长期耕作对农田黑土团聚体和有机碳稳定性的影响

Effects of long⁃term tillage practices on the stability of soil aggregates and organic carbon in black soil farmland

为探明长期耕作对黑土农田土壤结构和有机碳稳定性的影响,利用黑土长期定位试验平台,应用湿筛法和红外光谱法研究不同耕作方式(灭茬起垄,CT;免耕,NT;间隔深松,ST;翻耕,MP)下0~40 cm土层土壤团聚体分布和有机碳稳定性。结果表明:与CT相比,NT和ST处理显著提高了耕层(0~20 cm)土壤超大团聚体(>2 mm)含量,NT、ST和MP处理显著提高了亚耕层(20~40 cm)土壤大团聚体(0.25~2 mm)含量,并提高了两土层团聚体平均重量直径和几何平均直径。NT处理显著提高了耕层土壤和大团聚体有机碳含量,而ST和MP处理显著增加了亚耕层土壤和大团聚体有机碳含量,其中,大团聚体对土壤有机碳的贡献率达68.9%~83.4%。NT还显著提高了耕层和亚耕层土壤及各粒级团聚体有机碳的化学稳定性。相关性分析显示,团聚体平均重量直径与土壤和大团聚体有机碳含量及其化学稳定性呈显著正相关。本研究结果可为明确黑土区不同耕作方式对农田土壤团聚体和有机碳稳定性的影响提供理论基础。

We examined the effects of different tillage practices on plough layer soil structure and organic carbon stabilization in black soil farmland with a long⁃term positioning platform.The wet⁃sieving method and infrared spectroscopy method were used to investigate the impacts of conventional tillage(CT),no⁃tillage(NT),sub⁃soiling tillage(ST),and moldboard plowing tillage(MP)on soil aggregates distribution and organic carbon characteristics in 0-40 cm soil layers.Compared to CT,both NT and ST treatments significantly increased the proportion of large macroaggregates(>2 mm)in the topsoil layer(0-20 cm)and that of small macroaggregates(0.25-2 mm)in the subsoil layer(20-40 cm)for NT,ST,and MP.NT,ST,and MP treatments resulted in higher mean weight diameter(MWD)and mean geometric diameter(GMD)of soil aggregates in both the topsoil and subsoil layers.NT treatment improved organic carbon contents in bulk soil and large macroaggregates in the topsoil layer,while ST and MP enhanced organic carbon contents in bulk soil and large macroaggregates in the subsoil layer.The contribution rate of small macroaggregates organic carbon content to the total was between 68.9%and 83.4%.Furthermore,the organic carbon chemical stabilization of soil body and aggregates increased in the topsoil and subsoil layers under NT treatment compared to others.The MWD had a positive correlation with the organic carbon content and chemical stability of soil body and small macroaggregates.These findings offered a theoretical basis for understanding the impacts of different tillage practices on the stability of soil aggregate and organic carbon in black soil region.