深松和秸秆还田对灌耕灰钙土土壤细菌多样性和群落结构的影响

Effects of subsoiling and the return of straw on soil bacterial diversity and community structure in an irrigated sierozem farmland

为探究深松和秸秆还田对土壤细菌多样性和群落结构的影响,于2015—2020年在甘肃引黄灌区灰钙土上开展田间试验,研究旋耕(RT)、深松(ST)和深松秸秆还田(STS)对0~20 cm土层土壤理化性状和细菌群落的影响。结果表明,与RT和ST相比,STS显著提高了土壤肥力、细菌OTU数目和α多样性,土壤细菌群落存在显著分异。土壤pH、有机碳(SOC)、土壤含水量(SWC)、阳离子交换量(CEC)、全氮(TN)、碱解氮(AHN)与细菌α多样性具有显著或极显著的相关性。土壤优势菌门为变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、拟杆菌门(Bacteroidetes)、放线菌门(Actinobacteria)、绿弯菌门(Chloroflexi),与RT和ST相比,STS处理变形菌门和拟杆菌门相对丰度显著增加2.72~10.40个百分点,酸杆菌门相对丰度显著降低6.98~11.10个百分点。优势菌属为芽孢杆菌属(Bacillus)、酸杆菌属(Acidibacter)、假节杆菌属(Pseudarthrobacter)、黄杆菌属(Flavobacterium)、小梨菌属(Pirell),与RT和ST相比,STS处理下芽孢杆菌属、酸杆菌属、假节杆菌属、黄杆菌属相对丰度显著增加0.52~4.13个百分点。土壤pH、SWC及SOC、TN含量与拟杆菌门相对丰度呈显著正相关(P<0.05),SOC、TN、AHN含量及CEC与芽孢杆菌属、酸杆菌属、假节杆菌属相对丰度呈显著正相关(P<0.05)。冗余分析结果表明,土壤SOC、pH、SWC、CEC和速效钾(AK)是影响灰钙土土壤细菌群落变异的主要环境因素。PICRUSt功能预测结果表明,新陈代谢为灰钙土细菌群落主要的一级功能。综上,深松秸秆还田可提高灰钙土土壤肥力和细菌多样性,改善农田土壤微环境。

A field experiment was conducted to study the effect of 35 cm subsoiling with the return of maize straw(STS),35 cm subsoiling(ST),and conventional rotary tillage(RT)on the soil properties,soil bacterial diversity,and the community structure at a depth of 0–20 cm on irrigated sierozem in the Gansu Yellow River irrigated area in 2015—2020.Results showed that,compared with RT and ST,STS could promote soil fertility,increase bacterial OTU numbers and the bacterial Alpha diversity.The distribution characteristics of the soil bacterial communities were significantly different.The soil pH,organic carbon(SOC),water content(SWC),cation exchange capacity(CEC),total nitrogen(TN),and alkali-hydrolyzable nitrogen(AHN)had significant or extremely significant correlations with bacterialα-diversity.Proteobacteria,Acidobacteria,Bacteroidetes,Actinobacteria and Chloroflexi were the dominant bacterial abundant in soil under different treatments at the phyla level,compared with ST and RT.STS could significantly increase the relative abundance of Proteobacteria and Acidobacteria by 2.72-10.40 percentage points,and reduce the relative abundance of Acidobacteria by 6.98-11.10 percentage points.Bacillus,Acidibacter,Pseudarthrobacter,Flavobacterium,and Pirell were the dominant bacterial abundant in soil under different treatments at the genus level,compared with ST and RT.STS could significantly increase the relative abundance of Bacillus,Acidibacter,Pseudarthrobacter,and Flavobacterium by 0.52-4.13 percentage points.There were significantly positive relations between pH,SWC,SOC,and TN with the relative abundance of Bacteroidetes.There were also significantly positive relations between the SOC,CEC,TN,and AHN with the relative abundance of Bacillus,Acidibacter,and Pseudarthrobacter.Redundancy analysis showed that the SOC,pH,SWC,CEC,and available potassium(AK)were the main environmental factors affecting the structure of the soil bacterial community.The PICRUSt functional prediction results showed that the metabolism is the main primary function of the bacterial community in irrigated sierozem.In conclusion,subsoiling with the return of maize straw is the best measure to improve the soil fertility,bacterial diversity and improve the microenvironment of farmland.