Effects Of Irrigation Patterns And Amounts On Tomato Growth And Soil Greenhouse Gas Emissions

The greenhouse cultivation has been becoming an important part of mordern agriculture followed by the rising of its areas in recent years,and meanwhile its greenhouse gas emission has also been paid attention to more and more.In this study,we observed emission fluxes of N₂O,CO₂,and CH₄ from unplanted crop soil and potted tomato soil by static box-meteor chromatography.We studied the effects of irrigation patterns and amounts on the emission dynamics of soil N₂O,CO₂ and CH₄ during growth period,tomato growth status and soil physical and chemical properties,which will provide a theoretical basis for greenhouse gas emission reduction under greenhouse cultivation conditions,and also provide important data supports on the evaluation of environmental effects for the extension of water-saving technologies.The main results of this study were as follows:1)According to data observed from soils without crop,it was found that the N₂O flux of each treatment showed a tendency of fluctuation and decline.The total N₂O emission was as high water treatment?W3?>medium water treatment?W2?>low water treatment?W1?.The CO₂ Flux of each treatment showed a multi-peak dynamics with the changes of irrigation amount and irrigation frequency.The total CO₂ emission was as high water treatment?W3?>medium water treatment?W2?>low water treatment?W1?.Overall,soil was performed as a sink of atmospheric CH₄ for each treatment,and total uptake of CH₄ was as high water treatment?W3?>medium water treatment?W2?>low water treatment?W1?.High water treatment?W3?significantly increased the greenhouse effect.2)According to data observed from soils of pot experiment with crop of tomoto,it was found that the N₂O fluxes of soil increased significantly after two top dressings,and the N₂O emission increased with the increase of single irrigation amount.The N₂O emissions from soils under the other drip irrigation were higher than those from soils under conventional irrigation except for the minimum lower-limit irrigation?T1 and D1?.The CO₂ emissions from soils were positively correlated with the soil temperature,and increased with the increase of irrigation amount.Overall,soil was performed as a sink of atmospheric CH₄ for each treatment as well.3)During the whole growth period of tomato,the greenhouse effect,N₂O emission intensity per unit irrigation amount,CO₂ emission intensity per unit irrigation amount,CH₄uptake intensity per unit irrigation amount,and total greenhouse gas emission intensity?GHGI?per unit irrigation amount under the minimum lower-limit irrigation?T1 and D1?were obviously higher than those under the rest treatments.4)There was a negative correlation between the production of CH₄ and N₂O in dryland soils.However,due to the extremely weak emissions of CH₄ in dryland soils,it is important to consider how to reduce N₂O emissions and thus mitigate the greenhouse effect in dryland soils.5)Tomato grew best,and yield was the highest under the moderate lower-limit of irrigation?T2 and D2?.Soil pH would drop under high soil moisture content for a long time.The soil nitrate-nitrogen content decreased with the increase of irrigation amount.There was a rising in soil microbial biomass carbon in conventional irrigation compared in drip irrigation.The higher the amount of irrigation,the higher the soil microbial biomass nitrogen,and the lower the soil microbial biomass carbon content.In summary,the amount,frequency and pattern of irrigation have significant effects on N₂O,CO₂,and CH₄ emissions from greenhouse soils.The N₂O and CO₂ emissions from soil will increase with the increase of irrigation amount.The high irrigation frequency will weaken soil CO₂ emissions,and stimulate CH₄ emissions from the soil.According to comprehensive evaluation of the environmental and economic effects for each treatment conducted by using the greenhouse gas emission intensity?GHGI?per unit irrigation amount,water use efficiency?WUE?,yield,and tomato quality,the moderate limit under drip irrigation?D2?is more conducive to the water saving and emission reduction in greenhouse vegetable cultivation.The conclusion was draw from results of a crop season on pot experiment,further verification need to be done on the field experiment in greenhouse.