长年耕作对北方旱作麦田土壤细菌群落结构及理化性质的影响

Effects of Long-term Tillage on Soil Bacterial Community Structure and Physicochemical Properties of Dryland Wheat Fields in Northern China

为探究旱作麦田长期耕作对不同土层细菌群落结构的影响及其与土壤理化性质的关系,于2016~2021年在山西农业大学闻喜旱地小麦试验示范基地开展长期定位试验,研究夏闲期免耕(NT)、深松(ST)和深翻(DP)这3种耕作方式对不同土层土壤理化性质,细菌群落α、β多样性,细菌门和属优势物种及差异物种的影响,并采用PICRUSt2预测其代谢功能.结果表明,旱作麦田连续5a深松和深翻较免耕显著提高了20~40 cm土层土壤含水量,显著降低了0~20 cm土层土壤有机碳含量;深松较深翻显著提高了0~20 cm土层土壤含水量、土壤有机碳、可溶性有机碳和可溶性有机氮含量.深松和深翻较免耕可提高0~40 cm土层土壤细菌群落的α多样性,且深松高于深翻.深松和深翻较免耕显著提高了0~20 cm土层中酸杆菌门、硝化螺旋菌门和20~40 cm土层中酸杆菌门、绿弯菌门、芽单胞菌门、Rokubacteria门、GAL15门和硝化螺旋菌门的相对丰度;显著提高了0~20 cm土层硝化螺旋菌属和20~40 cm土层Rubrobacter属和链霉菌属的相对丰度.深松较深翻显著提高了0~40 cm土层酸杆菌门、芽单胞菌门的相对丰度.冗余分析表明,0~20 cm土层的土壤有机碳、可溶性有机碳和可溶性有机氮含量对放线菌门和牙殖球菌属产生正向效应,且深松下0~40 cm土层的土壤含水量对酸杆菌门、绿弯菌门和芽单胞菌门产生正向效应.PICRUSt2预测结果表明,深松和深翻较免耕显著提高了20~40 cm土层细菌群落的氨基酸代谢和辅酶维生素代谢的相对丰度,但降低了脂质代谢的相对丰度;深松较深翻显著提高了0~40 cm土层细菌群落的氨基酸代谢和0~20 cm土层其他氨基酸代谢的相对丰度.总之,旱地麦田夏闲期深松或深翻均可提高土壤含水量、土壤细菌群落的α多样性及细菌群落的代谢能力,深松还可提高酸杆菌门和芽单胞菌门的相对丰度,并提高细菌群落的氨基酸代谢能力,从而提高了土壤可溶性有机碳、氮含量.

To explore the effects of long-term tillage on bacterial community structure in different soil layers of dryland wheat fields and its relationship with soil physicochemical properties,a long-term field experiment was conducted from 2016 to 2021 in Wenxi Experimental Demonstration Base of Shanxi Agricultural University,Shanxi Province.We studied the effects of no-tillage(NT),subsoiling-tillage(ST),and deep plowing(DP)on soil physicochemical properties;αandβdiversity of the bacterial community;and dominant and different species of phyla and genera in different soil layers.Additionally,PICRUSt2 was used to predict the metabolic function of soil bacterial community.The results revealed that subsoiling-tillage and deep plowing significantly increased the soil water content in the 20-40 cm soil layer and significantly decreased the soil organic carbon content in the 0-20 cm soil layer compared with that under no-tillage for five consecutive years.Compared with that under deep plowing,subsoiling-tillage significantly increased soil water content,soil organic carbon content,dissolved organic carbon content,and dissolved organic nitrogen content in the 0-20 cm soil layer.Compared with that under no-tillage,subsoiling-tillage and deep plowing increased theαdiversity of the soil bacterial community in the 0-40 cm soil layer,and subsoiling-tillage was higher than deep plowing.Compared with that under no-tillage,subsoiling-tillage and deep plowing significantly increased the relative abundances of Acidobacteria and Nitrospirae in the 0-20 cm soil layer and Acidobacteria,Chloroflexi,Gemmatimonadetes,Rokubacteria,GAL15,and Nitrospirae in the 20-40 cm soil layer.Compared with that under no-tillage,subsoiling-tillage and deep plowing significantly increased the relative abundance of Nitrospira in the 0-20 cm soil layer and Rubrobacter and Streptomyces in the 20-40 cm soil layer.Compared with that under deep plowing,subsoiling-tillage significantly increased the relative abundance of Acidobacteria and Gemmatimonadetes in the 0-40 cm soil layer.Redundancy analysis demonstrated that the contents of soil organic carbon,dissolved organic carbon,and dissolved organic nitrogen in the 0-20 cm soil layer exerted positive effects on Actinobacteria and Blastococcus,and the soil water content in the 0-40 cm soil layer exerted positive effects on Acidobacteria,Chloroflexi,and Gemmatimonadetes under subsoiling-tillage.The results of PICRUSt2 prediction showed that subsoiling-tillage and deep plowing significantly increased the relative abundance of amino acid metabolism and the metabolism of cofactors and vitamins but decreased the relative abundance of lipid metabolism of bacterial communities in the 20-40 cm soil layer compared with that under no-tillage.Compared with that under deep plowing,subsoiling-tillage significantly increased the relative abundances of amino acid metabolism in the 0-40 cm soil layer and other amino acid metabolism in the 0-20 cm soil layer.In conclusion,subsoiling-tillage or deep plowing could increase the soil water content,αdiversity of the soil bacterial community,and their metabolic capacity in the dryland wheat fields during the summer fallow period.The relative abundance of Acidobacteria and Gemmatimonadetes and the ability of amino acid metabolism of the bacterial community were increased by subsoiling-tillage,and thus the contents of soil dissolved organic carbon and dissolved nitrogen can be increased.