氮肥对盐渍化枸杞园土壤微生物群落和氨氧化微生物丰度的影响

研究主要分析氮元素对宁夏平罗盐渍化枸杞园土壤中氨氧化微生物(氨氧化细菌和氨氧化古菌)的影响。实验共设八个处理:(1)C(不施氮肥,不施脱硫废弃物,原始荒地);(2)不施氮肥(N0);(3)施氮肥25 kg hm~(-2)(N25);(4)施氮肥50 kg hm~(-2)(N50);(5)施氮肥100kg hm~(-2)(N100);(6)施氮肥200 kg hm~(-2)(N200);(7)施氮肥400 kg hm~(-2)(N400);(8)施氮肥800 kg hm~(-2)(N800),在N0-N800处理施用脱硫废弃物3.72×104kg hm~(-2)。2011年8月采集0~20 cm土样。结果显示:脱硫废弃物和氮肥配合施加对土壤理化性质产生了显著影响;NO_3~--N和NH_4~+-N含量在施氮处理中相对于原始样地和不施氮处理组都有显著的升高,微生物生物量和细菌和氨氧化细菌多样性指数在施氮400 kg hm~(-2)达到最大值,施氮肥400 kg hm~(-2)是促进微生物量和群落多样性增加的最佳施用量。实时荧光定量PCR结果显示:氨氧化细菌(AOB)丰度在施氮肥400 kg hm~(-2)和800 kg hm~(-2)显著高于其它处理,脱硫废弃物和氮肥配合施用对AOB的丰度具有叠加效应。相关性分析表明:NH_4~+-N与总磷脂脂肪酸(PLFA)、细菌PLFA、革兰氏阳性菌(G+)、革兰氏阴性菌(G-)、真菌/细菌(F/B)、微生物碳(MBC)、微生物氮(MBN)及16S r RNA基因拷贝数、AOB的基因拷贝数都显著相关。因此,铵态氮是该地区微生物群落可利用的有效氮素。

Microbial Community of Ammonia-oxidizing Bacteria and Archaea Affected by Inorganic Nitrogen Fertilizer Application in Saline Soil of Lycium barbarum L.Orchard

The effects of inorganic nitrogen (N) on microbial community composition and the abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) were investigated in alkaline-saline soil of Lycium barbarum L.orchard.We carried out a long-term field experiment at Pingluo,Ningxia and there were 8 treatments including fallow(C0),control without N fertilizers (N0),and mineral fertilizer N amount of 25 kg hm-2 (N25),50 kg hm-2 (N50),100 kg hm-2(N100),200 kg hm-2 (N200),400 kg hm-2 (N~0),and 800 kg hm-2 (N~).In addition,3.72 × 104 kg hm-2 flue gas desulphurizationby-products (FGDB) was applied in N0-N~ treatments.Soil samples were collected from 0-20 cm depth in August,2011.The objective was to discuss the effects of N fertilizers and FGDB on microbial community and 16S rRNA of AOA and AOB by using phospholipid fatty acid analysis (PLFA) and real-time quantitative PCR (qPCR) analysis.FGDB together with N addition affected soil physicochemical properties.The concentration of NO3--N and NH4+-N in N treatments were higher than that in control (C and N0 treatments).The values of microbial biomass and diversity index of all bacteria and ammonia-oxidizing microbial community were the highest in N400 treatments.Therefore,400 kg N hm-2 was the optimal application amount to improve microbial biomass and community diversity in this study.The abundance of AOB was higher in N400 and N800 treatments than in other treatments.The combination application of FGDB and N fertilizer had a coupled effect on the abundance of AOB.The Pearson correlation analysis and linear regression analysis showed that NH4+-N was significantly correlated with total PLFA,bacterial,G+,G-,F/B,microbial biomass carbon (MBC),microbial biomass N (MBN),and gene abundance of 16S rRNA and AOB.This indicated that NH4+-N was a valid N resource for microbial community in this study area.