干旱荒漠区不同灌木根际与非根际土壤氮素的含量特征

Characteristics of nitrogen content between rhizosphere and bulk soil under seven shrubs in arid desert area of China

选取广泛分布于阿拉善干旱荒漠区的白刺、霸王、红砂、沙冬青、沙木蓼、梭梭和驼绒藜7种不同的旱生灌木,研究其根际与非根际土壤各种形态氮素、有机碳的含量特征及土壤pH的变化。结果表明,相对于非根际土壤,根际土壤全氮、铵态氮、硝态氮分别平均高24.9%、24.5%和65.1%,土壤有机碳平均高出18.5%,土壤pH值平均低0.14个单位。根际与非根际土壤的全氮、铵态氮、硝态氮、有机碳和pH之间都呈现出了极显著差异(p<0.01)。7种灌木根际土壤全氮、硝态氮和有机碳含量均比非根际土壤含量高。除沙冬青根际铵态氮含量较非根际低以外,其余6种灌木根际土壤铵态氮含量均高于非根际土壤。梭梭的根际土壤pH高于非根际,其它6种灌木均是根际pH低于非根际土壤。在根际与非根际,土壤有机碳与土壤全氮之间均呈显著相关,二者表现为线性关系。而土壤全氮与铵态氮在根际与非根际则均无相关性,全氮与硝态氮在根际和非根际土壤均显著相关,且二者也呈线性相关。

Nitraria tangutorum,Zygophyllum xanthoxylum,Reaumuria soongorica,Ammopiptanthus mongolicus,Atraphaxis bracteata,Haloxylon ammodendron,Ceratoides latens,which are widely distributed in the Alashan arid desert area were selected for study.The nitrogen status of various forms,soil organic carbon content and changes of soil pH both in the rhizosphere and bulk soil.Total nitrogen,ammonium and nitrate in rhizosphere were 24.9%,24.5% and 65.1% higher than that the bulk soil.Soil organic carbon in the rhizosphere was 18.5 % higher and soil pH was lower by 0.14 units than the average.There were significant differences in content of soil total nitrogen, nitrate and organic carbon content between rhizosphere and bulk soil.Except of Ammopiptanthus mongolicus,the soil ammonium content in other shrubs′ rhizosphere was higher than bulk soil.Among the seven shrubs,only the soil pH in Haloxylon ammodendron′s rhizosphere was higher than that of the bulk soil,the soil pH under the other six shrubs.The differences soil organic carbon and soil total nitrogen between the rhizosphere and bulk soil showed a significant linear relationship.There was no correlation in soil total nitrogen and ammonium between the rhizosphere and the bulk.Soil total nitrogen and nitrate in the rhizosphere and bulk soil were significantly correlated.