Effects of five-year field aged zeolite on grain yield and reactive gaseous N losses in alternate wetting and drying paddy system.

Clinoptilolite zeolite has been widely used in agricultural production systems for enhancing water and fertilizer savings, mitigating greenhouse gas emissions, and increasing yield. However, there is little information on field-aged effects of zeolite on reactive gaseous N losses under alternate wetting and drying irrigation (AWD). We conducted a five-year field experiment to investigate field-aged effect of natural zeolite addition at 0 (Z), 5 (Z), and 10 (Z) t ha on reactive gaseous N losses (NH, NO), N-related global warming potential (GWP), soil properties and grain yield under two irrigation regimes (CF: continuous flooding irrigation; AWD) in the 4 (2020) and 5 (2021) years since its initial application in 2017. As compared with CF, AWD did not significantly affect grain yield and NH volatilization but increased seasonal NO emissions by 46 %-71 % over two years. Zeolite increased rice yield for five consecutive years. Z reduced averaged cumulative NH volatilization and GWP by 23 % and 26 %, compared to zeolite-free treatment, respectively, in the 4 and 5 years. Soil NH-N was increased with the increased rate of Z application under both CF and AWD. Z increased soil NH-N by 27 %-38 % and NO-N by 14 %-22 % in five years, compared to Z, respectively. Compared to AWD without zeolite, the addition of 10 t ha zeolite under AWD lowered NH volatilization, cumulative NO emissions, and GWP by an average of 28 %, 29 %, and 30 % in two years, respectively. IZ did not differ from IZ on reactive gaseous N losses but significantly lowered reactive gaseous losses relative to IZ. Therefore, zeolite addition could mitigate the reactive gaseous N losses and GWP for at least five years after initial application, which is beneficial to promoting zeolite application and ensuring sustainable agriculture.