轮作休耕模式对土壤细菌群落的影响

Influence of rotation fallow mode on bacterial community in soil

以黄土高原半干旱区9种轮作休耕模式土壤为研究对象,分别设残膜覆盖(T1)、伏天深耕(T2)、施牛羊粪(7500 kg·hm^-2)+深翻耕(30 cm)+连续休耕3 a(T3)、施牛羊粪(7500 kg·hm^-2)+深翻耕(30 cm)+连续种植豌豆3 a并在盛花期翻压还田(T4)、施牛羊粪(7500 kg·hm^-2)+深翻耕(30 cm)+连续3 a种植豌豆(每kg豌豆种子拌根瘤菌粉8.5 g)并在盛花期翻压还田(T5)、玉米秸秆粉碎(还田量7500 kg·hm^-2)+施牛羊粪(7500 kg·hm^-2)+深翻耕(30 cm)+连续休耕3 a(T6)、玉米秸秆粉碎(还田量7500 kg·hm^-2)+施牛羊粪(7500 kg·hm^-2)+深翻耕(30 cm)+连续3 a种植毛苕子并在盛花期翻压还田(T7)、玉米秸秆粉碎(还田量7500 kg·hm^-2)+施牛羊粪(7500 kg·hm^-2)+深翻耕(30 cm)+连续3 a种植毛苕子并在盛花期翻压还田(T8)等8个处理,以连续休耕3 a为对照(CK),采用16S rRNA扩增子测序技术对土壤细菌群落组成、丰度和多样性等特征进行研究,分析了土壤养分与细菌种群多样性的相关关系。结果表明,9种休耕轮作模式下,土壤细菌群落中相对丰度较高的前5位菌门依次为变形菌门(Proteobacteria)(26.33%~37.33%)、酸杆菌门(Acidobacteria)(17.93%~21.43%)、放线菌门(Actinobacteria)(12.42%~19.41%)、芽单胞菌门(Gemmatimonadetes)(6.98%~10.99%)和绿弯菌门(Chloroflexi)(6.48%~10.50%)。其中T1、T5处理显著升高了硝化螺旋菌门的相对丰度(分别为50.04%和42.44%),T2处理显著提高了变形菌门和拟杆菌门的相对丰度(分别为31.51%和159.96%),T6、T7处理显著增加了芽单胞菌门的相对丰度(分别为28.36%和28.33%),T8处理显著增高了奇古菌门的相对丰度(519.79%)。不同轮作休耕模式的土壤全氮含量均高于CK。细菌群落丰富度指数除T7处理外,其余处理均高于CK。冗余分析和Monte Carlo置换检验结果显示,土壤全氮、全钾、速效氮含量对土壤细菌群落结构影响显著(P<0.05)。

Soil bacterial community composition,abundance,and diversity were studied in nine rotation fallow modes in semi-arid region of Loess Plateau.Nine rotation fallow treatments as:a control(CK)with continuous three years of fallow;a three-year residual plastic film mulching(T1);a three-year deep tillage in hot summer(T2);applying cattle and sheep manure of 7500 kg·hm^-2,then deep tillage of 30 cm for 3 consecutive years of fallow(T3);applying cattle and sheep manure of 7500 kg·hm^-2,after deep tillage of 30 cm planting Pisum sativum for 3 consecutive years and returning to the field in full bloom(T4);applying cattle and sheep manure of 7500 kg·hm^-2,after deep tillage of 30 cm planting Pisum sativum with rhizobium powder 8.5 g·kg^-1 for 3 consecutive years and returning to the field in full bloom(T5);corn straw chopping and returning to the field of 7500 kg·hm^-2,then deep tillage of 30 cm for 3 consecutive years(T6);corn straw chopping and returning to the field of 7500 kg·hm^-2,after deep tillage of 30 cm planting Iicia villosa and returning to the field in full bloom(T7);and corn straw chopping and returning to the field of 7500 kg·hm^-2,then applying cattle and sheep manure of 7500 kg·hm^-2,after deep tillage of 30 cm planting Vicia sativa and returning to the field in full bloom(T8).The determination of the soil bacterial community characteristics was achieved by DNA extraction followed by PCR amplification,and sequencing using the HiSeq platform.The 16 SrRNA amplifier sequencing technique was used in the study.The correlation between soil nutrients and bacterial population diversity was analyzed.The results showed that the top five phyla with highest relative abundance were Proteobacteria(26.33%~37.33%),Acidobacteria(17.93%~21.43%),Actinobacteria(12.42%~19.41%),Gemmatimonadetes(6.98%~10.99%),and Chloroflexi(6.48%~10.50%)under the nine rotation fallow modes.The relative abundance of Nitrospirae in T1 and T5 treatments significantly improved by 50.04 and 42.44%,respectively,the relative abundances of Proteobacteria and Bacteroidetes in T2 treatment significantly increased by 31.51%and 159.96%respectively,the relative abundances of Gemmatimonadetes in T6 and T7 treatments significantly increased by 28.36%and 28.33%,respectively,the relative abundance of Thaumarchaeota in T8 treatment significantly increased by 519.79%.Soil total nitrogen content of all treatments was significantly higher than that of CK.The abundance indexes(ACE and Chao1)of all treatments except T7 treatment were significantly higher than that of CK.Redundancy analysis(RDA)showed that the compositions of the soil bacterial communities were driven by several soil chemical proprieties.The Monte Carlo permutation test showed that the soil total nitrogen,total potassium,and available nitrogen contents significantly influenced the composition of the bacterial community.