岩溶区不同土地利用方式对土壤有机碳碳库及周转时间的影响

通过土壤样品的室内培养,运用三库一级动力学理论,分析桂林毛村典型岩溶区旱地、灌丛、果园、林地4种不同土地利用类型下石灰土有机碳库容大小、各碳库平均周转时间及其影响因素。结果表明:4种土地利用类型土壤有机碳含量分别为15.41～20.10g/kg,13.07～31.16g/kg,9.38～14.74g/kg,30.82～37.52g/kg。活性有机碳占总有机碳的比例最小,分别为0.61%～0.93%,0.95%～1.24%,0.77%～1.00%,1.49%～1.66%。缓效性有机碳库分别占总有机碳含量的21.13%～30.18%,13.58%～23.46%,29.54%～46.58%,30.39%～33.84%。平均周转时间分别为7,8,7,12年。惰性有机碳占总有机碳的比例最高,分别为69.18%～78.26%,75.27%～85.47%,56.63%～69.70%,64.64%～68.12%。延长缓效性碳库驻留时间在一定程度上是提高土壤有机碳库的关键因素。相关分析表明,土壤有机碳总量、土壤碳酸钙含量、总钙量、土壤pH值、全氮含量、C/N与土壤有机碳各库库容及周转时间存在显著的正相关,腐殖质含量与土壤有机碳库及周转时间呈极显著正相关,土壤过氧化氢酶及脲酶活性显著影响土壤有机碳库含量及周转时间。

The Impact of Different Soil Types on Soil Organic Carbon Pool and Turnover in Karst Area

On the base of first order dynamic model,combining with a laboratory soil incubation experiment,the dynamic of soil organic carbon(SOC) decompositions,three carbon pool sizes and average turnover time were analyzed,including cultivated land,shrub,orchard and forest four different land use types brown calcareous soil of typical Karst area in Maocun of Guilin.The results show that four soil types total soil organic carbon are 15.41~20.10 g/kg,13.07~31.16 g/kg,9.38~14.74 g/kg,30.82~37.52 g/kg,respectively.The size of active SOC pool is smallest,respectively accounts to 0.61%~0.93%,0.95%~1.24%,0.77%~1.00%,1.49%~1.66%.Slow SOC pool is 21.13%~30.18%,13.58%~23.46%,29.54%~46.58%,30.39%~33.84%,and the average turnover time is 7,8,7,12 years respectively.The passive SOC pool is largest,and account to 69.18%~78.26%,75.27%~85.47%,56.63%~69.70%,64.64%~68.12%.To a certain extend the turnover time of slow SOC pool is a key factors of improve the reserve of total SOC.The organic carbon pool size and turnover time had significant positive correlations with total soil organic carbon,calcium carbonate content,total calcium,soil pH,total nitrogen,C/N.Humus content and soil organic carbon pool and turnover time had a significant positive correlation.The activies of soil catelase and urease significantly affected soil organic carbon content and turnover time.