微咸水灌溉下微生物菌肥对盐渍土理化性质和细菌群落的影响

Effects of Microbial Fertilizer on Physicochemical Properties and Bacterial Communities of Saline Soil Under Brackish Water Irrigation

微生物菌肥改良盐渍土具有高效、绿色环保等优势,同时施加微生物菌肥是安全利用微咸水的有效方式.试验基于河套灌区中度盐渍土,以枸杞为指示植物,在微咸水灌溉条件下设置施加不同微生物菌肥量F1(4500 kg·km^(-2))、F2(7500 kg·km^(-2))、F3(10500 kg·km^(-2))和无菌肥(CK)这4个处理,研究枸杞4个关键生育期(开花期、果实膨大期、盛果期和落叶期)不同微生物菌肥施用量对土壤盐基离子、水分、pH值、养分和细菌群落的影响.结果表明,相较CK,F1仅显著降低了前2个生育期Na+含量(P<0.05),而F2和F3均显著降低全生育期Na+含量(P<0.05),平均降低33.66%和57.98%;F3显著提高了全生育期的土壤含水率(MC)、有机质(OM)、碱解氮(AN)和速效磷(AP)含量(P<0.05).枸杞生育旺盛期,F3的Shannon指数较CK提高了4.41%;土壤优势菌门为变形菌门、拟杆菌门和放线菌门,优势菌属为鞘脂单胞菌属和假单胞菌属.研究区细菌群落最丰富的功能是化学异养和需氧化学异养,平均相对丰度分别为15.07%和13.16%,施肥处理增加土壤细菌的几丁质分解功能和叶绿体功能,其中F2的增加程度最高.典型相关分析(CCA)结果表明,MC、Na+和OM是影响细菌群落组成的重要因素,相关性热图显示MC和浮霉菌门呈显著正相关(P<0.01),Gp6和AN呈显著正相关(P<0.01).相较CK,F3处理在生育期内增加了Gp6的相对丰度,优化了群落结构.综上,微咸水灌溉下施用10500 kg·km^(-2)的微生物菌肥(F3处理)可显著降低土壤盐分、提高养分和改善土壤细菌群落结构多样性,利于微咸水安全利用和维护土壤生态健康.

The improvement of saline soil with microbial fertilizer has numerous advantages including high efficiency,green environmental protection,etc.At the same time,applying microbial fertilizer is an effective way to safely use brackish water.Based on the moderately saline soil in the Hetao irrigation area,four treatments of F1(4500 kg·km^(-2)),F2(7500 kg·km^(-2)),F3(10500 kg·km^(-2)),and CK without microbial fertilizer were applied under brackish water irrigation using Lycium barbarum as the indicator plants.The aim was to study the effects of different microbial fertilizer application rates on soil ions,soil moisture content,pH value,nutrients,and bacterial community in four key growth stages of L.barbarum(flowering stage,fruit expansion stage,full fruit stage,and deciduous stage).The results showed that,compared with that in CK,F1 only significantly decreased Na+content in the first two growth stages(P<0.05),whereas F2 and F3 significantly decreased Na+content in the whole growth period(P<0.05),with an average reduction of 33.66%and 57.98%,respectively,and F3 significantly increased soil moisture content(MC),organic matter(OM),alkaline hydrolysis nitrogen(AN),and available phosphorus(AP)contents(P<0.05)during the whole growth period.In the flourishing period of L.barbarum,the Shannon index of F3 increased by 4.41%compared with that of CK.The dominant bacterial phyla in the soil were Proteobacteria,Bacteroidetes,and Actinobacteria,and the dominant bacterial genera were Sphingomonas and Pseudomonas.The most abundant functions of bacterial communities in the study area were chemoheterotrophy and aerobic chemoheterotrophy,with an average relative abundance of 15.07%and 13.16%,respectively.The application of microbial fertilizer increased the chitinolysis function and chloroplast functions of soil bacteria,which F2 increased to the highest degree.Canonical correlation analysis(CCA)showed that MC,Na+,and OM were important factors affecting the composition of the bacterial community.The correlation heat map showed that MC was positively correlated with Planctomycetes(P<0.01),and Gp6 was positively correlated with AN(P<0.01).Compared with that in CK,the F3 treatment increased the relative abundance of Gp6 and optimized the community structure during the growth period.In conclusion,the application of 10500 kg·km^(-2)microbial fertilizer(F3 treatment)under brackish water irrigation could significantly reduce soil salinity,increase nutrients,and improve the diversity of the soil bacterial community structure,which is conducive to the safe utilization of brackish water and the maintenance of soil ecological health.