覆土厚度对煤矸石充填重构土壤活性有机碳分布的影响

按照不同覆土厚度将研究区分为A(＞100 cm),B(60~100 cm),C(40~60 cm)和D(20~40 cm)4类采样区，分别采集重构土壤剖面不同深度土壤或煤矸石样品，测定其含水量(WC)、pH值、密度(BD)，以及有机碳(SOC)、可溶性有机碳(DOC)和微生物生物量碳(MBC)，研究覆土厚度对活性有机碳(AOC)分布的影响。结果表明：复垦5 a后，试验区0~20 cm土壤层SOC含量增加0.48 g/kg，DOC平均含量为46.86 mg/kg，MBC平均含量为46.09 mg/kg。与其他类型重构土壤相比，研究区有机碳库的恢复进度较慢，这主要受制于区域土壤性质和复垦地的土地利用方式。研究区相同土壤层的SOC含量大小关系为A＞B＞C＞D，也即随覆土厚度增加，煤矸石充填重构土壤SOC含量也相应增加。采样区B和C的 0~20 cm土壤层MBC含量相对较高，说明覆土厚度过薄或过厚，均不利于表层土壤MBC的积累；采样区D的煤矸石层DOC含量高达97.90 mg/kg，表层土壤中含量也达到64.80 mg/kg，均高于其他采样小区，说明覆土厚度较薄时，上覆土壤DOC含量很可能受到煤矸石层的影响。煤矸石层的qMBC值不能准确反映重构土壤肥力质量，而上覆土壤的肥力质量和SOC，我们可以用MBC来表征或预测。MBC与重构土壤pH值、BD呈极显著负相关(p＜0.01)、与WC呈显著正相关关系(p＜0.05)，而SOC和DOC与上述土壤理化性质的关系却与之相反。

Effects of topsoil thickness on active organic carbon distribution inreconstruction soil filled with coal gangue

The study area was divided into four kinds of sampling plots as A (>100 cm),B (60-100 cm),C(40-60 cm),and D (20-40 cm) according to different topsoil thicknesses.The soil or coal gangue samples from different depths of reconstruction soil profile were collected to determine their water content (WC),pH value,bulk density (BD),organic carbon (SOC),microbial biomass carbon (MBC),and dissolved organic carbon (DOC).Thus the authors studied the effect of topsoil thickness on active organic carbon (AOC) distribution.The results show that the SOC content of soil layer 0-20 cm increases 0.48 g/kg in the test field after 5 a,while DOC and MBC average content is respectively 46.86 mg/kg,46.09 mg/kg.The recovery progress of organic carbon stock from the reclaimed soil in the experimental field is slower compared with other areas,which it is mainly subject to the nature of the reclamation soil and land utilization pattern.The SOC content of the same soil layer in the test zone is in relation to A>B>C>D,namely,the SOC content of the reclaimed soil filled with coal gangue also increases with the topsoil thickness increases.The MBC content of soil layer 0-20 cm in the sampling plots B and C is relatively higher,that too thick or thin for topsoil thickness are not conducive to the MBC accumulation of surface soil.The DOC content of coal gangue layer in plot D is as high as 97.90 mg/kg,and that of surface soil also reaches 64.80 mg/kg,which is higher than that of other sampling plots.The DOC of the topsoil may be affected by coal gangue layer when the topsoil thickness is thinner.The Soil q MBC value of coal gangue layer can not accurately reflect the reconstruction soil fertility quality,but the topsoil fertility quality and SOC can be represented with its MBC content.MBC and pH value,BD show a significant negative correlation (p<0.01),while it and WC have a significant positively correlation (p<0.05).The relationship of above mentioned soil physico-chemical properties and SOC,DOC is on the contrary to MBC.