The fragipan subsoil horizon can be a significant limitation to land use and management because of its ability to perch water, restrict root growth, and reduce available water storage. Recognition of the presence of a fragipan is used to describe some diagnostic horizons (mollic, umbric, cambic) and to identify the limits of the particle size control section when classifying a soil according to the U.S. soil taxonomic system. While soil scientists often disagree on whether fragipan diagnostic criteria are met, they will typically agree that the horizon has fragic soil properties. To potentially improve field identification agreement, we propose that the fragipan be redefined to meet criteria more like fragic soil properties. We also propose to include some current criteria for the fragipan denoting pedogenesis, slaking, and HCl reaction. In addition, we propose a new requirement be added for redoximorphic features above the fragipan as additional evidence of its restrictive nature. Changing the fragipan's definition will do little to alter soil land use interpretations given most interpretations are based indirectly off the effects of the fragipan. Analysis of existing series indicates that our proposal should not remove series now classified with a fragipan but would eliminate some ambiguities in field identification. Whether the fragipan's spatial extent would increase or decrease is dependent on regional mapping efforts.

中文翻译：

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重新定义fragipan，以提高现场识别和土地利用的相关性

易碎裂的地下土壤层可能会严重限制土地的使用和管理，因为它具有栖息水，限制根系生长和减少可用水储量的能力。根据美国土壤分类系统对土壤进行分类时，可使用fragipan的识别来描述某些诊断范围（分子，伞形，长生的）并确定粒度控制部分的界限。尽管土壤科学家通常对是否满足fragipan诊断标准持有不同意见，但他们通常会同意地平线具有脆弱的土壤特性。为了潜在地改善田间识别协议，我们建议重新定义fragipan以符合更像易碎土壤特性的标准。我们还建议为fragipan包括一些当前的标准，以指示成岩作用，溶出和HCl反应。另外，我们建议对fragipan上方的氧化还原形态特征添加新要求，作为其限制性性质的其他证据。鉴于大多数解释都间接基于脆弱性的影响，因此更改脆弱性的定义对改变土壤土地用途的解释几乎没有作用。对现有序列的分析表明，我们的建议不应该删除现在已使用fragipan进行分类的序列，而应消除在字段识别方面的一些歧义。fragipan的空间范围是增加还是减少取决于区域制图工作。s的定义几乎不会改变土壤土地利用的解释，因为大多数解释间接地基于脆弱性的影响。对现有序列的分析表明，我们的建议不应该删除现在已使用fragipan进行分类的序列，而应消除在字段识别方面的一些歧义。fragipan的空间范围是增加还是减少取决于区域制图工作。s的定义几乎不会改变土壤土地利用的解释，因为大多数解释间接地基于脆弱性的影响。对现有序列的分析表明，我们的建议不应该删除现在已使用fragipan进行分类的序列，而应消除在字段识别方面的一些歧义。fragipan的空间范围是增加还是减少取决于区域制图工作。