Abstract：
Information about impacts of long-term biosolids application on soil microbial populations and functional groups and N cycling is important for evaluating soil health and agroecosystem sustainability under long-term biosolids application. Mine spoil plots received annual biosolids application from 1973 to 2010 at low (16.8 Mg ha-1 yr-1), medium (33.6 Mg ha-1 yr-1), and high rates (67.2 Mg ha-1 yr-1). A no-biosolids control received chemical fertilizer at the agronomic rate. Soil samples were collected in three seasons per year spanning 2003-2005 for measuring soil moisture, pH, soil organic C (SOC), total and extractable heavy metals (Cd, Cu, Ni, Zn), NO3-, N mineralization potential (NMP), microbial biomass C (MBC), and populations of three N-cycling bacteria (NCB) groups: ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and denitrifying bacteria (DNB). Soil samples were collected again in 2008 and 2010 for quantifying total and extractable heavy metals, and in 2018 (eight years after biosolids applications ended) for measuring SOC, MBC, NMP, and microbial respiration. During 2003-2005, mean MBC was 315, 554, 794, and 1001 mg kg-1 in the control, low, medium, and high biosolids treatments, respectively. Populations of NCB did not differ among treatments. Biosolids application increased total and extractable metal concentrations but the effect of biosolids rates were much lower on extractable than total concentrations. Soil extractable Cd and Cu concentrations decreased from medium to high applications, likely due to complexing with biosolids organic matter. Partial least squares regression analysis identified a strong positive effect on MBC of SOC and a weak negative effect of Cu, explaining the strong net positive effect of biosolids on MBC. In 2018, the medium and high biosolids treatments maintained higher SOC, MBC, NMP, and microbial respiration than the control. This study provided further evidence that long-term biosolids application has positive effects on soil microbes that persist for years after ending application.
摘要：
有关长期生物固体施用对土壤微生物种群和官能团以及氮循环的影响的信息对于评估长期生物固体施用下的土壤健康和农业生态系统可持续性非常重要。从1973年到2010年，矿渣地块每年都以较低的速度（16.8Mgha-1yr-1）获得生物固体应用，中等（33.6Mgha-1yr-1），和高利率（67.2Mgha-1yr-1）。无生物固体对照以农艺速率接受化肥。在2003-2005年期间，每年三个季节收集土壤样本，用于测量土壤湿度，pH值,土壤有机碳(SOC)，总重金属和可提取重金属(Cd，Cu,Ni,Zn),NO3-,N矿化潜力（NMP），微生物生物量C（MBC），和三个氮循环细菌（NCB）组的种群：氨氧化细菌（AOB），亚硝酸盐氧化细菌（NOB），和反硝化细菌（DNB）。在2008年和2010年再次收集了土壤样品，用于量化总重金属和可提取重金属，在2018年(生物固体应用结束八年后)测量SOC，MBC,NMP,和微生物呼吸。在2003-2005年期间，对照组的平均MBC为315、554、794和1001mgkg-1，低,中等,和高生物固体处理，分别。NCB的人群在治疗之间没有差异。生物固体的应用增加了总的和可提取的金属浓度，但生物固体速率对可提取的影响远低于总浓度。土壤可提取的Cd和Cu浓度从中到高施用降低，可能是由于与生物固体有机物质络合。偏最小二乘回归分析确定了对SOC的MBC有较强的正效应和Cu的弱负效应,解释了生物固体对MBC的强净正效应。2018年，中高生物固体处理保持较高的SOC，MBC,NMP,和微生物呼吸比对照。这项研究提供了进一步的证据，表明长期的生物固体施用对土壤微生物有积极的影响，这种影响在结束施用后持续数年。
