Effects Of Different Irrigation Scheduling And Irrigation Methods On Greenhouse Gas Emissions From Winter Wheat Field In The North China Plain

Severe water scarcity and increasing greenhouse gas?GHG?emissions are two essential problems of threatening sustainable development of agriculture in the North China Plain?NCP?,the largest alluvial plain and contributed more than 60%of the winter wheat?Triticum aestivum L.?production in China.For a higher and steadier yield of winter wheat,irrigation systems have been constructing widely,and irrigation water is often added as soon as possible on requirement during winter wheat production.Water management practices,such as irrigation method and irrigation scheduling,may regulate soil water status,and then affect nitrogen cycling and possibly change emission rates of soil carbon dioxide?CO₂?,methane?CH₄?,and nitrous oxide?N₂O?emissions,three important GHGs.Therefore,it is imperative to set up a suitable irrigation scheduling and irrigation methods in the winter wheat field to obtain higher grain yield,improve water use efficiency?WUE?,and mitigate GHG emissions.The present study was designed and conducted to estimate the CO₂,CH₄,and N₂O fluxes with using static chamber gas chromatography method during April–May 2017 and 2018 from winter wheat field.Randomized complete block design with two experimental factors i.e.irrigation scheduling with three lowest soil moisture limit of:?1?50%,?2?60%and?3?70%of field capacity?FC?,and irrigation method with three kinds of irrigation system:?1?surface drip irrigation?D?,?2?sprinkler irrigation?S?,and?3?flood irrigation?F?.Nine treatments were settled as labeled as D1,D2,D3,S1,S2,S3,F1,F2,and F3 respectively,and all treatments were repeated three times.The main findings are as follows:?1?The ANOVA results presented a substantial influence of irrigation scheduling and irrigation ethod on the grain yield,WUE,and IWUE in the entire study.Compared with S and F,D improved grain yield of about 5–8%and 6–7%,and improved WUE of about 1–3%and 6%in2017 and 2018,respectively.This study suggested that the combination of irrigation scheduling with soil moisture lower limit of 60%FC with the D in the winter wheat would yield the higher grain yield and optimum WUE.Moreover,D at 60%FC significantly lowered the CO₂equivalent emissions and yield-scaled GWP.Relevant data depicts that economic and environmental benefits could be attained simultaneously by combining D and lower limit of soil moisture of 60%FC for irrigating winter wheat regarding better grain yield sustainability and higher WUE in the NCP.?2?The mean seasonal soil CO₂ flux varied from 548±8 to 778±7 mg CO₂ m^-2 h^-1 and 599±1.4 o 842±3.6 mg CO₂ m^-2 h^-11 in 2017 and 2018,respectively.The maximum cumulative CO₂amount was measured in F3(10 and 11.31 Mg ha^-1 in 2017 and 2018 respectively),and the minimum cumulative CO₂ amount in D1(7.24 and 7.52 Mg ha^-1 in 2017 and 2018,respectively).The global warming potential of CO₂ emissions(GWP_CO2)during the winter wheat growing season varied from 26.56?D1?to 36.63?F3?and 27.59?D1?to 41.47?F3?Mg CO₂-eq ha^-1 in 2017 and 2018 respectively.D has the lowest soil cumulative CO₂ amount of about 7–8%and 15–13%compared with S and F in 2017 and 2018,respectively.F has about –5%and 17–14%substantially higher GWP_CO2O2 compared with S and D in 2017 and 2018, espectively.While at 70%FC level compared with 60%and 50%FC GWP_CO2O2 is notably igher approximately 7–8%and 14–24%in 2017 and 2018,respectively.D at 60%FC ompared with S and F reduced CO₂ emissions from 8–9%and 12–10%in 2017 and 2018,respectively.IS and IM markedly?P<0.001?influenced the cumulative CO₂ amount and WP_CO2O2 in both growing seasons.?3?Seasonal mean CH₄ fluxes ranged from-43.18±1.3?S1?to-61.21±0.8?D3??g CH₄ m^-2 h^-1 nd-27.52±0.8?S1?to-60±1.52?D3??g CH₄ m^-2 h^-1 in 2017 and 2018,respectively.D at 0%FC,compared with F and S,increased CH₄ uptake 8–13%and 5–4%in 2017 and 2018, espectively.The global warming potential of CH₄ uptake(GWP_CH4)ranged from-14.35?S1? o-21.58?D2?and-12.86?S1?to-19.7?D2?kg CO₂-eq ha^-1 in 2017 and 2018,respectively. ompared with S and F,D had about 13%and 6%higher GWP_CH4 in 2017,and about 10%and%higher GWP_CH4 in 2018.Scheduling level of 60%FC had about 11%and 35%higher WP_CH4 in 2017,and about 7%and 44%higher GWP_CH4H4 in 2018,compared with 70%FC and 0%FC level,respectively.In all irrigation treatments,D at 60%FC level effectively increased H₄ uptake amount and GWP_CH4H4 uptake significantly.The research results also showed that rrigating with D and at soil moisture of 60%FC is a possible choice for the local farmers of the CP to enhance the CH₄ uptake rate and higher GWP_CH4H4 uptake in winter wheat production.?4?The highest daily average N₂O pulse in response to fertilization accompanied by irrigation was btained in the F at 70%FC treatment(330.2±3.94 and 332.7±1.2?g N₂O m^-2 h^-1 in 2017 nd 2018,respectively).While the lowest peak flux was measured in D at 50%FC in both easons(168.1±1.45&154.1±6.99?g N₂O m^-2 h^-1 in 2017 and 2018,respectively).D at 60% C compared with S and F reduced N₂O fluxes 16–17%and 28–30%in 2017 and 2018, espectively.D at 50%FC compared with 60%FC and 70%FC produced 20–15%and 28–30%ower global warming potential of N₂O(GWP_N2O)emission in 2017 and 2018,respectively.The current results revealed that adopting D at 50%or 60%or 70%FC remarkably mitigates he N₂O emissions compared with S and F from winter wheat field in the NCP.?5?Multiple linear regression model illustrated that water filled pores spaces?WFPS?explained 1%,83%,and 30%of the variation in CO₂,CH₄,and N₂O fluxes,respectively.Soil emperature had no significant effect on CO₂,CH₄,and N₂O fluxes in this study.Soil nitrate itrogen?NO₃^--N?represented 72%of the variation in soil N₂O flux in entire study.?6?Compared with S and F,D has the lower total global warming potential?TGWP?of about 8% nd 15–13%,and lower yield-scaled GWP of 10–13%and 19–20%in 2017 and 2018,respectively.While compared with 60%and 70%FC,50%FC has a lower TGWP of about –14%and 13–20%in 2017 and 2018,respectively.60%FC,compared with 50%FC and 70% C level,has 3–4%and 8–9%lower yield-scaled GWP in 2017 and 2018,respectively.Among ifferent irrigation scheduling treatments,D and S at 60%and 50%FC were most persuasive in educing the accumulated seasonal fluxes and significantly reduced the TGWP and yield-scaled GWP.Variance analysis on irrigation scheduling and irrigation method showed a very remarkable?P<0.001?effect on cumulative CO₂,CH₄,and N₂O amount,TGWP,and yield-scaled GWP.