放牧和氮添加对盐渍化草地土壤有机碳组分及碳储量的影响

Effects of Grazing and Nitrogen Addition on Soil Organic Carbon Fractions and Carbon Stocks in Salinized Grasslands

    摘要
  • 摘要:
    目的 探究放牧和氮添加处理下盐渍化草地土壤有机碳组分与储量的变化特征及其影响因素，对盐渍化草地生态系统的可持续发展具有重要意义。
    方法 在河西走廊盐渍化草地，设置对照（CK）、氮添加（IN）、放牧（FCK）和放牧 + 氮添加（FIN）4个处理，开展放牧（放牧强度采用适度放牧，6 ~ 9月中旬每10 d轮牧一次，共90 d）和模拟氮添加（5 ~ 9月，月初称取137.21g硝酸铵溶解在10 L水中使用喷壶均匀喷洒）定位试验，通过观测0 ~ 40 cm土壤有机碳组分、碳储量以及其它土壤基本性质指标，探讨放牧和氮添加对盐渍化草地土壤有机碳组分及其含量的影响。
    结果 ①氮添加显著增加了可溶性有机碳（DOC）含量，土壤pH、微生物生物量碳（MBC）含量显著减小（P < 0.05）。②放牧显著增加了土壤DOC、MBC含量（P < 0.05）。③放牧 + 氮添加显著增加了土壤碳库管理指数（CPMI），土壤pH显著减小（P < 0.05）。④土壤有机碳（SOC）与地上生物量（AB）显著正相关，碳储量（M）分别与土壤容重（BD）、AB显著正相关（P < 0.05）。
    结论 放牧和氮添加可以显著影响土壤有机碳库的稳定性以及活性有机碳的含量与分布，DOC、MBC含量以及CPMI能够敏感地反映土壤碳库的变化，可以作为评价放牧和氮添加引起盐渍化草地土壤有机碳变化的有效指标。

     

    Abstract:
    Objective The aims were to investigate the characteristics of soil organic carbon (SOC) fractions and reserves in salinized grassland under grazing and nitrogen (N) addition and their influencing factors, which was of great significance to the sustainable development of salinized grassland ecosystems.
    Method In the salinized grassland of Hexi Corridor, four treatments were set up, namely, control (CK), N addition (IN), grazing (FCK) and grazing + N addition (FIN), to carry out the grazing (the intensity of grazing was moderate, and the grazing was rotated once in every 10 d from June to the middle of September for a total of 90 d) and the located simulation test of addition (137.21 g of ammonium nitrate was weighed and dissolved in 10 L of water and sprayed uniformly with spraying pots from the beginning of May to the beginning of September). The experiment was conducted to observe the SOC fraction, carbon (C) stock and other basic soil property indices in 0-40 cm soil, and to explore the effects of grazing and N addition on SOC fraction and its content in salinized grassland.
    Results ① Nitrogen addition significantly increased dissolved organic C (DOC) content, and soil pH and microbial biomass C (MBC) content significantly decreased (P < 0.05). ② Grazing significantly increased (P < 0.05) soil DOC and MBC contents. ③ Grazing + N addition significantly increased soil C pool management index (CPMI) and soil pH significantly decreased (P < 0.05). ④ SOC was significantly and positively correlated with above-ground biomass (AB), and C stock (M) was significantly and positively correlated with soil bulk density (BD) and AB, respectively (P < 0.05).
    Conclusion Grazing and N addition could significantly affect the stability of SOC pools as well as the content and distribution of reactive organic C, and the DOC and MBC contents as well as CPMI could sensitively reflect the soil C pools' DOC. MBC content and CPMI could sensitively reflect the changes in soil C pools, and could be used as effective indicators to evaluate the changes in SOC in salinized grassland caused by grazing and N addition.

     

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