Abstract: 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.

Key words: Subsoiling tillage, Potato, High-throughput sequencing, Soil enzymes, Diversity of soil bacteria