Abstract The soil mineralogical constitution directly influences its chemical, physical and hydraulic characteristics. Although very important, it is still rarely used for decision-making in agriculture, mainly due to the complexity and cost of standard analyzes. In this sense, the middle infrared spectroscopy (mid-IR, 4000 to 400 cm−1) has great potential to obtain soil mineralogical information quickly and accurately. Nevertheless, some soil constituents can severely influence the spectra and produce misinterpretations. In this research, we aim to detect changes in the mid-IR spectra caused by water, iron forms and organic matter (OM), and to relate soil attributes to laboratory spectra and remote sensing simulated spectral bands. The research area is located in Sao Paulo State, Brazil, where seventeen soil samples were collected. The reflectance intensities, shapes and absorption features of the mid-IR spectra before and after the removal of OM and iron forms and the addition of water were described. Soil attributes, such as kaolinite, gibbsite, 2:1 minerals among others were correlated with the mid-IR spectra and simulated ASTER spectral bands by Pearson's analysis, to verify its potential on mineralogical evaluation. The description of mid-IR revealed that the removal of the OM from the soil samples decreased the reflectance intensities between 4000 and 2000 cm−1. Iron forms mainly influence the 3250 – 1200 cm−1 spectral range and mask the spectral features of other minerals as well. The addition of water masked several absorption features and decreased the reflectance intensities from 3700 to 2700 cm−1. High correlation coefficients were obtained between soil attributes and ASTER simulated spectral bands, which allowed the selection of potential spectral regions for future satellite sensors: 2760 – 2500 cm−1 (3600 – 4000 nm), 2150 – 1875 cm−1 (4600 – 5300 nm), and 840 – 740 cm−1 (11900 – 3500 nm).

中文翻译：

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土壤中红外光谱中水、有机质和铁形式的影响：从实验室到卫星模拟数据的评估

摘要 土壤矿物组成直接影响其化学、物理和水力特性。尽管非常重要，但它仍然很少用于农业决策，主要是由于标准分析的复杂性和成本。从这个意义上说，中红外光谱（mid-IR，4000~400 cm-1）具有快速准确获取土壤矿物学信息的巨大潜力。然而，一些土壤成分会严重影响光谱并产生误解。在这项研究中，我们旨在检测由水、铁形式和有机物质 (OM) 引起的中红外光谱变化，并将土壤属性与实验室光谱和遥感模拟光谱带联系起来。研究区位于巴西圣保罗州，在那里采集了 17 个土壤样本。描述了去除 OM 和铁形式以及加水前后中红外光谱的反射强度、形状和吸收特征。土壤属性，如高岭石、三水铝石、2:1 矿物等，通过 Pearson 分析与中红外光谱和模拟 ASTER 光谱带相关联，以验证其在矿物学评估中的潜力。中红外的描述表明，从土壤样品中去除 OM 会降低 4000 到 2000 cm-1 之间的反射强度。铁的形态主要影响 3250 – 1200 cm-1 的光谱范围并掩盖其他矿物的光谱特征。水的加入掩盖了几个吸收特征并将反射强度从 3700 降低到 2700 cm-1。