Effects Of Inhibitors And Controlled Release Fertilizers On N₂O And NO Emissions From Fluvo-aquic Soil In The Old Course Of Yellow River

Nitrogen oxides?N₂O and NO?are important trace gases in the global nitrogen cycle,which directly or indirectly affect global climate change.Farmland ecosystems are important anthropogenic emissions sources of N₂O and NO,accounting for 60%and10%of the total global emissions,respectively.Inhibitors and controlled-release fertilizers are considered to be important measures to improve nitrogen use efficiency and crop yield,and reduce nitrogen-containing greenhouse gas emissions,but their effects are not consistent in different soils or planting systems.In this study,field in-situ experiments were carried out to monitor the N₂O and NO emission characteristics of farmland soil in winter wheat-summer maize rotation system by combining nitrification inhibitor with urease inhibitor?2017-2018?and combining urea with different controlled-release fertilizers?2018-2019?,respectively.To monitor the N₂O and NO emission characteristics of farmland soil in winter wheat-summer maize rotation system,analyze the influencing factors of seasonal variation of N₂O and NO emission in fluvo-aquic soil,and evaluate the effect of inhibitor and controlled-release fertilizer application on N₂O and NO emission.It provides a scientific basis for the rational operation of nitrogen fertilizer and the reduction of N₂O and NO emissions in the old Yellow River.The main results are as follows:?1?N₂O and NO emissions have obvious seasonal variation characteristics,and the peak value of emissions is after nitrogen increase,and the emission value of corn season is significantly higher than that of wheat season;The changes of soil temperature,moisture and inorganic nitrogen adjust the seasonal variation of N₂O emissions.Compared with reduced nitrogen application?RN?treatment,the application of nitrification inhibitor dicyandiamide?DCD?,3,4-dimethylpyrazole phosphate?DMPP?and 2-chloro-6-trichloromethylpyridine?CP?,the N₂O emissions in the corn season and the wheat season decreased by 26.8-79.7%and 37.8-48.3%,respectively;and the reduction of NO was 34.8-90.1%and 54.5-73.9%,of which DMPP effect was the best.Compared with RN,the application of DMPP and its combination with HQ increased corn yield by 18.6%and 20.8%,respectively?P<0.05?;the application of DCD and CP treatment also increased corn yield to a certain extent,but did not reach a significant level.The results show that the nitrification inhibitor plays an important role in reducing N₂O emissions and increasing production,among which the nitrification inhibitor DMPP has the best effect.?2?The seasonal variation characteristics of N₂O and NO emissions in 2018-2019are similar to that in the previous year.The peak emission is after increasing nitrogen.N₂O emissions mainly occur in corn season,accounting for 73%of the total annual emissions.The changes of soil temperature,moisture,inorganic nitrogen,and soluble organic carbon regulate the seasonal changes of N₂O and NO emissions.Compared with RN treatment,the emission of N₂O and NO decreased by 1.11-22.1%and 5.02-11.5%in corn season with application of 30%,50%and 70%sulfur-coated urea?SCU?,while the emission increased by 1.20-23.4%and 4.48-37.1%with the application of polyurethane coated urea?PCU?,respectively,of which 50%SCU significantly reduces N₂O and NO emissions.The effect of application of controlled-release fertilizer on N₂O and NO emission in the wheat season was not ideal.The results showed that the application of 50%SCU combined with urea was the optimal ratio of N₂O and NO emission reduction in the corn season.