外源碳氮对元阳梯田土壤氮素好氧矿化的影响

The Characteristics of Aerobic Mineralization of Soil Nitrogen in Yuanyang Terraced Paddy Soils

采用室内培养的生物学方法,分析了元阳梯田3个海拔梯度（高海拔：1626～1672m,中海拔：1 532～1 537 m,低海拔：1445～1459m）表层（0～ 30 em）土壤和同一海拔3个土壤层次（0～ 30,＞30～60,＞60 ～90 cm）土壤有机氮在好氧条件培养下的矿化特征.结果表明：在室内培养条件下,4种处理（对照、加碳、加氮和加碳氮）20 d的净矿化量均随土层深度的增加而降低,而在海拔梯度上没有统一的变化规律.在20d的培养期内的净矿化量总体表现为：对照和加氮处理大于加碳和加碳氮处理.4种处理净矿化量均与土壤TOC（有机碳）、TN（全氮）、DON（溶解性有机氮）、MBC（微生物碳）、ROC（易氧化碳）及LFC和LFN（轻组碳氮）呈显著性正相关（P＜0.05）.加入外源碳降低了氮素净矿化量,可减少氮的损失,说明元阳梯田土壤中的碳可能对±壤中有限氮素资源具有良好的保蓄作用.

Based on biological incubation experiments, Yuanyang terraced paddy soils were selected to study the characteristics of nitrogen （N） mineralization under aerobic conditions with 3 altitude condi- tions （ high altitude ： 1 626 - 1 672 m, middle altitude ： 1 532 - 1 537 m and low altitude ： 1 445 1 459 m） and three soil layers （0 -30, 〉30 -60, 〉60 -90 cm） in the same altitude. The results showed that for the 4 treatments （CK, adding nitrogen, adding carbon, simultaneously adding carbon and nitrogen） , the net mineralized N decreased along with the increase of soil depth. However, there was no regular relationship between the net N mineralization and altitude under aerobic condition. The net mineralized N amounts in CK and the adding nitrogen treatment were higher than the other treat- ments during the incubation time. There were significant linear relationships （ P 〈 0. 05 ） among soil TOC, TN, DON, MBC, ROC, LFC, LFN contents and the net mineralized N under aerobic condition. It showed that addition of organic carbon reduced the net N mineralization, which could reduce the loss of nitrogen from the Yuanyang terraced paddy soils with limited soil nitrogen.