深松耕对宁南山区马铃薯田土壤细菌多样性的影响

Effect of Subsoil Plowing on Soil Bacterial Diversity in Potato Fields in Mountainous Areas of Southern Ningxia

为明确宁南山区马铃薯田不同耕作措施对土壤细菌群落组成及多样性的影响机制,2019年通过大田试验,借助Illumina MiSeq高通量测序手段,系统分析了三种不同耕作方式,即传统翻耕(CT)、深松耕30cm(STD)、深松耕50cm(STS)对0−20cm土层土壤酶活性季节变化规律、土壤全氮、有机碳含量以及土壤细菌群落组成和多样性的影响。结果表明:(1)不同耕作方式下马铃薯土壤酶活性表现出季节变化规律,对马铃薯整个生育期的土壤酶活性测定结果显示,STS较CT能显著增加尿酶活性12.9%,STS较STD和CT分别显著增加蔗糖酶活性17.1%和56.1%,STS较STD和CT处理分别增加过氧化氢酶活性27.5%和16.7%,并且深松耕处理能够显著增加土壤有机碳含量和全氮含量;(2)马铃薯田不同耕作处理下鞘氨醇单胞菌属(Sphingomonas)属于优势属,STD较CT显著增加鞘氨醇单胞菌属相对丰度24.3%。STD较CT增加Simpson指数0.72%,STS处理下Shannon指数最大,较CT处理增加6.4%,STS较CT处理显著增加Chao 1值35.1%;(3)冗余分析显示,细菌多样性(Shannon)和丰富度指数(Chao1值)均与土壤尿酶活性、全氮含量呈显著正相关,逐步回归分析得出全氮是影响宁南山区不同耕作方式下细菌丰富度和多样性的主要因素。因此,在宁南山区采用STS(深松耕50cm)模式可改善土壤酶活性和土壤性状,促进土壤细菌丰富度和多样性的增加,是维持该区马铃薯高产、生态的最佳耕作方式。

A field experiment during May 3 and October 8,2019 using Illumina MiSeq high-throughput sequencing methods systematically was conducted to examine the impact mechanisms of three different farming tillage methods(CT,traditional tillage;STD,subsoiling tillage with 30cm soil depth;and STS,subsoiling tillage with 50cm soil depth)on the composition and diversity of soil bacterial communities in potato fields in the mountainous area of southern Ningxia.The seasonal variation of soil enzyme activities,total nitrogen content,organic carbon content,and soil bacterial community composition and diversity were also analyzed.The results showed that:(1)the activities of soil enzymes showed seasonal changes during the entire growth period of potatoes under different tillage methods.STS could significantly increase the activity of urease by 12.9%as compared with CT.When compared with STD and CT,STS could significantly increase the activity of invertase by 17.1%and 56.1%,respectively.As compared with STD and CT treatment,STS increased the activity of catalase by 27.5%and 16.7%,respectively.Additionally,subsoiling treatment could be benefit for the improvement of soil organic carbon content,and total nitrogen content;(2)Sphingomonas belonged to the dominant genus under different tillage treatments in the potato field.Meanwhile,STD significantly increased the relative abundance of Sphingomonas by 24.3%as compared with CT.As compared with CT,STD increased the Simpson index by 0.72%.When compared to the CT treatment,STS significantly increased Shannon index by 6.4%,and Chao 1 value by 35.1%,respectively;(3)Redundancy analysis showed that Shannon index and richness index(Chao1 value)were significantly positively correlated with the activity of soil urease,and soil total nitrogen content.Stepwise regression analysis showed that soil total nitrogen content was the primary factor influencing soil bacterial richness and diversity under different farming methods in the mountainous area of southern Ningxia.Therefore,STS might be the superior farming method for maintaining the high yield of potatoes due to the improvements of the activities of soil enzymes,soil properties,the richness and diversity of soil bacterial community in the area.