不同化学结构外源碳添加对红壤和沙土有机碳矿化动态的影响

Effects of adding exogenous carbon with different chemical structure on the dynamics of organic carbon mineralization in red and sandy soils

外源有机碳输入是土壤有机碳(SOC)输入和输出动态平衡的重要因素。然而,当前针对不同质地土壤添加不同化学结构外源碳对有机碳矿化释放CO_(2)动态影响仍不清楚。本研究以红壤和沙土为对象,在室内培养条件下,分别添加蔗糖、淀粉、纤维素和木质素4种不同化学结构的外源有机碳,研究不同化学结构外源碳添加对有机碳释放CO_(2)速率、累积量及CO_(2)-C损失比例的影响,为深入认识土壤质地和外源碳化学结构如何驱动土壤有机碳周转提供依据。结果表明:外源碳添加能够显著提高有机碳矿化释放CO_(2)速率、累积量及CO_(2)-C损失比例,且不同化学结构外源碳添加处理存在显著差异。同时,土壤质地显著影响有机碳矿化释放CO_(2)速率、累积量及CO_(2)-C损失比例,且存在显著的外源碳×土壤质地交互效应。在不同外源碳添加条件下,沙土有机碳矿化释放CO_(2)速率、累积量及CO_(2)-C损失比例均显著高于红壤。此外,不同化学结构外源碳添加处理有机碳矿化速率的时间动态存在差异,与蔗糖相比,复杂化学结构外源碳添加下有机碳矿化释放CO_(2)速率的峰值具有滞后性。研究表明,外源碳添加对有机碳矿化的影响与外源有机碳的化学结构和土壤质地密切相关。

Exogenous organic carbon input is one of the most important factors regulating the balance of soil organic carbon (SOC) input and output.The effects of adding exogenous carbon with different chemical structures to soils with different textures on the CO_(2)emission from mineralization of organic carbon are still unclear.In this study,we added four kinds of exogenous carbon(sucrose,starch,cellulose and lignin) to red soil and sandy soil with different texture,and compared the impacts on CO_(2)release rates,cumulative amount and its proportion of CO_(2)-C loss.The aim of our study is to provide new insights on how soil texture and chemical structure of exogenous carbon drive soil organic carbon turnover.Our results showed that exogenous carbon addition increased CO_(2)release rates,cumulative amounts,and the proportion of C loss,with the magnitude of such impacts varying among different exogenous carbon treatments.Soil texture had significant effects on CO_(2)release rates,cumulative amounts,and the proportion of C loss.There were significant interactions between exogenous carbon and soil texture.Sandy soil had higher CO_(2)release rates,cumulative amounts and C loss proportion than red soil.The dynamics of CO_(2)release rates differed among exogenous carbon treatments.The peak values of CO_(2)release rate in the complex-structured organic carbon treatments were usually delayed as compared to sucrose addition.Our results suggest that the effects of exogenous carbon addition on the organic carbon mineralization are closely related to the chemical structure of exogenous organic carbon and soi texture.