Long‐term applications of inorganic and organic fertilizers have great effects on soil characteristics and crop yields. However, it is limited to quantify the influence of long‐term fertilization on soil micro‐pore structure. In this study, we investigated the effect of long‐term fertilizer application on soil pore characteristics using X‐ray computed tomography. Loess soil cores were collected from four 25‐yr fertilization treatments in Guanzhong Plain, Northwest China, including no fertilization (CK), nitrogen alone (N), nitrogen + phosphorus + potassium (NPK) and organic manure + chemical fertilizer NPK (OMNPK). The results indicated that, compared with other treatments, OMNPK treatment significantly increased winter wheat (Triticum aestivum L.) yield, total porosity, soil organic carbon and total nitrogen, and decreased soil bulk density. Notably, there is greater soil pore connectivity (EuN, Euler number) and lower fractal dimension in OMNPK than other treatments. Pore size distribution showed a significant difference with different diameters in <50, 50–100, 100–1000, and >1000 μm. In contrast, pore shape distribution of soil core differed little among different treatments, while elongated shape pores were appropriately 99.5% at OMNPK with more frequency than other treatments. Co‐application of organic and inorganic fertilizers improved soil pore structure and soil physical‐chemical properties, which is beneficial for preventing soil degradation.

中文翻译：

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长期施肥对西北黄土土壤孔隙和理化特性的影响

长期施用无机和有机肥料会对土壤特性和农作物产量产生重大影响。但是，量化长期施肥对土壤微孔结构的影响是有限的。在这项研究中，我们使用X射线计算机断层摄影技术研究了长期施用肥料对土壤孔隙特征的影响。黄土土壤芯是从西北关中平原的25年施肥处理中收集的，包括不施肥（CK），仅施氮（N），氮+磷+钾（NPK）和有机肥+化肥NPK（OMNPK） 。结果表明，与其他处理相比，OMNPK处理显着增加了冬小麦（Triticum aestivum）。L.）产量，总孔隙率，土壤有机碳和总氮，以及降低的土壤容重。值得注意的是，OMNPK中的土壤孔隙连通性（EuN，欧拉数）更大，分形维数更低。孔尺寸分布在<50、50-100、100-1000和> 1000μm范围内显示出不同直径的显着差异。相比之下，在不同处理方式下，土壤核心的孔形分布差异不大，而在OMNPK上，细长形孔隙的比例适当地为99.5％，频率高于其他处理方式。有机和无机肥料的共同施用改善了土壤孔隙结构和土壤理化特性，有利于防止土壤退化。