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    曹伟, 李露, 赵鹏志, 夏祥友, 王恩姮. 坡地黑土碳氮分布及其与团聚体稳定性的关系[J]. 北京林业大学学报, 2018, 40(8): 56-63. DOI: 10.13332/j.1000-1522.20170449
    引用本文: 曹伟, 李露, 赵鹏志, 夏祥友, 王恩姮. 坡地黑土碳氮分布及其与团聚体稳定性的关系[J]. 北京林业大学学报, 2018, 40(8): 56-63. DOI: 10.13332/j.1000-1522.20170449
    Cao Wei, Li Lu, Zhao Pengzhi, Xia Xiangyou, Wang Enheng. Distribution of C and N in black soil and its relationship with aggregate stability in sloping land[J]. Journal of Beijing Forestry University, 2018, 40(8): 56-63. DOI: 10.13332/j.1000-1522.20170449
    Citation: Cao Wei, Li Lu, Zhao Pengzhi, Xia Xiangyou, Wang Enheng. Distribution of C and N in black soil and its relationship with aggregate stability in sloping land[J]. Journal of Beijing Forestry University, 2018, 40(8): 56-63. DOI: 10.13332/j.1000-1522.20170449

    坡地黑土碳氮分布及其与团聚体稳定性的关系

    Distribution of C and N in black soil and its relationship with aggregate stability in sloping land

    • 摘要:
      目的探究黑土区土壤团聚体碳氮分布规律及其与团聚体稳定性的关系,进一步对比耕地与林地团聚体破坏机制差异,为退耕还林以及其他植被恢复途径提高黑土区土地生产力等方面提供理论依据。
      方法以典型黑土区长期耕作的坡耕地和樟子松坡林地为研究对象,通过不同坡位(坡上、坡中上、坡中、坡中下、坡下)和不同粒级(2~5 mm、1~2 mm、0.5~1 mm、0.25~0.5 mm、 < 0.25 mm)水稳性团聚体总碳、总氮、铵态氮、硝态氮、碳氮比(C/N)及铵态氮与硝态氮比值(ANR)的测定与分析,探究团聚体碳氮分布特征及其与团聚体破坏率之间的相关关系。
      结果坡林地土壤团聚体有机碳和总氮在坡下沉积且富集在小粒径团聚体中;耕地土壤团聚体有机碳含量及C/N显著低于林地,氮对坡位和粒径变化的响应规律不明显。铵态氮含量在 < 1 mm土壤团聚体中含量较高,硝态氮含量则在>1 mm土壤团聚体中含量较高,且林地铵态氮含量显著高于耕地。耕地团聚体破坏率显著高于林地,以>1 mm粒级团聚体破坏率的表现最为显著,坡上、坡中和坡中下2~5 mm团聚体破坏率显著高于同坡位其他粒径团聚体。团聚体碳含量和团聚体氮含量分别与团聚体破坏率呈负相关和正相关趋势,但均未达显著水平,而综合指标C/N和ANR,以及单因素铵态氮均与黑土团聚体破坏率呈显著负相关关系;当耕地团聚体破坏率超过40%时,ANR、C/N均处于较低的水平。
      结论坡耕地与坡林地之间,由于养分归还方式与土壤侵蚀环境的不同,导致土壤团聚体碳氮分布规律与团聚体稳定性的差异。坡地黑土团聚体稳定性受团聚体内部有机碳氮的共同作用,与微生物代谢密切相关的综合性指标C/N和ANR,以及被微生物优先利用的铵态氮对黑土团聚体稳定性的影响较其他指标更为显著,可在微生物活性与团聚体稳定性的关系方面做进一步研究。

       

      Abstract:
      ObjectiveThis study is to study the relationship between content and distribution of aggregate associated C and N and aggregate stability, and further analyze the difference of aggregate disruption mechanism between farmland and forested land, expectantly provide theoretical foundation for improving soil productivity by returning farmland to forestland and other vegetation rehabilitation measures in black soil region.
      MethodIn our study, a sloping farmland (preceding crop is corn) and an adjacent sloping forestland (artificial Pinus sylvestris forest) in typical black soil region of northeastern China were selected and each slope was divided into the upper slope position, upper to middle slope position, middle slope position, middle to lower slope position, and lower slope position along the three sampling lines which parallelled to the slope aspect. The soil samples were sieved individually and separated into five aggregate-size fractions (2-5 mm, 1-2 mm, 0.5-1 mm, 0.25-0.5 mm, < 0.25 mm) using the dry sieving and wet sieving method, then the percentage of aggregate disruption (PAD) of each fraction was calculated. Each fraction of soil water stable aggregates was passed through 0.25 mm sieve to determine aggregate-associated organic carbon, total nitrogen, ammonium-N, nitrate-N, and the ratio of ammonium-N to nitrate-N (ANR).
      ResultIn sloping forestland, aggregate-associated C and N deposited in the lower slope position and accumulated in smaller aggregates; aggregate-associated C and C/N in farmland was significantly lower comparing with which in forestland; but aggregate-associated N did not show a distinct trend with the change of slope position and aggregate size. Aggregate-associated ammonium-N predominated in < 1 mm aggregates and which of forestland was higher than farmland; however, aggregate-associated nitrate-N mainly concentrated in >1 mm aggregates. PAD was affected obviously by land use type, aggregate size and slope position: PAD of farmland was significantly lower than forestland especially for >1 mm; PAD of 2-5 mm in upper, middle, middle to lower slope positions was obviously higher than other aggregate sizes in the same slope position.Aggregate-associated C and N did not present a significantly negative and positive relationship with PAD at significance level of 0.05; but C/N, ANR and ammonium-N were negatively correlated with PAD, and both ANR and C/N were in a lower level when PAD was greater than 40%.
      ConclusionDistribution of aggregate-associated C and N and aggregate stability between farmland and forestland are caused by the difference of nutrient restitution and soil erosion environment. Aggregate stability of black soil is determined by the interaction of aggregate-associated C and N, not the individual concentration of aggregate-associated C or N. The integrated indicators C/N and ANR, which are closely related to soil microorganism, have significant influence on soil aggregate disruption; moreover, ammonium-N used by microorganism preferentially in the soil environment also shows a significant correlation with aggregate stability. In the future, we should pay more attention to the relationship between microorganism activity and soil aggregate stability.

       

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