Effect of slag-type fertilizers on N2O flux from komatsuna vegetated soil and CH4 flux from paddy vegetated soil

Slag-type fertilizer, which is a byproduct of the steel industry, contains high amount of active iron oxide and silica. This byproduct acts as an oxidizing agent in the agricultural soils and may have positive impact on the soil properties and plant growth. It can suppress CH4 emission, while may also affect N2O emission. A pot experiment with komatsuna and a microcosm experiment with rice were conducted to determine the effect of slag-type fertilizers (Agripower and Minekaru) on N2O and CH4 flux, respectively. The application rate of silica was kept similar for both fertilizers which caused four times higher iron application in Minekaru treatment compared to Agripower treatment. The observation results revealed that the Agripower and Minekaru treatment emitted more N2O only in the initial stage of the experiment compared to the control soil. The cumulative N2O emission over 59 days of the experiment was not significantly different between the various treatments. Minekaru-treated soil significantly decreased seasonal and cumulative CH4 flux over 112 days of the experiment compared to Agripower and control soil, while Agripower did not affect compared to the control. It was possibly due to higher iron application in Minekaru treatment than Agripower treatment. The application of Agripower and Minekaru increased shoot weight, panicle numbers, and weight of panicles in paddy. This study suggests that the application of slag-type fertilizers neither affect cumulative N2O emission nor plant biomass in komatsuna. The application of Minekaru significantly decreased CH4 evolution; while Agripower and Minekaru increased plant biomass in paddy vegetated soil.