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

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

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。

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 （Co）, control without N fertilizers （No）, 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 （Nz00）, 400 kg hm-2 （N400）, and 800 kg hm-2 （Ns00）. In addition, 3.72 x 104 kg hm4 flue gas desulphurization by-products （FGDB） was applied in No - Ns00 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 No treatments）. The values of microbial biomass and diversity index of all bacteria and ammonia-oxidizing microbial community were the highest in N^0 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 N~ 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.