农业资源与环境学报2026，Vol.43Issue(2)：377-386,10.DOI:10.13254/j.jare.2025.0096
坡耕地黑土有机碳含量和活性组分的坡面分异规律与影响因素
Spatial variations and determining factors of the quantity and quality of soil organic carbon along the slope of Mollisols in northeast China
摘要
Abstract
Mollisols in northeast China are predominantly distributed as sloping farmland.The erosion-deposition processes drive the redistribution and loss of soil organic carbon(SOC),representing a significant factor for the decline of organic matter within these soils.However,the spatial variations of SOC quantity and quality at the slope scale,as well as their driving mechanisms,remain unclear.This study focused on a typical sloping farmland in the Mollisol region,analyzing SOC and its labile components in the surface(0-20 cm)and sub-surface layers(20-40 cm)of different slope positions.This study aimed to explore the patterns and drivers of SOC quantity and quality variations as regulated by the erosion-deposition processes.An incubation experiment was conducted to determine SOC mineralization rates to represent its decomposability.It was showed that the SOC content exhibited a V-shaped trend of decreasing followed by increasing along the slope,and was lowest in the middle of the slope;the decrements of SOC from the top to the middle of the slope in the surface layer and the subsurface layer were 31.4％and 48.6％,respectively;and the increments from the middle to the toe of the slope were 55.6％and 219.5％,respectively.Soil readily oxidizable organic carbon(ROC)content showed the same varying pattern along the slope as SOC,and exhibited a greater changing magnitude.The content of soil dissolved organic carbon(DOC)also showed a V-shaped pattern along the slope,but the DOC content in surface soil did not rise again significantly at the toe of the slope.Consequently,the DOC/SOC ratio exhibited a decreasing trend along the slope.In contrast,the aromaticity indices of DOC(SUVA254)increased initially and then decreased along the slope,peaking at mid-slope.The decomposability of surface SOC was 11.1-17.5 times higher than that of subsurface SOC and exhibited an overall decreasing trend downslope,with the lowest levels observed in the depositional zones at the toe-slope.The correlation analysis indicated that SOC decomposability was significantly positively correlated with nitrate,available phosphorus,available potassium,DOC,ROC/SOC,and DOC/SOC,while negatively with bulk density and pH.A random forest model identified DOC as the most principal factor influencing SOC decomposability.Collectively,erosion induced synchronized declines in SOC quantity and quality in the sloping farmland of the Mollisols region,with mid-slope areas identified as"hotspots"of SOC loss.In contrast,the lower depositional zones exhibited SOC enrichment with lower decomposability compared with erosion zones,and thus might facilate soil carbon persistence.Based on the above study,it is recommended that the soil management of sloping cultivated land should focus on strengthening the carbon fixation measures in the erosion zone above and in the middle of the slope,and at the same time implement protective measures in the deposition zone below the slope and in the toe of the slope,so as to avoid the loss of organic carbon due to anthropogenic disturbances to the greatest extent possible.关键词
东北黑土/土壤侵蚀/有机碳/溶解性有机碳/有机碳矿化Key words
Mollisols in northeast China/soil erosion/soil organic carbon/dissolved organic carbon/soil organic carbon mineralization引用本文复制引用
练晶香,黎烨,丁佳艺,范益恺,樊建凌,陈增明,丁维新..坡耕地黑土有机碳含量和活性组分的坡面分异规律与影响因素[J].农业资源与环境学报,2026,43(2):377-386,10.基金项目
国家重点研发计划项目(2024YFD1500104) （2024YFD1500104）
中国科学院战略性先导科技专项(XDA28010302) （XDA28010302）
国家自然科学基金项目(42477327) （42477327）
中国科学院青年创新促进会项目(2022313) （2022313）
