有机肥中重金属对菜田土壤微生物群落代谢的影响

基于慈溪掌起镇的蔬菜施肥试验,结合常规理化分析和Micro RESPTM方法,在2年4次施肥后,分析不施肥(CK)、重金属达标商品有机肥(T1)和Pb-As-Cu-Zn添加有机肥(T2)施用土壤的基本理化性质、重金属累积以及微生物群落代谢特征,探讨重金属对施用有机肥土壤微生物群落代谢特征的影响。结果表明,T1和T2显著提高了旱地蔬菜轮作土壤有机质和部分养分含量,且二者无显著差异。但从重金属含量上看,T2土壤Cu、Zn全量以及有效态Cu、Zn、As含量显著高于T1和CK土壤。基于Micro RESPTM的微生物群落代谢特征分析指出,与CK相比,T1显著促进了土壤基础呼吸作用和微生物代谢功能多样性,T2却无类似的促进效果,可见T2土壤Cu、Zn和有效态As含量的大幅增加削弱了有机肥中有机质等养分对土壤微生物的促进作用。主成分和聚类分析进一步表明,T1与T2土壤的微生物群落水平生理指纹图谱(CLPP)存在明显差异,T2土壤中重金属及其有效性的增加诱导柠檬酸、苹果酸和草酸等羧酸代谢利用增强。综上,畜禽粪便有机肥对菜田土壤微生物群落代谢的作用同时受到有机肥本身及其残留重金属的影响,有机肥中过高的重金属残留会改变有机肥养分对土壤微生物代谢的影响。

Effects of heavy metal within organic fertilizers on the microbial community metabolic profile of a vegetable soil after land application

This study investigated the effect of heavy metals in organic fertilizer on the metabolic characteristics of soil microbial community on the basis of a vegetable fertilization experiment, which was carried out in Zhangqi Town, Cixi City. Vegetable planting and fertilization were performed twice each year. Three fertilization treatments were included:CK treatment with no fertilizer; T1 treatment with a manure fertilizer having heavy metal levels within the safe limit set by China; T2 treatment with a manure fertilizer having an increased level of Pb, As, Cu and Zn. After two years, soil physic-chemical properties, soil heavy metals and metabolic characteristic of soil microbial community were measured by using both conventional soil analysis method and MicroRESP^TM technology. Results indicated that both T1 and T2 significantly increased the soil content of organic matter, available phosphorus and available potassium. Although there is insignificant difference in soil physic-chemical properties between T1 and T2, T2 had significantly higher contents of total Cu, total Zn, available Cu, available Zn and available As in soil. Microbial community metabolic profile analysis based on the MicroRESP^TM method showed that T1 significantly enhanced the basal respiration and the functional diversity of microbial community in soil; but T2 did not show similar enhancement. Thus, the increased level of Cu, Zn and available As in T2 soil might reduce the positive effect of nutrients within manure on soil microbial community. Principle component analysis and cluster analysis results further showed that the community level physiological profile(CLPP) in T1 soil was apparently different from that in T2 soil. The highly accumulated heavy metals and their increased availability in T2 soil enhanced the utilization of citric acid, malic acid and oxalic acid in soil. In conclusion, the effect of manure fertilizer on the metabolic function of soil microbial community was related to both manure nutrients and its residual heavy metal. The application of manure fertilizer with excessive residual heavy metal would change the effect of manure nutrients on soil microbial community.