退耕还草对土壤碳库活度及团聚体活性有机碳组分分布的影响  

Changes in Soil Carbon Pool Activity and Distribution of Labile Organic Carbon Composition in Soil Aggregates Following Conversion of Farmland to Grassland on the Loess Plateau

作　　者：李映雪 臧真凤 张瑜[1,2] 王怡楠[1,2] 赵巍 LI Yingxue;ZANG Zhenfeng;ZHANG Yu;WANG Yinan;ZHAO Wei(College of Grassland Agriculture,Northwest A&F University,Yangling,Shaanxi 712100,China;State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,Northwest A&F University,Yangling,Shaanxi 712100,China;Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,Yangling,Shaanxi 712100,China)

机构地区：[1]西北农林科技大学草业与草原学院,陕西杨凌712100 [2]西北农林科技大学,黄土高原土壤侵蚀与旱地农业国家重点实验室,陕西杨凌712100 [3]中国科学院水利部水土保持研究所,陕西杨凌712100

出　　处：《水土保持研究》2023年第5期241-249,共9页Research of Soil and Water Conservation

基　　金：国家自然科学基金面上项目“黄土高原退耕还草土壤有机—无机碳耦合过程对团聚体稳定性的影响机制”(41877037)。

摘　　要：[目的]揭示黄土高原地区退耕还草对土壤团聚体活性有机碳的影响,阐明植被恢复过程中土壤碳库质量和稳定性的调控因素,为评估土壤碳固存潜力和有机碳积累机制提供理论参考。[方法]以安塞纸坊沟流域不同退耕年限(7 a,18 a,35 a和45 a)土壤为研究对象,选取耕地作对照,分析了0—10 cm土层团聚体分布及其稳定性、不同粒级团聚体(5~2 mm,2~0.25 mm,0.25~0.053 mm和<0.053 mm)有机碳含量、活性有机碳组分含量及其土壤环境影响因子。[结果]退耕还草显著提升土壤团聚体稳定性,碳库活度虽然变化不显著,但促进中活性有机碳转变为低活性有机碳,增加非活性有机碳占比,维持并提升土壤碳库质量。草地恢复影响土壤有机碳和活性有机碳在各粒级团聚体的重新分配,土壤有机碳和高、中活性有机碳主要存在于>0.25 mm粒级大团聚体中,低活性有机碳主要存在于<0.25 mm粒级微团聚体中。团聚体不同活性有机碳组分的积累主要受土壤总有机碳、可溶性有机碳、全氮和全磷等营养元素含量调控。[结论]在黄土高原植被恢复过程中,土壤结构和营养元素的综合效应共同决定活性有机碳在团聚体中的分布。[Objective]The aims of this study are to examine the impact of conversion of farmland to grassland in the region of the Loess Plateau on labile organic carbon(high,moderate,and low level)in soil aggregates,clarify the regulatory factors for soil carbon pool quality and stability during vegetation restoration,and provide theoretical reference for evaluating soil carbon sequestration potential and organic carbon accumulation mechanism.[Methods]Soil samples in four grassland restoration years(7 years,18 years,35 years and 45 years)and one sample from farmland in the 0—10 cm soil layer in Zhifanggou watershed in the hilly and gully region of the Loess Plateau were collected.The distribution and stability of aggregates,the organic carbon(SOC)and labile organic carbon(LOC)contents in soil aggregates(5~2 mm,2~0.25 mm,0.25~0.053 mm and<0.053 mm),and the correlations between labile organic carbon(high,moderate,and low level)and soil properties were analyzed.[Results]The stability of soil aggregates increased significantly with returning farmland to grassland.The quality of soil carbon pool in grasslands was higher than that in farmland.The soil carbon pool activity changed little,but the moderate-labile organic carbon(LOC-M)transformed into low-labile organic carbon(LOC-L)and the proportion of non-labile organic carbon increased.It was found that grassland restoration leaded to the redistribution of soil aggregates and labile organic carbon fractions.SOC,high-labile organic carbon(LOC-H),and LOC-M distributed mainly in macroaggregates(>0.25 mm),LOC-L in microaggregates(<0.25 mm).The soil total organic carbon,dissolved organic carbon,total nitrogen,and total phosphorus drove mainly the LOC accumulations in soil aggregates.[Conclusion]In the process of vegetation restoration on the Loess Plateau,the distribution of soil labile organic carbon in aggregates is jointly determined by the comprehensive effects of soil structure and nutrient elements.

关 键 词：土壤团聚体 活性有机碳 退耕还草 黄土高原 

分 类 号：S153.6[农业科学—土壤学]