The interactive effects of dolomite application and straw incorporation on soil N2O emissions

Soil N2O emissions are generally larger from soil with straw incorporated, and adjusting soil pH can substantially affect the mineralization of incorporated straw. However, the interactive effects of straw return and adjustment of soil pH on N2O emissions have not been well studied. Therefore, we investigated the role of adjusting soil pH using dolomite with incorporated crop straw in changing soil properties and N2O emissions. We performed a 105-day incubation study in which dolomite was added to a rice (Oryza sativa L.) (C/N: 36) and green bean (Phaseolus vulgaris L.) straw (C/N: 17) amended acidic soil (Ultisol). The pH of the original soil (4.92) steadily increased to 5.35 and 5.45 at day 105 in rice and green bean straw treatments, respectively. Application of dolomite increased pH to a maximum value of 6.35 in the rice straw + dolomite and 6.55 in the green bean straw + dolomite amended soil at day 105 following establishment of the trial. Application of dolomite and the crop straws significantly increased soil microbial biomass C (MBC), dissolved organic C (DOC) and nitrate (NO3-), whereas it had a short-term effect on exchangeable ammonium (NH4+). The Ultisol amended with green bean straw emitted larger cumulative N2O emissions (7.25 mg N2O-N kg(-1)) during the 105-day study than soil amended with rice straw (4.23 mg N2O-N kg(-1)) and the control soil (1.42 mg N2O-N kg(-1)). Dolomite application significantly (P 0.001) decreased N2O emissions from both rice and green bean straw treatments by increasing soil pH. The results of the current study can help to mitigate N2O emissions and so improve field management.