Ground data on spectral characteristics of Jordan's soils remain sparse, which makes the interpretation of remote sensing datasets challenging. These are, however, very useful for predicting soil properties and agricultural suitability. Previous studies have shown that soil colours correlate well with degrees of weathering intensity, as indicated by magnetic parameters and dithionite‐extractable iron (Fed) contents along a climosequence in northern Jordan. This study enlarges the database by the results of 160 bulk samples that were collected systematically from the soil surface at 40 locations. In addition to soil colour and contents of Fed, we explore mean soil reflectance spectra (MSRS) measured by analytical spectral devices (ASD) and analyse the morphological conditions of the spectra referring to the effects of iron oxides on spectral behaviours. Results show a high correlation of spectral behaviours and colour variations with Fe oxides, and no correlation with soil organic carbon Corg. The influence of the Fe oxide contents is clearly apparent in the visible range (VIS). The presence of CaCO3 increases the reflectance in all spectral ranges. Six soil groups (Gr. I ‐ Gr. VI) were discerned qualitatively and quantitatively in the study area, which largely mirror the intensity of red colour expressed by redness indices.

中文翻译：

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约旦北部表层土壤光谱特征、氧化铁和颜色之间的关系

关于约旦土壤光谱特征的地面数据仍然稀少，这使得遥感数据集的解释具有挑战性。然而，这些对于预测土壤特性和农业适宜性非常有用。先前的研究表明，土壤颜色与风化强度的程度密切相关，如磁参数和约旦北部气候序列沿线的连二亚硫酸盐可萃取铁 (Fed) 含量所表明的那样。本研究通过从 40 个地点的土壤表面系统收集的 160 个散装样品的结果扩大了数据库。除了土壤颜色和美联储的内容，我们探索了由分析光谱设备 (ASD) 测量的平均土壤反射光谱 (MSRS)，并分析了光谱的形态条件，涉及氧化铁对光谱行为的影响。结果显示光谱行为和颜色变化与 Fe 氧化物高度相关，与土壤有机碳 Corg 没有相关性。在可见光范围 (VIS) 中，Fe 氧化物含量的影响非常明显。CaCO3 的存在增加了所有光谱范围内的反射率。在研究区定性和定量地识别出六个土壤组 (Gr. I - Gr. VI)，这在很大程度上反映了红色指数表示的红色强度。在可见光范围 (VIS) 中，Fe 氧化物含量的影响非常明显。CaCO3 的存在增加了所有光谱范围内的反射率。在研究区定性和定量地识别出六个土壤组 (Gr. I - Gr. VI)，这在很大程度上反映了红色指数表示的红色强度。在可见光范围 (VIS) 中，Fe 氧化物含量的影响非常明显。CaCO3 的存在增加了所有光谱范围内的反射率。在研究区定性和定量地识别出六个土壤组 (Gr. I - Gr. VI)，这在很大程度上反映了红色指数表示的红色强度。