连续施用不同量污泥堆肥对土壤氮组分及δ15N的影响

摘要

In order to provide a theoretical basis for fertilizing and improving sandy fluvo-aquic soil quality,soil total nitrogen,content of different fractions of active organic nitrogen and soil δ15N values were determined after continuous application of nonhazardous composted sewage sludge (SW) in this study.Four-year field experiment was conducted in a wheat-maize rotation crop field during 2013-2016 in Henan province,China.Based on different fractions of soil active organic nitrogen and stable nitrogen isotope technology,and the response of soil physical and chemical properties,we studied the response of soil active organic nitrogen and soil δ15N values to composted sewage sludge.The results were that 1) Continuous application of SW significantly raised the content of soil carbon and nitrogen,with 265.83％ and 284.31％ increase,respectively,by the 45 t · hm-2 SW treatment in comparison with the control group (CK).The SW treatments significantly enhanced the active organic nitrogen component content and the particulate organic nitrogen (PON) by 104.57％-280.91％.The content of active nitrogen components in the treatment were presented as particulate organic nitrogen (PON)＞light fraction organic matter nitrogen (LFON)＞dissolved organic nitrogen (DON)＞soil microbial biomass nitrogen (SMBN).The allocation of PON/TN and SMBN/TN increased,and the allocation of LFON/TN and DON/TN significantly decreased withthe increasing application of SW,which resulted in decrease of the total distribution proportion of active nitrogen,indicating that the 45 t · hm-2 SW treatment contained enough stable organic nitrogen components for the accumulation of organic nitrogen.2) Soil amended with SW significantly reduced soil δ15N values.The pathway analysis and the principal components analysis revealed that the rate of SW had a significantly effect on the soil δ15N values and soil nitrogen content,while correlation analysis showed that soil δ15N values had the strong relationship with the soil TN,PON and LFON contents,which indicated that the δ15N could reflected the effect of soil improvement with the SW.3) Redundancy analysis further revealed that soil pH,soil moisture and soil fertility had significant effects on the content of soil active organic nitrogen fractions and their δ15N values.Soil pH and soil integrated fertility index (IFI) were the most significant factors influencing soil active organic nitrogen fractions and their δ15N values (P＜0.05),and they could explain 48.2％ and 17.5％ of the variation respectively,through the redundancy analysis.The results showed that four years of SW application,particularly the 45 t · hm-2 SW treatment,could significantly increase the soil nitrogen content and nitrogen quality,and thus improved the soil fertility.δ15N could be used as a good indicator for the dynamic changes of soil nitrogen and soil quality after SW application.%为探明连续施用无害化污泥堆肥(以下简称堆肥)对土壤全氮(TN)、不同活性氮组分含量及土壤δ15N的影响,为堆肥改良和培肥沙质潮土提供理论依据.本研究以河南省小麦-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,基于不同土壤活性氮组分分组技术和氮稳定性同位素技术,分析土壤活性氮组分和土壤δ15N对堆肥施入量的响应特征.结果表明,1)连续施用堆肥显著增加了土壤碳氮含量,随施入量增加而显著增加,其中施堆肥量达45 t·hm-2时效果最为显著,较单施化肥(CK)处理分别增加了265.83％和284.31％(P＜0.05).施用堆肥可以提高活性有机氮组分含量,其中颗粒态有机氮(PON)增加了104.57％～280.91％;处理间各活性氮组分含量呈现:颗粒态有机氮(PON)＞轻组有机氮(LFON)＞水溶性有机氮(DON)＞微生物量氮(SMBN).增加堆肥施人量提高了PON/TN和SMBN/TN分配比例,显著降低了LFON/TN和DON/TN分配比例(P＜0.05),从而降低土壤活性氮组分在全氮中的分配比例,说明高堆肥施用量促进土壤氮素以稳定态有机氮形式储存,有利于土壤氮素的累积.2)施用堆肥显著降低了土壤δ15N,通径分析和主成分分析表明,土壤δ15N与土壤氮含量受堆肥施入量影响显著;相关性分析表明,δ15N与土壤TN、PON和LFON含量呈显著相关性,表明土壤δ15N变化特征可指示土壤氮组分受堆肥处理作用的响应.3)冗余分析表明,土壤pH、土壤水分及土壤肥力水平(IFI)均会对土壤氮组分含量、活性氮组分分配比例及δ15N产生影响,其中对土壤IFI和土壤pH作用显著(P＜0.05),解释率分别达48.2％和17.5％.综上可知,施用堆肥提高了土壤有机物含量,施用量达45 t· hm-2时,显著提高了土壤氮储量和活性氮组分含量,对沙质潮土的培肥效果明显,同时,土壤稳定性同位素δ15N变化特征可作为堆肥对沙质土壤质量提升效果的指示指标.