外源碳氮输入对元阳梯田土壤有机氮厌氧矿化的影响

Effects of Exogenous Carbon and Nitrogen Input on Anaerobic Mineralization of Nitrogen in Yuanyang Terraced Paddy Soils

采用室内培养法研究了元阳梯田3个海拔梯度(高海拔为1626~1672 m、中海拔为1532~1537 m和低海拔为1445~1459 m)表层(0~30 cm)土壤和同一海拔3个土壤层次(0~30 cm、30~60 cm和60~90 cm)氮素在厌氧条件下的矿化特征。结果表明:4种矿化处理(对照、加碳、加氮和加碳氮)20天的培养,净矿化量均随海拔高度的降低而降低,随土层深度的增加而降低。矿化速率随培养时间呈现出下降的趋势,后期矿化量变幅缓慢。四种处理净矿化量与土壤有机碳(TOC)、全氮(TN)、溶解性有机碳氮(DOC和DON)、微生物量碳(MBC)、易氧化碳(ROC)及轻组碳氮(LFC和LFN)均呈显著性正相关(P【0.05)。20天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。表明有机碳的投入降低了净矿化,可减少氮的损失,元阳梯田土壤中的碳可能对土壤中有限氮素资源具有良好的保蓄作用。

Yuanyang terraced paddy soils were selected to study the characteristics of nitrogen(N) mineralization under anaerobic condition at three altitudes(high altitude: 1626- 1672 m, medium altitude: 1532- 1537 m and low altitude: 1445- 1459 m) and three soil layers(0- 30 cm, 30- 60 cm and 60- 90 cm) of the same altitude. The results showed that the net mineralized N decreased with the lowering of altitude and the increase of soil layer in the four treatments(CK, adding nitrogen, adding carbon, adding both carbon and nitrogen). Mineralization rate decreased with incubation time. There were significant linear relationships(P < 0.05) between soil TOC, TN, DOC, DON, MBC,ROC, LFC, LFN contents and net mineralized N, respectively. The contents of net mineralized N were higher in CK and the adding nitrogen treatments than in the adding carbon and adding both carbon and nitrogen treatments during the incubation. The results suggested that addition of organic carbon reduced the loss of N mineralization and stored N in the Yuanyang terraced paddy soils with the limited N source.