Limited information is available related to soil organic carbon (SOC), nitrogen (N), and their associated fractions, especially in diversified cropping sequences with a combination of tillage systems. Therefore, a field study was conducted to evaluate the effects of cropping sequences and tillage systems on SOC and N and associated fractions. The experiment was comprised of two factors, i.e., (i) tillage systems: no tillage (NT) and rotary tillage (RT), and (ii) cropping sequences: wheat-soybean-wheat-maize (WSWM); wheat-maize-wheat-soybean (WMWS); wheat-soybean-wheat-soybean (WS); and wheat-maize-wheat-maize (WM). Tillage systems influenced the distribution of SOC and N and their associated fractions mainly at topsoil depth rather than deep soil, while cropping sequences affected SOC and N and their associated fractions differently in the whole soil sampling depth (0–50 cm). The results showed that NT had significantly higher SOC concentrations than RT at the 0–10- (17% higher) and 20–30-cm (19% higher) soil layers. Similarly, NT had 17% significantly higher N contents than RT at the 0–10-cm soil layer, but RT had 21% significantly higher N accumulation at the 10–20-cm soil layer. The particulate organic carbon (POC) was highest in WM and lowest in WS cropping sequence at 0–10-cm soil depth, while tillage did not affect POC distribution at 0–30-cm soil depth. Similarly, particulate organic nitrogen (PON) was significantly higher in soybean-included cropping sequences only at 0–10-cm soil depth. Some other fractions, such as dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), were higher in soybean-included cropping sequences at 0–30- and 0–20-cm soil depths respectively. Mineral-associated organic carbon (MAOC) also increased by 28% and 34% (p < 0.05) under NT compared to RT at the 0–10- and 10–20-cm soil layers, respectively. In the case of cropping sequence comparison, WSWM had 30% higher SOC at the 10–20-cm soil layer than the other three cropping sequences. Notably, legume-included cropping sequences (WSWM, WMWS, WS) significantly increased N contents by 9%, 15%, and 22% and mineral-associated organic nitrogen (MAON) by 12%, 15%, and 17.5%, respectively, compared to the WM cropping sequence at the 0–10-cm soil layer. SOC and TN and their fractions were redistributed by tillage and cropping sequences at 20–50-cm soil layers. However, SOC stock was only affected by tillage systems (NT had 10% higher than RT) rather than cropping sequences. But WMWS and WS cropping sequences had 11% and 10% significantly higher N stock than WSWM and WM sequences, respectively. Overall, our findings suggested that NT especially with soybean could be a suitable practice to sequester SOC and N in the North China Plain.

关于土壤有机碳（SOC），氮（N）及其相关组分的信息有限，尤其是在结合耕作系统的多样化种植序列中。因此，进行了田间研究，以评估种植顺序和耕作制度对SOC，N及相关组分的影响。该实验由两个因素组成，即（i）耕作制度：免耕（NT）和旋耕（RT），以及（ii）种植顺序：小麦-大豆-小麦-玉米（WSWM）；小麦-玉米-小麦-大豆（WMWS）；小麦-大豆-小麦-大豆（WS）；和小麦-玉米-小麦-玉米（WM）。耕作制度主要在表土深度而非深层土壤中影响SOC和N及其相关组分的分布，在整个土壤采样深度（0–50 cm）中，种植顺序对土壤有机碳和氮及其相关组分的影响不同。结果表明，在0–10-（高17％）和20–30-cm（高19％）土壤层，NT的SOC浓度明显高于RT。同样，在0–10 cm土层，NT的氮含量比RT高17％，但是在10–20 cm土层，RT的氮积累高21％。在土壤深度为0–10 cm时，颗粒有机碳（POC）在WM中最高，而在WS种植顺序中最低，而耕作对土壤深度为0–30 cm时的POC分布没有影响。同样，仅在土壤深度为0-10 cm的情况下，包括大豆在内的种植顺序中的颗粒有机氮（PON）明显更高。其他一些分数，包括大豆在内的作物种植顺序在土壤深度为0–30-cm和0–20-cm时分别较高，例如溶解有机碳（DOC）和溶解有机氮（DON）。矿物相关有机碳（MAOC）也分别增长了28％和34％（p 分别在0–10-cm和10–20-cm的土壤层上，与RT相比，在NT下<0.05。在比较种植顺序时，WSWM在10–20 cm土层的SOC比其他三个种植顺序高30％。值得注意的是，含豆类作物的种植顺序（WSWM，WMWS，WS）分别使氮含量分别提高了9％，15％和22％，而与矿物质相关的有机氮（MAON）分别提高了12％，15％和17.5％。与0-10厘米土壤层的WM种植顺序相比。SOC和TN及其分数通过耕作和耕作顺序在20–50 cm土层上重新分布。但是，SOC储量仅受耕作系统的影响（NT比RT高10％），而不是种植顺序。但是WMWS和WS的种植顺序分别比WSWM和WM的顺序高出11％和10％。总体，