长期氮磷不同施用量对土壤细菌、硝化与反硝化微生物数量的影响

为研究长期施用氮、磷肥对土壤微生物的影响,利用荧光定量PCR方法,比较6种不同氮磷施用量处理下土壤细菌、硝化与反硝化微生物的数量差异。结果表明:1)与不施肥相比,施氮磷肥显著提高了细菌16SrRNA基因、氨氧化古菌和细菌amoA基因和反硝化细菌nirK和nosZ基因拷贝数;2)与不施肥相比,低水平(T1)到高水平(T5)氮磷肥显著提高了细菌和氨氧化古菌数量,中低水平(T2)到高水平(T5)氮磷肥显著提高了氨氧化细菌数量,中、高水平(T3-T5)氮磷肥显著提高了nirK和nosZ型反硝化细菌数量,但施氮磷肥对nirS型反硝化细菌数量影响不显著;3)各处理中,氨氧化古菌amoA基因拷贝数显著高于氨氧化细菌amoA基因,反硝化细菌nosZ基因拷贝数显著高于nirK和nirS基因,nirK基因拷贝数显著高于nirS基因;4)细菌、氨氧化古菌和细菌及nirK和nosZ型反硝化微细菌数量与土壤pH呈显著负相关关系,与其他土壤理化性质均呈显著正相关关系。此外,硝态氮含量与氨氧化古菌和细菌数量显著相关,但与反硝化细菌数量无显著相关关系。综上所述,长期施用氮磷肥显著提高了土壤细菌、氨氧化古菌和细菌及nirK和nosZ型反硝化细菌的数量,且这些微生物的数量变化对氮磷肥施用水平的响应存在差异。

Effects of long-term different N and P fertilization rates on the abundance of bacteria nitrifying and denitrifying microorganisms in soil

In this study, the abundance of total bacteria, ammonia oxidizers and denitrifying bacteria in the soils under six different N and P fertilization regimes were investigated by using real-time PCR. The results showed that:1) The N and P fertilization significantly increased the abundance of bacterial 16S rRNA gene, archaeal and bacterial amoA genes, and nirK and nosZ genes compared with CK. 2) The abundance of bacterial 16S rRNA gene and archaeal amoA gene in low rate (T1) to high rate (T5) treatments, bacterial amoA genes in moderate low rate (T2) to high rate (T5) treatments, and nirK and nosZ genes in moderate rate (T3) to high rate (T5) treatments were significantly higher than those in CK, respectively. 3) The abundance of archaeal amoA gene was significantly higher than that of bacterial, the abundance of nosZ gene was significantly higher than that of nirK and nirS genes, and the abundance of nirS gene was significantly higher than that of nirK gene in all the treatments. 4) Almost all soil properties, except soil pH, were significantly positively correlated with the abundance of bacterial 16S rRNA gene, archaeal and bacterial amoA genes, and nirK and nosZ genes. In conclusion, these results demonstrated that long-term N and P fertilization significantly increased the abundance of bacteria, ammonia-oxidizing archaea and bacteria, and denitrifying bacteria harboring nirK and nosZ genes, and the N and P fertilization rates had differential impacts on the abundance of different types of microorganisms.