Fertilization is the most common way to supply nutrients to the soil and to maintain crop productivity in agricultural ecosystems, which may also influence soil organic carbon (SOC) accumulation rates. In 1996, we set up a long‐term field experiment to explore the effect of fertilization on soil properties in a winter wheat–summer maize cropping system in the North China Plain. Eight treatments included: no fertilization (Ct), nitrogen (N), phosphorus (P) and N combined with P (NP) fertilizer application with or without potassium (K). After 21 years of fertilization, N application did not increase soil total N content, but P application significantly increased soil total P contents by 33.9%. The single application of N or P did not significantly affect SOC content, whereas the NP combination significantly increased SOC contents by 22.1 and 29.6% compared to Ct in the no K and K treatments, respectively. The natural ¹³C abundance approach and the SOC contents suggested that the NP combination increased C3 wheat‐derived SOC by 37.5 and 49.8% in the no K and K treatments, respectively. However, fertilization had no impact on C4 maize‐derived SOC content. Wheat‐derived SOC was positively correlated with the wheat yield, whereas maize‐derived SOC was not correlated with the maize yield, which indicated that wheat‐derived SOC accumulated more than maize‐derived SOC in the wheat–maize cropping system. In addition, soil inorganic carbon (SIC) and its compositions were not affected by the long‐term fertilization. Our results indicate that N combined with P application is more beneficial than N or P alone to enlarge SOC sequestration in the North China Plain, especially for wheat‐derived SOC. Thus, in soil with nutrient limitations, nutrient resources should be supplied with priority to the wheat growing season in wheat–maize cropping systems, to maintain or enlarge SOC storage.

中文翻译：

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21年后，在小麦-玉米种植系统中，源自小麦的土壤有机碳的累积量高于玉米的累积量

施肥是向土壤供应养分并维持农业生态系统中作物生产力的最常见方法，这也可能影响土壤有机碳（SOC）的积累速率。1996年，我们建立了一个长期的田间试验，以探讨施肥对华北平原冬小麦—夏季玉米种植系统中土壤特性的影响。八种处理方式包括：不施肥（Ct），不施氮（N），不施磷（P）和施氮（P）（NP）结合施有或不施钾（K）。施肥21年后，施氮并没有增加土壤总氮含量，但施磷显着增加了土壤总磷含量33.9％。单独施用N或P不会显着影响SOC含量，而NP组合显着增加SOC含量22.1和29。在无钾和无钾处理中，Ct分别为6％。自然¹³C丰度法和SOC含量表明，NP组合在无K和K处理下分别使C3小麦来源的SOC增加37.5和49.8％。但是，施肥对C4玉米衍生的SOC含量没有影响。小麦来源的SOC与小麦产量成正相关，而玉米来源的SOC与玉米产量不相关，这表明在小麦-玉米种植系统中，小麦来源的SOC比玉米来源的SOC积累更多。此外，土壤无机碳（SIC）及其组成不受长期施肥的影响。我们的结果表明，氮肥与磷肥配施比单独施用氮肥或磷肥更有利于扩大华北平原的SOC隔离，特别是对于小麦衍生的SOC。因此，在营养有限的土壤中，