有机肥和秸秆还田对土壤表面电化学性质的影响

    Effect of organic fertilizer and straw returning on soil surface electrochemical characteristics

    • 摘要: 研究长期施用有机肥和秸秆还田对土壤表面电化学性质的影响机制,明确影响土壤表面电化学性质的关键因素,可为耕地肥力的提升提供理论依据。该研究依托于运城市水头试验基地始于2007年的长期定位试验,设置单施化肥(F)、有机肥+化肥(MF)、秸秆还田+化肥(SF)以及有机肥+秸秆还田+化肥(MSF)4个处理,采用物质表面性质联合测定法测定表面电荷数量、比表面积、表面电荷密度、表面电场强度以及表面电位等土壤表面电化学性质,同时分析土壤机械组成、有机碳组分(可溶性有机碳、颗粒态有机碳以及矿物质结合态腐殖质、富里酸和胡敏酸)和矿物质结合态腐殖质的结构特征。结果表明:与F处理相比,有机肥和秸秆还田处理(MF、SF和MSF)显著提高各土壤表面电化学性质属性(P<0.05),其中以MSF处理最高,分别为17.07 cmol/kg、67.02 m2/g、0.25 c/m2、5.12×108 V/m和-91.14 mV。与F处理相比,有机肥和秸秆还田处理(MF、SF和MSF)显著提高土壤总有机碳和各有机碳组分的含量以及胡敏酸/富里酸的比值(P < 0.05),其中以MSF处理最高;同时,MSF处理显著降低了矿物质结合态腐殖质的E4/E6和ΔlgK(P < 0.05),并提高了腐殖质的C=O/C(O)N基团的相对含量。土壤总有机碳、各有机碳组分、黏粒含量以及胡敏酸/富里酸的比值与各土壤表面电化学性质属性呈显著的正相关关系(P < 0.05);其中以矿物质结合态腐殖质、黏粒含量以及胡敏酸/富里酸的比值对土壤表面电化学性质的影响最为突出,解释率分别为67.0%、5.9%和4.9%,并且矿物质结合态腐殖质的E4/E6和ΔlgK以及C=O/C(O)N基团与土壤表面电化学性质密切相关(P < 0.05)。综上所述,长期有机肥和秸秆还田的培肥措施可通过有机碳组分以及腐殖质化学结构来调控土壤表面电化学性质。

       

      Abstract: Minute particles within the soil can normally possess charges and predominantly concentrate on the soil colloids. These charges on the soil surface can contribute to a variety of physical, chemical, and physiochemical characteristics of the soil. Key property parameters of soil colloidal particles can include the surface potential, surface charge density, surface electric field intensity, specific surface area, and surface charge number. The objective of this study was to investigate the impacts of prolonged utilization of organic fertilizer and straw on these electrochemical characteristics of the soil surface. Furthermore, the primary influencing factors were determined to enhance the fertility of arable land. A long-term experiment was conducted at the Shuitou experimental base in Yuncheng City, Shanxi Province since in 2007. Four treatments were set as the exclusive application of chemical fertilizer (F), a combination of organic and chemical fertilizer (MF), the integration of straw returning with chemical fertilizer (SF), and a comprehensive application of organic fertilizer, straw returning, and chemical fertilizer (MSF). The electrochemical properties of the soil surface were examined, including surface potential, surface charge density, surface electric field intensity, specific surface area, and surface charge number. Additionally, organic carbon fractions were also analyzed, such as soluble organic carbon, particulate organic carbon, mineral-associated humus, fulvic acid, and humic acid. Furthermore, the investigation was conducted on the structural characteristics of mineral-associated humus. The results indicated that the application of organic fertilizer and straw returning treatments (MF, SF, and MSF) was substantially enhanced the electrochemical characteristics of the soil surface, compared with the F treatment (P<0.05). Among them, the MSF treatment exhibited the highest values, with the respective measurements of 17.07 cmol/kg, 67.02 m2/g, 0.25 c/m2, 5.12×108 V/m, and -91.14 mV, respectively. Compared with the F treatment, the MF, SF, and MSF treatments were significantly enhanced the quantities of total soil organic carbon and organic carbon fractions, including the soluble organic carbon, particulate organic carbon, mineral-associated humus, fulvic acid, and humic acid. Additionally, there was also an increase in the ratio of humic acid to fulvic acid (P<0.05). Specifically, the MSF treatment exhibited the highest contents and ratio, with the values of 21.5, 0.1, 12.1, 5.5, 3.3, 2.2 g/kg and 1.5. Meanwhile, the organic fertilizer and straw returning treatments were resulted in the a significant reduction in the E4/E6 and △lgK values of mineral-associated humus (P<0.05). There was the an increase in the relative abundance of C=O/C(O)N group within the mineral-associated humus. The comprehensive analysis revealed that there was the a significant positive correlation between soil surface electrochemical characteristics and various factors, including the total soil organic carbon, organic carbon fractions, clay content, and the ratio of humic acid to fulvic acid. Notably, there were the most substantial influences on the soil surface electrochemical characteristics by the mineral-associated humus, clay content, and the ratio of humic acid to fulvic acid, with the interpretation rates of 67.0%, 5.9%, and 4.8% respectively. And the E4/E6, △lgK, and C=O/C(O)N groups of humus were strongly associated with the soil surface electrochemical characteristics. In summary, the prolonged use of organic fertilizer and straw were substantially enhanced the electrochemical properties of the soil surface, in terms of the soil organic carbon fraction and the structural characteristics of humus. Consequently, these findings can also provide the theoretical foundation for the microscopic and macroscopic processes in soil.

       

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