| 摘要: |
| 【目的】研究生物结皮条件下土壤有机质及不同形态氮素含量的变化，明确生物结皮养分积累及培肥土壤的作用，为其潜在的环境风险评价提供依据。【方法】采用野外调查结合室内分析的方法，调查黄土丘陵区不同发育年限生物结皮的样地，分层采集样地的土壤样品，同时以同一区域退耕1年以内的撂荒地为对照(CK)，测定生物结皮层以及0～2，2～5，5～10 cm土层有机质、全氮及碱解氮、硝态氮、铵态氮含量。【结果】1)生物结皮条件下，结皮层土壤全氮和有机质的积累过程可分为快速增长和趋于稳定2个阶段，这2个阶段以生物结皮发育13年为界限。结皮发育13年时，结皮层土壤全氮含量达到1.34 g/kg，是对照的3.72倍；有机质含量为25.41 g/kg，是对照的5.05倍。2)生物结皮明显增加了结皮层土壤碳氮比，结皮发育15年时，结皮层土壤的碳氮比最高，为11.8，但碳氮比与发育年限无关。3)结皮层土壤碱解氮含量及其占全氮的比例明显高于0～10 cm土壤和对照，碱解氮含量在生物结皮发育15年时达到最大值（94.89 mg/kg），是对照的6.51倍，之后趋于稳定。4)生物结皮增加了结皮层土壤硝态氮和铵态氮的含量以及硝铵比。【结论】生物结皮可以明显提高结皮层土壤氮素含量，增加土壤肥力，对土壤表层氮素积累有重要作用，与此同时，生物结皮也有可能增加氮素的流失风险。 |
| 关键词: 生物结皮 土壤氮素 有机质 累积特征 |
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| 基金项目:国家自然科学基金项目(41271298)；中国科学院“西部之光”联合学者项目 |
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| Accumulation of soil organic matter and nitrogen with biological soil crust in the Hilly Loess Plateau Region |
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YAO Chun-zhu,ZHAO Yun-ge,WANG Yuan,et al
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| Abstract: |
| 【Objective】This study explored the changes of soil organic matter and nitrogen with biological soil crusts (BSCs),to understand the nutrient accumulation and the soil fertility ability of the BSCs,and provide reference for assessing the potential environmental risks.【Method】Through field survey combined with laboratory analysis,soil samples from crusts,and soil layers of 0-2 cm,2-5 cm,and 5-10 cm were collected from re-vegetated grasslands with BSCs at different ages in the Hilly Loess Plateau Region.Samples from the re-vegetated grassland with age of less than one year (fresh re-vegetated grassland) were also collected as control.Contents of soil organic matter,total nitrogen and different nitrogen components were measured.【Result】1) With BSCs,the accumulation of soil organic matter and total nitrogen had two stages.After 13 years of rehabilitation,the content of total nitrogen (1.34 g/kg) and soil organic matter (25.41 g/kg) were 3.72 and 5.05 times of those of the control,respectively.Starting from 13 years,the accumulation tended to be stable.2) Soil C/N ratio was increased by BSCs with a maximum of 11.8 after 15 years of rehabilitation.But the ratio was independent from the ages of BSCs.3) The content of soil alkali hydrolyzable nitrogen, and its ratio to total nitrogen in BSCs were higher than those in soil layer of 0-10 cm and the control.After 15 years of rehabilitation,the content of alkali hydrolyzable nitrogen reached the maximum of 94.89 mg/kg,which was 6.51 times of that of the control.4) Both the contents of nitrate nitrogen and ammonium nitrogen and the ratio of nitrate nitrogen to ammonium nitrogen in BSCs were significantly increased.【Conclusion】Biological soil crusts significantly improved soil nitrogen contents in the crust layers,increased soil fertility,and played an important role in the nitrogen accumulation in topsoil.However,BSCs may increase the risk of nitrogen losses in the slope land on the Hilly Loess Plateau. |
| Key words: biological soil crusts soil nitrogen soil organic matter evolution characteristics |
