N₂O And CH₄ Emissions From Paddy Fields Under Different Water And Nitrogen Management Models And Its' Effect Of Water And Nitrogen Utilizationin On The Black Soil Region

To explore the comprehensive effects of different water and nitrogen management modes on water,gas,soil and plants in cold paddy fields,to find the best water and nitrogen management model for production increasing,to save water and reduce emissions.The experiment set up two kinds of irrigation methods?C:controlled irrigation,F:flooding irrigation?,and 4 nitrogen fertilizer levels?N0:N0:0 kg/hm²?N1:85kg/hm²?N2:110 kg/hm²?N3:135kg/hm²?,a total8 groups of water and nitrogen coupling treatment.We analyzed the CH4 and N2O emission fluxes from rice fields,calculated total emissions during the growing season,estimated greenhouse gas emissions intensity and global warming potential,made the correlation analysis with rice root system.We observed soil physical and chemical properties,fertilizer residue,rice yield and quality.And then established a projection pursuit model to comprehensively analyze various indicators.The results show that 1)controlled irrigation can reduce CH ₄ emissions by 40.5%?44.1%compare with conventional flood irrigation under the same nitrogen rate.While the effect on N₂O emissions is not significant?P>0.05?.Under the same irrigation mode,N₂O emissions increase with the increase of nitrogen fertilizer level,the emission of CH₄ decrease first and then increase with the increase of nitrogen fertilizer level.2)Controlled irrigation compare with conventional flooding irrigation,the comprehensive warming potential?GWP?of CH₄ and N₂O in paddy fields under each nitrogen treatment decrease by 35.8%?41.0%.Lowest N₂O emissions from flooding couple with 0 nitrogen fertilizer levels.Lowest CH₄ emissions from controlled irrigation couple with moderate nitrogen levels.Among the 8 treatments,there is no significant difference in GHGI between CN2 and CN3?P>0.05?,and CN2 tratement has a lower GWP.3)Both the nitrogen couple with two kinds of irrigation modes result in lower soil p H.The rate of p H decrease increase with the increase of nitrogen fertilizer level.The decline rate of FN3 treatment was the fastest,and the average decline rate was 0.023/a.4)Nitrogen couple with two kinds of irrigation modes significantly increase soil in organic nitrogen content,and the accumulation of inorganic nitrogen increase with the increase of nitrogen fertilizer level.5)Compare with conventional flooding irrigation,the controled irrigation could increase the amount of residual fertilizer by 21.7%?46.1%.The amount of residual fertilizer under controlled irrigation increase with the increase of nitrogen fertilizer level,and the amount of residual fertilizer under conventional flooding irrigation is different,and the difference is not significant.6)There is no significant difference in rice yield between controlled irrigation and conventional flooding irrigation under the same nitrogen fertilizer level.Under the same irrigation model,rice yield increase with the increase of nitrogen fertilizer level.Under the same nitrogen fertilizer level,the amylose content of rice increase by4.5%?12.3%compare with conventional flooding irrigation.Under the same irrigation mode,rice yield increase with the increase of nitrogen fertilizer level.By the optimized projection pursuit model,the economic benefits and environmental benefits of rice under different water and nitrogen management were comprehensively analyzed,and the optimal mode for controlling irrigation coupling 110kg·hm^-2 nitrogen?urea?is obtained,provide scientific data analysis and theoretical guidance for increasing production and income,efficient use of black soil resource and sustainable development of water resource.