Abstract

The extractable fractions of organic matter (OM) differing in their mobility—water-extractable organic matter, labile humic substances, and humic substances—have been isolated from different-sized aggregates of a typical chernozem (Haplic Chernozem (Loamic, Pachic)). The first two fractions characterize the active OM pool, and the latter fraction characterizes the slow OM pool. Overall, the extractable OM fractions make it possible to assess the content and qualitative composition of the active and slow OM pools and, in an indirect manner, of the passive OM pool. The content of dissolved organic carbon in the extracts is used to quantify the yield of fractions, and the spectral characteristics of light absorption in the ultraviolet and visible ranges attest to their qualitative composition. The main attention is focused on the OM recovery in the chernozems after an extreme regime (permanent tilled fallow) and on the differences in the OM of soil aggregates in dependence on their size. A large part of plant residues entering the soil during the recovery of the chernozem after the extreme conditions of tilled fallow is fixed in the passive OM pool. The qualitative composition of active pools is restored much faster than their quantity typical of the undisturbed cenoses. The optical descriptors E₂/E₃ of labile humic substances and E₄/E₆ of humic substances significantly depends on the size of aggregates.

中文翻译：

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长期野外实验中典型黑藜中可萃取有机物组分的光学性质

摘要

有机物（OM）的可提取馏分的迁移率各不相同-水溶性有机物，不稳定的腐殖质和腐殖质-已从典型黑藜（Haplic Chernozem（Loamic，Pachic））的不同大小的聚集物中分离得到。前两个部分描述了活动的OM池，后面的部分描述了慢速OM池。总体而言，可提取的OM馏分可以评估主动和慢速OM池以及以间接方式评估被动OM池的含量和定性组成。提取物中溶解的有机碳的含量用于量化馏分的产率，并且紫外和可见光范围内的光吸收光谱特征证明了它们的定性组成。主要关注点集中在极端条件（永久耕作休耕后）黑钙土的OM恢复上，以及取决于土壤聚集体大小的OM差异。在耕作休耕的极端条件之后，在黑钙土恢复期间，大部分植物残渣进入土壤，这些残留物固定在被动式OM池中。活动池的定性组成要比未受干扰的人口普查的数量恢复得快得多。光学描述符不稳定的腐殖质的E ₂ / E ₃和腐殖质的E ₄ / E ₆很大程度上取决于聚集体的大小。