青藏铁路沿线土壤有机碳和速效养分空间分异特征

Soil organic carbon and available nutrients at different transects along Qinghai-Tibet railway

研究了青藏铁路沿线由北至南27条样带的土壤有机碳和速效养分特征,分析指标包括活性有机碳、可溶性有机碳、碱解氮、铵态氮、硝态氮、速效磷、速效钾。结果表明:沿线土壤有机碳和速效养分指标多表现为土壤下层(20-40cm)养分含量低于表层(0-20cm)。南北各样带的综合分析表明,土壤活性有机碳、可溶性有机碳、碱解氮、铵态氮、表层速效磷含量表现为南部西藏境内各样带多高于北部青海境内样带;而土壤硝态氮、速效钾、下层速效磷含量由北至南则没有明显的增高趋势。各样带土壤活性有机碳含量多在2-14g·kg^(-1)之间,碱解氮含量多在20-160mg·kg^(-1)之间,碱解氮与活性有机碳表现出非常类似的变化规律。各样带土壤可溶性有机碳含量变动在200-450mg·kg^(-1)之间,铵态氮含量多在5-9mg·kg^(-1)之间,这两个指标由北至南在各样带间波动比较大。沿线各样带土壤硝态氮含量在2-5mg·kg^(-1)之间,速效磷含量多在1-3.5mg·kg^(-1)之间,速效钾含量则多在30-100mg·kg^(-1)之间。相关性分析表明,碱解氮与活性有机碳及可溶性有机碳之间均呈现极显著正相关,活性有机碳与可溶性有机碳之间也存在极显著正相关关系,活性有机碳与速效磷之间存在显著正相关关系,硝态氮与速效钾存在显著正相关关系,而其余各养分指标之间则没有明显相关性。

Soil organic carbon and available nutrients of different vegetation transects along Qinghai-Tibet railway were studied from north to south. Totally 27 transects were investigated,and the soil indexes include soil active organic carbon,dissolved organic carbon,available nitrogen,ammonia nitrogen,nitrate nitrogen,available phosphorus and available potassium. The results showed most of the indexes in the lower layer were less than that in upper layer. Some indexes showed the trend that the index value of transects in the Qinghai Province were less than the value in the Tibet,including active organic carbon,dissolved organic carbon,available nitrogen,ammonia nitrogen and available phosphorus in the upper soil layer. While the other indexes had different trend. The nitrate nitrogen,available potassium and available phosphorus in the lower soil layer in the northern part of railway were not obvious less than that in the southern part. The content of soil active organic carbon in the transects along railway was in the range of 2-14 g · kg-1,while the content of soil available nitrogen was within 20-160mg·kg-1; available nitrogen and active organic carbon had a very similar change regulation. The content of dissolved organic carbon was within 200-450mg·kg-1,while the soil ammonia nitrogen content was within 5-9mg·kg-1; the two indexes both had a larger fluctuation from the north to south along the transects. The content of soil nitrate nitrogen was within 2-5mg·kg-1,the content of soil available phosphorus was within 1-3.5mg·kg-1,the content of available potassium was within 30-100mg·kg-1. Correlation analysis was used to explore the relationship between all the indexes along railway. Results showed that the available nitrogen had very significant positive correlation with active organic carbon and dissolved organic carbon. In addition,there was a very significant positive correlation between the active organic carbon and dissolved organic carbon. The active organic carbon had significant positive correlation with available phosphorus,and the nitrate nitrogen had significant positive correlation with available potassium. However,there wasn＇t significant correlation between any other two indexes of the remaining available nutrient elements.