长期施肥黑土phoD微生物群落特征及其对有机磷组分的影响

Characteristics of phoD-Harboring Microbial Communities Under Long-Term Fertilization and Its Effects on Organic Phosphorus Fractions in Black Soil

【目的】通过分析长期施肥对黑土有机磷组分和phoD微生物群落特征的影响,探究土壤有机磷组分对微生物关键群落特征的响应,为黑土磷高效利用和制定科学的施肥策略提供理论依据。【方法】依托吉林省公主岭市始于1989年的黑土长期施肥试验,选取5个施肥处理:不施肥(CK)、施氮钾肥(NK)、氮磷钾肥(NPK)、氮磷钾+秸秆(NPKS)和氮磷钾+有机肥(NPKM)。以2018年采集的0—20 cm土层的土壤样品为研究对象,采用化学连续浸提法,定量分析不同活性的有机磷组分;采用Illumina Miseq高通量测序平台和实时荧光定量(Real-time PCR)技术,定性和定量分析土壤中phoD微生物群落特征;通过相关分析及方差分解分析,综合探究phoD微生物群落组成、土壤有机磷组分与土壤性质之间的关系。【结果】(1)除NPKM处理外,各施肥处理间总有机磷含量无显著差异,但有机磷组分含量及其占总有机磷的比例差异较大。与CK相比,NK与NPKM处理均显著增加了活性有机磷(LOP)和中活性有机磷(MLOP)含量,NK处理LOP与MLOP分别增加了108.7%和27.5%;NPKM处理LOP与MLOP分别增加了446.6%和38.1%。与NPK处理相比,NPKS处理下LOP和MLOP含量显著降低了57.7%和24.0%。(2)化肥配施有机物料(NPKS、NPKM)改变了phoD微生物的群落组成,而对其多样性无显著影响。NPKS处理显著提高Pseudomonas丰度;NPKM处理显著提高Gemmatimonas的丰度。同时,NPKS处理还显著提高了phoD基因的绝对丰度和碱性磷酸酶(alkaline phosphatase,ALP)活性。(3)相关性分析表明,phoD微生物群落组成与LOP和MLOP之间有显著的关系。方差分解分析表明,对有机磷组分含量和比例变化而言,phoD微生物群落组成单独解释率分别为12.1%和10.2%,而其与ALP活性共同的解释率分别为58.5%和58.7%,与有机碳(SOC)共同的解释率分别高达67.5%和64.7%。由此可见,群落组成与土壤性质(ALP活性、SOC)共同影响有机磷组分,且影响效果优于单独指标。【结论】长期施肥改变了phoD微生物群落组成,其与ALP活性、与SOC分别共同解释有机磷组分的变化。化肥配施秸秆通过改善phoD微生物群落特征,显著提高碱性磷酸酶活性,从而促进有机磷矿化,提高黑土磷素的利用效率。

【Objective】The effects of long-term fertilization on the organic phosphorus(P_(o))fractions and phoD-harboring microbial community characteristics in black soil were analyzed,as well as the response of P_(o) fractions to key microbial community characteristics was explored,so as to provide a theoretical basis for the efficient utilization of phosphorus in black soil and for the establishment of scientific fertilization strategies.【Method】Based on the long-term fertilization experiment started in 1989 in black soil,five fertilization treatments were selected:no-fertilizer(CK),nitrogen and potassium fertilizers(NK),nitrogen,phosphorus and potassium fertilizers(NPK),nitrogen,phosphorus and potassium fertilizers plus straw return(NPKS),and nitrogen and phosphorus and potassium fertilizers plus manure(NPKM).Soil samples collected from the 0-20 cm in 2018 were used for the study.Chemical sequential fractionation was performed to quantitatively analyze the P_(o) fractions.Illumina Miseq high-throughput sequencing platform and real-time PCR technology were used to qualitatively and quantitatively analyze the characteristics of phoD-harboring microbial community in soil.The relationships among phoD-harboring microbial community composition,P_(o) fractions and soil properties were comprehensively explored through correlation and variance partitioning analysis.【Result】(1)Except for NPKM treatment,there was no significant difference in total P_(o) content among different fertilization treatments,while there was a significant difference in the content and proportion in the total P_(o) of P_(o) fractions.Compared with CK,the content of labile P_(o)(LOP)and moderately labile P_(o)(MLOP)were significantly increased under NK and NPKM treatment,and the content of LOP and MLOP under NK increased by 108.7%and 27.5%,respectively,whereas that under NPKM treatment increased by 446.6%and 38.1%,respectively.Compared with the NPK treatment,the content of LOP and MLOP under the NPKS treatment were significantly reduced by 57.7%and 24.0%,respectively.(2)The fertilizer application with organic materials(NPKS and NPKM)changed the community composition of phoD-haboring microorganisms,but had no effect on their diversities.The NPKS treatment significantly increased the abundance of Pseudomonas,and the NPKM treatment significantly increased the abundance of Gemmatimonas.Meanwhile,the NPKS treatment also significantly increased the absolute abundance of phoD genes and alkaline phosphatase(ALP)activity.(3)Correlation analysis showed that there was a significant relationship among phoD-harboring microbial community composition,LOP and MLOP.Variance partitioning analysis showed that phoD-harboring microbial community composition individually explained 12.1%and 10.2%of the variations in the content and proportion of P_(o) fractions,whereas that were 58.5%and 58.7%jointly with ALP activity,and 67.5%and 64.7%jointly with soil organic matter(SOC),respectively.It could be seen that community composition and soil properties(ALP activity,SOC)jointly affected organic phosphorus components,and their impact effect was better than individual indicators.【Conclusion】Long-term fertilization applications altered phoD-harboring microbial community composition,which interacted with ALP activity and SOC explained changes in P_(o) fractions.Chemical fertilizer combined with straw could improve phoD-harboring microbial community characteristics and significantly increased alkaline phosphatase activity,thereby promoting P_(o) mineralization and improving the utilization efficiency of phosphorus in black soil.