The different soil organic matter (SOM) pools were isolated from the surface horizons of Haplic Chernozem in contrast variants of land use: (a) free particulate OM, (b) occluded particulate OM, (c) clay-associated OM, and (d) OM of the fraction of the Residue (Res). The features of the chemical structure studied by solid-state ¹³C NMR spectroscopy of these SOM pools in virgin Chernozem were used to demonstrate the changes that solid plant residues undergo during decomposition when they are incorporated into microaggregates. The extent of decomposition of organic materials in soils follows a continuum from fresh and partially decomposed organic materials in the discrete OM (Free and Occluded) to significantly/completely processed in the mineral-associated OM (Clay and Res).

We studied the alteration of the chemical structure in the SOM pools under the influence of the bare fallow (52-yr duration) and revealed some features of the OM quality that can contribute to the size of the structural units in the C-depleted Haplic Chernozem. It was revealed that the functioning of Haplic Chernozem in the bare fallow regime for 52 years caused sharp increases in the decomposition and aromaticity degrees of the organic matter, as well as the hydrophobicity degree. A sharp increase in its hydrophobicity indicates a sharp decrease in its adhesive ability. This can be the reason for the almost complete destruction of one of the most valuable agronomic aggregate-size classes (2–1 mm) in the bare fallow, and the redistribution of the water-stable aggregate-size classes towards a decrease in their dimension. The decline in the aggregate size was indirectly confirmed by the decline in the average effective diameter of the clay particles (building blocks of aggregates) in the bare fallow compared to that in the steppe (382.7 vs. 443.8 nm, respectively).

从Haplic Chernozem的地表视野中分离出不同的土壤有机质（SOM）池，这与土地利用的变化形式不同：（a）游离颗粒OM，（b）颗粒颗粒OM被堵塞，（c）粘土相关的OM和（d ）残留物（Res）的分数的OM。这些SOM库在原始切尔诺泽的固态¹³ C NMR光谱研究的化学结构特征被用来证明固态植物残渣在掺入微骨料中时在分解过程中发生的变化。土壤中有机物质的分解程度是一个连续过程，从离散的OM（游离和封闭）中的新鲜和部分分解的有机物质到与矿物相关的OM（粘土和Res）中的大量/完全处理。

我们研究了裸露休耕（52年持续时间）的影响下SOM池中化学结构的变化，并揭示了OM质量的某些特征，这些特征可能有助于C贫化的Haplic黑钙石的结构单元的大小。结果表明，Haplic Chernozem在裸露的休养状态下运行了52年，导致有机物的分解度和芳香度以及疏水度急剧增加。疏水性的急剧增加表示其粘合能力的急剧下降。这可能是以下原因：几乎完全破坏了裸休耕地中最有价值的农学集料大小分类（2-1mm）之一，并且水稳定的集料大小分类朝着其尺寸减小的方向重新分布。