Careful nutrient management to increase soil organic carbon (SOC) content is important in increasing agricultural productivity and maintaining ecosystem health. A field experiment was conducted for nine years to investigate the effects of manure (M) and inorganic fertilizer (NPK) on SOC and its labile fractions within the bulk soil and in soil aggregates in a wheat-maize rotation on the North China Plain. Nine treatments were included: control (CK) with no fertilization, cattle manure (M, applied at rates of 3000, 6000, 9000, and 12,000 kg ha⁻¹ crop⁻¹), and inorganic NPK fertilizer applied to give equivalent rates of N, P and K. Straw was returned to all plots. Results showed that fertilization significantly increased SOC sequestration and the concentrations of SOC and labile SOC fractions (cold water - extractable SOC, hot water-extractable SOC, microbial biomass C, and dissolved organic C within the bulk soil and soil aggregates). The values increased with increasing application rate of manure but not with increasing NPK fertilizer rate. The differences between manure and NPK fertilizer were apparent at rates equivalent to 9000 and 12,000 kg manure ha⁻¹. Labile SOC fractions were linearly correlated with SOC within the bulk soil and aggregates and hot water-extractable C was the labile C fraction most sensitive to changes in SOC content. Aggregate stability was significantly positively correlated with SOC content and its labile fractions in both bulk soil and aggregates. The results indicate that straw return and/or combined application of fertilizers and manures may be feasible in achieving the ‘4 per 1000’ initiative, with manure application particularly effective. Manure application at a rate of 9000 kg ha⁻¹ crop⁻¹ may be the optimum strategy to sequester C and maintain high crop productivity. Periodic high application rates of manures should be integrated with appropriate inorganic fertilizer application rates to optimize nutrient management strategies on calcareous soils.

认真进行养分管理以增加土壤有机碳（SOC）含量对于提高农业生产力和维持生态系统健康至关重要。进行了九年的田间试验，研究了华北平原小麦-玉米轮作中粪肥（M）和无机肥料（NPK）对土壤和土壤团聚体中SOC及其不稳定组分的影响。包括九种处理：不施肥的对照（CK），牛粪（M，以3000、6000、9000和12,000 kg ha ^-1作物^-1的施用量），然后施用无机NPK肥料以产生等量的N，P和K。将秸秆还给所有地块。结果表明，施肥显着增加了SOC的固含量以及SOC浓度和不稳定的SOC组分（冷水-可萃取SOC，热水可萃取SOC，微生物量C和微生物在土壤和土壤团聚体中的有机碳含量）的浓度。该值随肥料施用量增加而增加，但不随NPK施肥量增加而增加。粪肥和氮磷钾肥料之间的差异很明显，分别相当于9000和12,000公斤粪便ha ^-1。不稳定的SOC分数与散装土壤和团聚体中的SOC呈线性相关，而热水可萃取的C是对SOC含量变化最敏感的不稳定的C分数。散装土壤和骨料中骨料的稳定性与SOC含量及其不稳定部分呈显着正相关。结果表明，秸秆还田和/或肥料和肥料的联合施用在实现“千分之四”计划方面可能是可行的，其中粪便施用特别有效。施用量为9000 kg公顷^-1作物^-1可能是隔离C和维持高作物产量的最佳策略。定期将高肥料施用量与适当的无机肥料施用量结合起来，以优化石灰性土壤的养分管理策略。