Effect Of Rice Straw Addition On Soil Greenhouse Gas Emissios In Black Soil With Different Rice Planting Years

Soil greenhouse gas emission is a key index affecting global warming.After reclaiming and planting rice in the black soil of northeast China,there are great differences in soil organic carbon content among different rice planting years.What is the effect of rice straw returning on the greenhouse gas emission characteristics of black soil with different rice planting years?It’s not clear yet.Therefore,in this study,the black soil with different rice planting years（0 a,12 a,35 a,62 a and 85 a）was used as the research object,and the ¹³C labeled rice straw tracer technique was used in the indoor flooding incubation experiment（temperature 20℃,flooded layer 1 cm）.The effects of rice straw addition on greenhouse gas（CO₂,CH₄and N₂O）emissions in black soil with different rice years were studied,the influencing factors of soil greenhouse gas emissions were analyzed,and the priming effect of rice straw addition on soil CO₂emission was discussed.The main results are as follows:（1）The addition of rice straw increased the p H and decreased the Eh of soils with different years of planting rice（P<0.05）;On the whole,the addition of rice straw increased the contents of ammonium nitrogen and dissolve organic carbon and nitrogen in soils with different years of planting rice,and all decreased gradually with the increase of years of planting rice;In addition to planting rice for 12 years,the addition of rice straw also increased soil chitinase activity.（2）The addition of rice straw significantly promoted soil CO₂emission（P<0.05）.At the end of flooding incubation（150 days）,there was a significant positive correlation between the increase of soil CO₂emission and the number of years of rice planting（P<0.01）.The content of soil organic carbon,dissolve organic carbon and nitrogen and ammonium nitrogen had significant effects on soil CO₂emission（P<0.05）.The priming effect of rice straw addition on CO₂emission from rice planting soil was significantly lower than that of the control soil.With the extension of rice planting years,the priming effect gradually changed from negative priming（12 a）to positive priming（≥35 a）,and there was a significant positive correlation with rice planting years（P<0.01）.（3）The addition of rice straw could significantly promote soil CH₄emission（P<0.05）,which was significantly affected by the content of soil organic carbon,dissolve organic carbon and nitrogen and ammonium nitrogen.Soil CH₄emission and soil CO₂emission showed a reciprocal relationship.（4）Except for 12-year soil,the addition of rice straw significantly inhibited soil N₂O emission（P<0.05）,which was significantly affected by chitinase activity.The inhibition of soil N₂O emission increased with the increase of soil N₂O emission and decreased with the increase of soil total nitrogen content.（5）The comprehensive warming potential of soil greenhouse gas emission without rice straw mainly came from the emissions of CO₂and N₂O,while the addition of rice straw significantly increased the comprehensive warming potential of soil greenhouse gas emission（P<0.05）,mainly from the emissions of CO₂and CH₄.The addition of straw promoted soil CH₄emission and inhibited N₂O emission.