects on soil nitrous oxide emissions in maize monoculture

Abstract

AbstractIrrigation and soil management can impact soil nitrous oxide (N2O) emissions. Flood and sprinkler irrigation systems together with conventional tillage are the main practices used in the high yielding maize systems in Mediterranean Spain. The objective of this field work was to quantify the effect of the irrigation system (i.e., flood, F; and sprinkler, S) and the soil tillage system (i.e., conventional tillage, CT; no‐tillage maintaining the maize stover, NTr; and no‐tillage removing the maize stover, NT) on the N2O emissions from the soil during 3 yr (2015, 2016, and 2017). S irrigation, with mean values of 1.35 kg N2O‐N ha−1 yr−1 throughout the 3 yr, obtained 42% lower N2O emissions than F irrigation. On average of the three growing seasons, yield‐scaled N2O emissions by grain yield and by grain N uptake in F irrigation were two‐fold higher than in S irrigation. Moreover, in one out of three growing seasons (2017), no‐tillage systems (i.e., NTr and NT) showed greater yield‐scaled N2O emissions compared with CT. The higher maize grain yield with the S irrigation compared to F irrigation, as well as the lower N2O emissions reported under S irrigation resulted in the reduction of the yield‐scaled N2O emissions. Our findings highlight the role of sprinkler irrigation decreasing N2O emissions in comparison to flood irrigation in Mediterranean agroecosystems.