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时间序列下煤矸石充填复垦耕地和林地的土壤碳动态特征

Soil carbon dynamic characteristics of coal gangue-filled reclaimed cropland and forest land under time series

  • 摘要: 为明确复垦后土壤质量与土壤碳循环之间的内在机理,揭示时间序列下复垦土壤的碳动态特征规律,研究选取了山东邹城东滩矿区复垦3、6、9、12 a的耕地土壤和复垦3、12 a的林地土壤为研究对象,并以矿区内部未受塌陷影响的正常耕地和林地作为对照。通过实地采样并检测土壤总碳(TC)、总氮(TN)、土壤有机碳(SOC)、土壤微生物量碳(MBC)以及土壤理化性质(pH、AN、AP),探究时间序列下复垦重构土壤在耕地和林地2种不同利用方式下的土壤碳动态特征,及其与土壤理化性质的相关性关系。研究结果表明:复垦后耕地和林地利用方式下土壤有机碳含量均随复垦时间的增加而逐渐增加,复垦3 a和12 a的耕地和林地相比,耕地各土层深度下土壤有机碳含量均高于相应深度林地土壤;复垦12 a的耕地土壤0~20 cm有机碳含量已与对照无显著差异,复垦12 a的林地土壤40~60 cm能达到对照水平。各复垦年限耕地和林地土壤中总碳含量均高于对照,这与复垦土壤中较高比例的土壤无机碳含量有关。复垦后土壤微生物量碳呈持续增长的趋势,相同复垦年限的耕地和林地土壤相比,耕地土壤微生物量碳含量均显著高于林地,且增速更快;复垦9 a的耕地土壤微生物量碳含量已与对照无显著差异,复垦12 a的耕地土壤微生物量碳含量达到362.59 mg/kg已显著高于对照,复垦12 a的林地土壤微生物量碳含量达到110.94 mg/kg仍显著低于对照。复垦后耕地土壤微生物熵与其土壤微生物量碳含量的变化趋势相似,均呈现逐渐增加的规律。复垦6、9和12 a的耕地土壤微生物熵均显著高于对照;复垦3 a和12 a的林地土壤微生物熵均显著低于对照。复垦土壤SOC与MBC、TN、AN呈极显著正相关(p<0.01),与微生物熵q(MBC)、AP呈显著正相关(p<0.05),与pH呈显著负相关(p<0.05);MBC与TN、AN呈极显著正相关(p<0.01),与q(MBC)、AP呈显著正相关(p<0.05),与TC呈显著负相关(p<0.05)。pH与AN、AP均呈极显著负相关关系(p<0.01),与TN呈显著负相关性(p<0.05)。主要结论为伴随着复垦时间的持续,复垦后2种土地利用方式下土壤有机碳和微生物量碳含量均有不同程度的积累和恢复,而复垦后合理的农业耕作活动更有助于土壤质量的持续改善。

     

    Abstract: In order to clarify the intrinsic mechanism between soil quality and soil carbon cycling after reclamation and to reveal the characteristic patterns of carbon dynamics of reclaimed soils under time series, the cultivated soils of 3, 6, 9 and 12 a reclaimed Dongtan mine area in Zoucheng, Shandong Province and the forested soils of 3 a and 12 a reclaimed were selected for this study, and the normal cultivated and forested soils within the mine area that were not affected by the collapse were used as controls. Soil carbon dynamics characteristics of reclaimed reconstructed soils under two different utilization methods of cropland and forest land under time series and its correlation relationship with soil physicochemical properties were investigated by field sampling and testing soil total carbon (TC), total nitrogen (TN), soil organic carbon (SOC), soil microbial quantity carbon (MBC) and soil physicochemical properties (pH, AN, AP).The results of the study showed that the soil organic carbon content of both cultivated land and forest land after reclamation increased gradually with the increase of reclamation time, and compared with the cultivated land and forest land after reclamation for 3 a and 12 a, the soil organic carbon content of cultivated land at all soil depths was higher than that of forest land soil at the corresponding depths; the organic carbon content of cultivated land soil 0-20 cm after reclamation for 12 a was not significantly different from that of the control, and the forest land soil 40-60 cm after reclamation for 12 a could reach the control level. The organic carbon content of 40-60 cm of forest soils reclaimed for 12 a was not significantly different from that of the control. The total carbon content of both cropland and forest soils was higher than the control at all reclamation years, which was related to the higher proportion of soil inorganic carbon content in the reclaimed soils.The soil microbial carbon content of cultivated soils was significantly higher than that of forested soils in the same reclamation period, and the rate of increase was faster; the soil microbial carbon content of cultivated soils was no longer significantly different from that of the control at 9 a of reclamation, while the soil microbial carbon content of cultivated soils reached 362.59 mg/kg at 12 a of reclamation, which was significantly higher than that of the control. The soil microbial carbon content of the forest land was 110.94 mg/kg, which was still significantly lower than that of the control. The trends of soil microbial entropy of cultivated land and its soil microbial carbon content after reclamation were similar, both showing a gradual increase.The microbial entropy of cultivated soils at 6, 9 and 12 a of reclamation were significantly higher than the control; the microbial entropy of forest soils at 3 a and 12 a of reclamation were significantly lower than the control. Reclamation soil SOC was highly significantly positively correlated with MBC, TN, and AN (p< 0.01), significantly positively correlated withq(MBC) and AP (p< 0.05), and significantly negatively correlated with pH (p< 0.05); MBC was highly significantly positively correlated with TN and AN (p< 0.01), significantly positively correlated withq(MBC) and AP (p< 0.05), and significantly correlated with TC pH showed highly significant negative correlations with AN and AP (p< 0.01) and significant negative correlations with TN (p< 0.05). The main conclusion was that along with the duration of reclamation, soil organic carbon and microbial carbon contents accumulated and recovered to different degrees under both land use methods after reclamation, and reasonable agricultural farming activities after reclamation contributed more to the continuous improvement of soil quality.

     

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