无害化污泥堆肥施用量对沙质潮土土壤活性有机碳组分的影响

无害化污泥堆肥是指城市生活污水处理过程中产生并经无害化处理最终符合《城镇污水处理厂污泥处理土地改良用泥质》(GB/T 24600—2009)土地利用标准的堆肥产品(以下简称为污泥堆肥)。以河南省小麦-玉米轮作区沙质潮土为研究对象,通过2013—2016年田间连续定位试验,研究了污泥堆肥不同施用梯度对土壤活性有机碳组分含量和活性有机碳组分在土壤有机碳(SOC)中分配比例的影响,试验处理设置为不施污泥堆肥(CK)、15 t·hm~(-2)污泥堆肥(SW1)、30 t·hm~(-2)污泥堆肥(SW2)和45 t·hm~(-2)污泥堆肥(SW3)。结果表明,较CK处理,施用污泥堆肥处理土壤SOC、全氮(TN)含量和土壤综合肥力指数(IFI)均显著升高,尤其是施用量为45 t·hm~(-2)时效果最显著(P0.05),分别增加了265.83%、284.31%和55.51%。施用污泥堆肥处理各活性碳组分含量均显著提高,且与其施用量呈正比,施用污泥堆肥处理中活性碳库各组分含量呈现:颗粒态有机碳(POC)轻组有机碳(LFOC)溶解性有机碳(DOC)微生物量碳(SMBC)。施用污泥堆肥处理促进微生物量碳分配比例(SMBC/SOC),其中SW3处理促进效果最为显著,较CK增加了256.84%(P0.05)。主成分分析结果与以上结果基本一致,表明污泥堆肥主要是通过施入量的不同影响土壤中活性碳组分及其分配比例。冗余分析结果进一步发现,土壤肥力水平、速效养分、pH和土壤水分对土壤活性碳组分含量及其分配产生影响,其中土壤综合肥力IFI指数显著影响土壤活性有机碳组分含量及其分配率(P0.05),解释率达64.3%。综上可知,连续施用4年污泥堆肥能提高沙质潮土土壤肥力,改善土壤质量,施入量为45 t·hm~(-2)时效果最为显著。

Effects of the application rate of non-hazardous composted sewage sludge on soil active organic carbon fractions of sandy fluvo-aquic soil

Non-hazardous composted sewage sludge(SW) originates from the treatment of sewage sludge and is utilized in accordance with the Control Standard of Pollutants in Agricultural Sludge(GB/T 24600-2009 China) for non-hazardous materials. This study focused on the effects of the continuous application of SW on the concentration and distribution of active organic carbon in sandy fluvo-aquic soil under a wheat-maize rotation system during 2013-2016 in Henan Province, China. Four treatments were designed as follows:applying chemical fertilizers only(CK), 15 t·hm^-2 SW(SW1), CK+30 t·hm^-2 SW(SW2), and CK+45 t·hm^-2 SW(SW3). The results showed that SW could significantly increase soil organic carbon(SOC), total nitrogen(TN) and soil integrated fertility index(IFI)(P<0.05). The SW3 treatment significantly increased SOC, TN, and IFI by 265.83%, 284.31%, and 55.51%(P<0.05). The SW application could significantly increase soil active organic carbon fractions in an amount-dependent manner in the following order:particulate organic carbon(POC) > light fraction organic carbon(LFOC) > dissolved organic carbon(DOC) > microbial biomass carbon(SMBC). The SW application could enhance the SMBC/SOC ratio, particularly the SW3 treatment, which promoted the SMBC/SOC ratio by 256.84%(P<0.05) compared with the CK treatment. However, the SW application decreased the distribution of LFOC/SOC, POC/SOC, and DOC/SOC, which indicated that SW promoted soil carbon conserved in the form of stable organic matter fractions. Consistent with the above results, the principle component analysis results showed that the influence on soil active organic carbon fractions and its distribution was dependent on the SW application amount. Redundancy analysis further revealed that soil fertility, soil available nutrients, pH and soil moisture were closely related to the content of soil active organic carbon fractions and its distribution. IFI was the most significant factor influencing soil active organic carbon fractions(P<0.05), and it could explain 64.3% of the variation through the redundancy analysis. In summary, the four years of SW application, particularly the 45 t·hm^-2 non-hazardous composted sewage sludge treatment, could significantly increase soil fertility and the content of active organic carbon, and improve the soil quality.