Fernández José M, Hernández Diana, Plaza César, Polo Alfredo
Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Científicas, Serrano 115 dpdo., 28006 Madrid, Spain.
Sci Total Environ. 2007 May 25;378(1-2):75-80. doi: 10.1016/j.scitotenv.2007.01.008. Epub 2007 Feb 20.
The cumulative and residual effects of composted and thermally-dried sewage sludge (CSS and TSS, respectively) on soil organic matter and its humified fraction were evaluated in a field experiment under Mediterranean conditions. The experimental design included soil plots either unamended (control) or amended with mineral fertilizer, CSS and TSS at rates of 20 and 80 t ha(-)(1). After the first year of sewage sludge application, each plot was divided into two subplots. In one subplot group, no additional application of SS was made in the following 3 years, and the residual effect of the first applications was evaluated. In the second subplot group, the cumulative effect of sludge amendments was evaluated by applying CSS and TSS also in the following three consecutive years. Nine months after the yearly sludge and mineral fertilizer applications, surface soil samples from control and amended soils were collected and analyzed for total organic C (TOC), total extractable C (TEC), and humified C fractions, both humic acid C (HAC) and fulvic acid C (FAC) fractions. Compared with the control and mineral treatments, which showed similar results, the repeated application to soil of TSS, and specially CSS, induced an increase on the content of the organic fractions examined, as well as HA percentage (%HA=HAC/TOC) and degree of polymerisation (DP=HAC/FAC). In the residual experiment, the TOC, TEC, HAC and FAC content of soils amended once with CSS and TSS decreased slightly when increasing the time from the amendment, whereas the %HA and DP tended to increase. Further, three years after the sludge applications, with respect to the control soil, the soils amended once with CSS exhibited similar TOC, TEC, and FAC content, and slightly larger HAC content, %HA and DP; whereas those amended once with TSS, featured still larger TOC, TEC, HAC content, similar FAC content, and slightly larger %HA and DP values. As a whole, the results obtained suggested that both kind of sludges contribute to improved soil organic matter levels and humified fractions, although the CSS contribution can be considered as a more efficient organic amendment than the TSS, which may present problems of maturity and degradability.
在地中海条件下的田间试验中，评估了堆肥和热干燥污水污泥（分别为CSS和TSS）对土壤有机质及其腐殖化部分的累积和残留影响。试验设计包括未改良（对照）或用矿物肥料、CSS和TSS以20和80吨公顷⁻¹的速率改良的土壤地块。在施用污水污泥的第一年之后，每个地块被分成两个子地块。在一个子地块组中，在接下来的3年中不再额外施用污泥，并评估首次施用的残留效果。在第二个子地块组中，通过在接下来的连续三年中也施用CSS和TSS来评估污泥改良的累积效果。在每年施用污泥和矿物肥料九个月后，采集对照土壤和改良土壤的表层土壤样本，分析总有机碳（TOC）、总可提取碳（TEC）以及腐殖化碳组分，即腐殖酸碳（HAC）和富里酸碳（FAC）组分。与显示出相似结果的对照和矿物处理相比，向土壤重复施用TSS，特别是CSS，导致所检测的有机组分含量增加，以及HA百分比（%HA = HAC/TOC）和聚合度（DP = HAC/FAC）增加。在残留试验中，用CSS和TSS改良一次的土壤的TOC、TEC、HAC和FAC含量随着距改良时间的增加而略有下降，而%HA和DP则趋于增加。此外，在施用污泥三年后，与对照土壤相比，用CSS改良一次的土壤表现出相似的TOC、TEC和FAC含量，以及略高的HAC含量、%HA和DP；而用TSS改良一次的土壤，其TOC、TEC、HAC含量仍然更高，FAC含量相似，%HA和DP值略高。总体而言，所获得的结果表明，两种污泥都有助于提高土壤有机质水平和腐殖化部分，尽管CSS的贡献可被视为比TSS更有效的有机改良剂，TSS可能存在成熟度和降解性问题。
