Abstract. The quality and quantity of soil organic matter (SOM) are key elements that impact soil health and climate regulation by soils. The Rock-Eval® thermal analysis technique is becoming more commonly used, as it represents a powerful method for SOM characterization by providing insights into bulk SOM chemistry and thermal stability. In this study, we applied this technique on a large soil sample set from the first campaign (2000–2009) of the French Soil Quality Monitoring Network (RMQS – Réseau de mesures de la qualité des sols). Based on our analyses of ca. 2000 composite surface (0–30 cm) samples collected across mainland France, we observed a significant impact of land cover on both the SOM thermal stability and elemental stoichiometry. Cropland soils had a lower mean hydrogen index value (a proxy for the SOM H/C ratio) and a higher thermal stability than grasslands and forests. Regarding the oxygen index (a proxy for the SOM O/C ratio), we observed significant differences among the values for croplands, grasslands, and forests. Positive correlations of the temperature parameters with the clay content and pH highlight the protective effect of clay on organic matter as well as the impact of pH on microorganisms' mineralization activity. Surprisingly, we found weak effects of climatic parameters on the thermal stability and stoichiometry of SOM. Our data suggest that topsoil SOM is on average more oxidized and biogeochemically stable in croplands. More generally, the high number and even distribution of data across the whole French territory allow one to build a national interpretative reference for these indicators in surface soils.

中文翻译：

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法国表土中有机物的元素化学计量和 Rock-Eval® 热稳定性

摘要。土壤有机质 (SOM) 的质量和数量是影响土壤健康和土壤调节气候的关键要素。Rock-Eval® 热分析技术正变得越来越普遍，因为它代表了一种强大的 SOM 表征方法，可提供对体相 SOM 化学和热稳定性的深入了解。在这项研究中，我们将这项技术应用于法国土壤质量监测网络 (RMQS – Réseau de mesures de la qualité des sols) 第一次活动（2000-2009 年）的大型土壤样本集。根据我们对 ca 的分析。通过在法国大陆收集的 2000 个复合表面（0-30 厘米）样本，我们观察到土地覆盖对 SOM 热稳定性和元素化学计量的显着影响。与草地和森林相比，农田土壤具有较低的平均氢指数值（代表 SOM H/C 比率）和较高的热稳定性。关于氧指数（代表 SOM O/C 比率），我们观察到农田、草地和森林的值之间存在显着差异。温度参数与粘土含量和pH呈正相关，突出了粘土对有机质的保护作用以及pH对微生物矿化活性的影响。令人惊讶的是，我们发现气候参数对 SOM 的热稳定性和化学计量的影响微弱。我们的数据表明，表土 SOM 在农田中的平均氧化程度和生物地球化学稳定性更高。更普遍，