秸秆还田年数对稻麦轮作农田土壤团聚体碳氮分布的影响

Effects of straw return years on organic carbon and total nitrogen distribution in soil aggregates from rice-wheat rotation fields

探究不同秸秆还田年数对稻麦复种农田土壤团聚体及其中有机碳和全氮分布的影响对提升该区土壤质量具有重要意义。田间试验始于2010年,设置秸秆不还田(NR),秸秆还田1年(SR1),秸秆还田2年(SR2),秸秆还田3年(SR3),秸秆还田4年(SR4),秸秆还田5年(SR5),秸秆还田6年(SR6),秸秆还田7年(SR7),秸秆还田8年(SR8)9个处理。结果表明,随着秸秆还田年数增加,>2 mm团聚体呈上升趋势,0.25~2 mm和<0.053 mm团聚体呈下降趋势,0.053~0.25 mm团聚体变化幅度不大。>0.25 mm大团聚体对全土有机碳和全氮的贡献率最大。土壤有机碳和全氮含量与>2 mm、>0.25 mm团聚体含量呈极显著正相关关系,与0.25~2 mm、<0.053 mm、<0.25 mm团聚体含量呈极显著负相关关系。综上所述,持续秸秆还田对改善土壤团聚体结构,促进土壤有机碳和全氮向大团聚体转移具有积极作用。

Exploring the effects of straw returning years on soil aggregates and the distribution of organic carbon and total nitrogen in rice-wheat cropping fields is of great significance for improving its soil quality.Field experiment was conducted in 2010 with 9 treatments:no straw returning(NR),1 year of straw returning(SR1),2 years of straw returning(SR2),3 years of straw returning(SR3),4 years of straw returning(SR4),5 years of straw returning(SR5),6 years of straw returning(SR6),7 years of straw returning(SR7),and 8 years of straw returning(SR8).The results showed that with the increase of straw returning years,the proportion of>2 mm aggregates increased,the proportion of 0.25-2 mm and<0.053 mm aggregates decreased,while the proportion of 0.053-0.25 mm aggregates had little change.The contributing rate of total soil organic carbon and total nitrogen was the highest in>0.25 mm macro-aggregates.Contents of soil organic carbon and total nitrogen were significantly positively correlated with the proportion of>2 mm and>0.25 mm aggregates,while negatively correlated with the proportion of 0.25-2 mm,<0.053 mm and<0.25 mm aggregates.In conclusion,continuous straw returning has positive effects on improving the soil aggregates fraction and promoting the transfer of soil organic carbon and total nitrogen to large aggregates.