秸秆施用及蚯蚓活动下土壤有机碳变化表征指标的筛选

在长期连续稻-麦轮作的小区试验中,通过运用主成分分析法与聚类分析法等,对施用秸秆与接种蚯蚓(Metaphire guillelmi)后土壤有机碳变化表征指标的敏感性进行了分析与评价。结果表明,不同土壤有机碳变化表征指标对农田施用秸秆与蚯蚓活动的响应不同,用所选取12种指标可较完整地表达土壤有机碳的含量与组成变化,但较多的信息及信息的不一致影响进一步的分析。各指标可依主成分分析与聚类分析结果分为两大类,一类为与土壤有机碳含量密切相关的指标,如可溶性有机碳(DOC)、热水提取态碳(HWEC)、潜在可矿化碳(PMC)、基础呼吸(BR)、酸提取态碳(AEC)、易氧化有机碳(ROC)、颗粒有机碳(POC)、轻组有机碳(LFOC)、总有机碳(TOC);另一类为与微生物密切相关的潜在影响土壤有机碳的指标,如微生物熵(Mq)、代谢熵(qCO2)与微生物生物量碳(MBC)。运用与土壤有机碳含量密切相关的指标可用于评价秸秆施用对土壤有机碳的影响,且不必全部测定,只需选测一种或两种指标,而其他指标可通过回归方程获得。与微生物密切相关的指标可用于评价蚯蚓活动对土壤有机碳的潜在影响。

INDICES FOR CHANGES IN ORGANIC CARBON IN SOILS SUBJECT TO STRAW APPLICATION AND EARTHWORM ACTIVITY

Through use of the principal component analysis(PCA) and cluster analysis(CA) methods,sensitivity was analyzed of characteristic indices of changes in organic carbon in soils subject to straw application and earthworm(Metaphire guillelmi) activity in a long-term rice-wheat rotation field experiment.Results show that these indices varied in response to straw application and earthworm activity.When all the indices chosen were used,the changes in content and composition of soil organic carbon could be reflected relatively inextenso,but too much information and inconsistency of the information embarrassed further analysis.According to the principal component analysis(PCA) and cluster analysis(CA) methods,these indices could be divided into two groups,one related to soil organic carbon content,including dissolved organic carbon(DOC),hot water extractable carbon(HWEC),potentially mineralizable carbon(PMC),basal respiration(BR),acid extractable carbon(AEC),readily oxidation carbon(ROC),particulate organic carbon(POC),light fraction organic carbon(LFOC),total organic carbon(TOC),and the other related to microbes and having some potential influence on soil organic carbon,including microbial quotient(Mq),qCO2 and microbial biomass carbon(MBC).The former could be used to evaluate effect of straw application on soil organic carbon,and the latter to evaluate potential effect of earthworm activity on soil organic carbon.