Comparative Research On Greenhousr Gas Emission And Nitrogen Leaching From Yelloe Browm Soil And Fluvo-Aquic Soil By Microplastics And Straw Inputs

Plastic products are widely used in the field of agricultural film,the coverage of China’s film has far exceeded the rest of the world.Plastic film in the air through weathering,wear and ultraviolet radiation and other forms of"microplastic"particles into the soil environment,damage the soil structure,the soil ecosystem has a series of adverse effects,because of its difficult to degrade,microplastic pollution has attracted the attention of researchers.Straw returning to field as a new fertilizer cultivation method has been widely used in farmland production.Microplastics and straw inptuts will affect soil carbon and nitrogen cycle.This study explored the environmental effects of adding straw to soil under microplastic input,which has a certain guiding significance in dealing with global warming and preventing soil pollution.In order to determine the effects of microplastics on CO₂,N₂O emission and nitrogen leaching in different soils,yellow brown soil in Dangyang,Hubei Province（S1）and fluvo-aquic soil in Xinxiang,Henan Province（S2）were selected to conduct the following laboratory culture experiment,and the main results are as follows:（1）Cumulative emissions of CO₂ and N₂O in yellow brown soil were significantly higher than those in fluvo-aquic soil,and the cumulative emissions of CO₂ and N₂O in yellow brown soil were 2.60 and 1.18 times higher than those in fluvo-aquic soil under control（without straw and microplastics）treatment,respectively.Straw addition significantly increased soil CO₂ and N₂O emissions,and the cumulative CO₂ emissions in yellow brown soil and fluvo-aquic soil increased by 4.13 and 3.18 times compared with the control,while the cumulative N₂O emissions in yellow brown soil and fluvo-aquic soil increased by 1.76 and 1.80 times,respectively,compare with addition of straw alone（1%w/w）.PLA microplastics input significantly increased soil CO₂ emission and reduced N₂O emission.Only the high amount of PLA microplastics（7%W/W）input in yellow brown soil and fluvo-aquic soil increased CO₂ emission by 71.49%and 98.96%,and N₂O emission decreased by 30.09%and 66.30%,respectively,compared with the control.On the other hand,the cumulative CO₂ emissions of both high microplastics and straw treatments were higher than those of straw treatments alone,but the cumulative N₂O emissions of the two soils showed an opposite trend.（2）High microplastics input significantly increased soil DOC and SOC contents,which increased by 80.57%and 1.88 times in yellow brown soil and 1.57 and 1.02 times in fluvo-aquic soil,respectively,compared with the control soil.However,high microplastics input significantly reduced soil mineral nitrogen content.The addition of microplastics decreased soilβ-glucoglyase activity,and the medium amount of microplastics（2%w/w）significantly decreased soilβ-glucoglyase activity,but the microplastics input increased soil urease activity,and had no significant effect on peroxidase activity.The abundance of microorganisms increased with microplastics and straw,but the copy number of each functional gene decreased with high microplastics and straw,and the copy number of AOB gene decreased by 7.49%in yellow brown soil and 10.27%in fluvo-aquic soil,respectively.（3）Nitrogen leaching characteristics of different soil types were different,straw addition significantly increased TN leaching amount,but the input of microplastics and straw reduced TN leaching amount.Compared with straw alone,the TN leaching amount of yellow brown soil with high amount of microplastics and straw input decreased 14.16%.Microplastic and straw add all can reduce the leaching liquid ammonium nitrogen content,and nitrate nitrogen content in yellow brown soil decreased after microplastics input,the nitrate nitrogen content under medium amount of microplastics input without straw addition and with straw addition decreased by 17.33%and 73.47%,respectively,but in the fluvo-aquic soil,addition of low,medium and high microplastics increased by 68.35%,87.40%and 118.01%,respectively,compared with the control.（4）The TP leaching loss was low,straw addition increased the TP leaching loss in yellow brown soil by 0.54 times compared with the control,but straw addition reduced the TP leaching loss in fluvo-aquic soil by 44.74%.Microplastics input reduced the TP leaching loss of leachate in the absence of straw,while the medium amount of microplastics input decreased by 33.33%and 20.82%in yellow brown soil and fluvo-aquic soil,respectively.However,the TP leaching loss increased with straw addition,medium amount of microplastics and straw input increased by 50.00%and 7.13%compared with straw alone in yellow brown soil and fluvo-aquic soil,respectively.