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中国农学通报

中国农学通报 ›› 2025, Vol. 41 ›› Issue (12): 74-79.doi: 10.11924/j.issn.1000-6850.casb2024-0628

• 资源·环境·生态·土壤 • 上一篇    下一篇

土壤矿物对烧失法测定红壤有机质含量的影响研究

刘艳1,2(), 董铭2(), 黄倩3, 梁家凤4, 王梦洁5   

  1. 1 四川省岳池县第一中学，四川广安 638300
    2 云南师范大学地理学部低纬高原环境变化云南省高校重点实验室，昆明 650500
    3 成都市彭州市宏德学校，成都 611930
    4 成都市天府实验学校北区分校，成都 610000
    5 四川省泸县第四中学，四川泸州 646101
  • 收稿日期:2024-09-28 修回日期:2025-03-03 出版日期:2025-04-25 发布日期:2025-04-24
  • 通讯作者:
    董铭，女，1976年出生，山东青岛人，副教授，硕士，研究方向：自然地理学。通信地址：650500云南省昆明市呈贡区雨花片区1号，E-mail：。
  • 作者简介:

    刘艳，女，1995年出生，四川广安人，硕士研究生，主要从事土壤环境研究。通信地址：638300 四川省广安市岳池县九龙镇银城南路518号，E-mail：。

  • 基金资助:
    国家自然科学基金项目“金沙江巧家段河流阶地记录的干热河谷形成时代研究”(41762014)

Study on Influence of Soil Minerals on Determination of Red Soil Organic Matter Content by Loss-on-ignition Method

LIU Yan1,2(), DONG Ming2(), HUANG Qian3, LIANG Jiafeng4, WANG Mengjie5   

  1. 1 No.1 Middle School of Yuechi County, Sichuan Province, Guang’an, Sichuan 638300
    2 Key Laboratory of Yunnan Universities for Changes of Low Latitude Plateau Environment, Department of Geography, Yunnan Normal University, Kunming 650500
    3 Hongde School, Pengzhou City, Chengdu 611930
    4 North Branch of Tianfu Experimental School of Chengdu, Chengdu 610000
    5 Sichuan Luxian No.4 Middle School, Luzhou, Sichuan 646101
  • Received:2024-09-28 Revised:2025-03-03 Published:2025-04-25 Online:2025-04-24

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摘要：

本研究旨在探究土壤矿物对烧失法测定土壤有机质的影响程度，选取昆明盆地东缘低有机质红壤（重铬酸钾氧化法测定有机质含量为0.49%），其土样主要由粘粒矿物、铁（氢）氧化物和碎屑矿物组成。利用X射线衍射仪、原子吸收光谱仪确定各类矿物的组成和相对含量，并对比分析烧失前后的成分变化。分析发现，土样粘粒矿物主要由三水铝石、高岭石和蒙脱石构成，铁（氢）氧化物主要为赤铁矿和针铁矿，碎屑矿物主要是石英和钠长石。经550℃烧失后粘粒矿物、铁（氢）氧化物的X射线衍射图谱发生了明显的变化，表明其在高温下发生了分解。根据各矿物在土样中的含量及理论脱水（或脱羟基）分解的烧失量估算，发现仅粘粒矿物的热分解就能够为土样贡献近90%的烧失量，铁（氢）氧化物也能贡献6%的烧失量，剩下不到4%的烧失量（即0.44%）才是有机质贡献的。这一推算结果与重铬酸钾氧化法测定的有机质含量结果十分接近。这项研究说明，粘粒矿物和铁（氢）氧化物的热分解是影响烧失法精准测定土壤有机质含量的主要原因。对于红壤样品由此引起的误差可能超过土壤有机质含量的数倍以上。

关键词: 土壤矿物, 烧失法, 红壤, 土壤有机质, X射线衍射仪, 原子吸收光谱仪

Abstract:

To explore the influence of soil minerals on the determination of soil organic matter by loss-on-ignition method, this paper selected the low organic matter red soil (the content of organic matter was 0.49% by potassium dichromate oxidation method) with relatively simple and convenient mineral composition in the eastern margin of Kunming Basin as the research object to carry out the analysis work. The soil sample was mainly composed of three parts: clay minerals, iron (hydrogen) oxides and detrital minerals. The composition and relative content of various minerals were determined by X-ray diffractometer and atomic absorption spectrometer, and the composition changes before and after burning loss were compared and analyzed. The analysis showed that clay minerals in soil samples were mainly composed of gibbsite, kaolinite and montmorillonite, iron (hydrogen) oxides were mainly hematite and goethite and detrital minerals were mainly quartz and albite. After burning at 550°C, the X-ray diffraction pattern of clay minerals and iron (hydrogen) oxides changed significantly, indicating that they were decomposed at high temperatures. According to the content of each mineral in the soil sample and their theoretical dehydration (or dehydroxylation) decomposition, it was found that only the thermal decomposition of clay minerals could contribute nearly 90% of the loss on ignition of the soil sample. Iron (hydrogen) oxides could also contribute 6% of the loss-on-ignition, leaving less than 4% of the loss-on-ignition (0.44%) contributed by organic matter. This calculation result was very close to the organic matter content determined by the potassium dichromate oxidation method. This study showed that the thermal decomposition of clay minerals and iron (hydrogen) oxygen compounds was the main reason that affected the accurate determination of soil organic matter content by the loss-on-ignition method. For red soil samples, the resulting error may be more than several times that of soil organic matter content.

Key words: soil minerals, loss-on-ignition method, red soil, soil organic matter, X-ray diffractometer, atomic absorption spectrometer