In environments where continuous agriculture leads to soil organic carbon (SOC) depletion, intensification practices (i.e. polyculture, cover crops (CC), and crop fertilization) have been suggested as strategies to improve crop residue inputs which, in turn, can increase SOC storage. However, SOC dynamics are regulated by a complex interplay of climatic and soil conditions. The objective of our study was to assess how intensification practices affect SOC, particulate organic carbon (POC) and SOC stratification ratio (SR_SOC) as compared to soybean [Glycine max (L.) Merr.] monoculture, in soils with contrasting soil properties and climate. The experiment was carried out in four long term experiments (>10 yr) located in areas with contrasting environments. The surface soil textures ranged from sandy-loam to silty-clay and clay-loam, initial SOC (0–20 cm) from 34.5 to 67.8 Mg ha⁻¹, mean air temperature: 14.0–18.9 °C, annual precipitation: 719.8–886.1 mm. Five treatments were evaluated: soybean monoculture (SB), soybean monoculture fertilized with phosphorus (P) and sulfur (S) (SB_PS), CC/PS-fertilized soybean (SB_PS/CC), nitrogen (N)-fertilized CC/PS-fertilized soybean (SB_PS/CC_N) and NPS-fertilized crop rotation (ROT_NPS). Intensification of crop sequences (SB_PS/CC, SB_PS/CCN and/or ROT_NPS) increased SOC and POC at 0–5 cm and in SR_SOC in most sites as compared to SB. All treatments showed SOC depletion as compared to the beginning of the experiment. However, the magnitude of SOC lost during 10 years was 26–65% lower when intensified crop sequences were applied as compared with SB. Carbon input and environment characteristics influenced the impact of intensification practices on the analyzed variables. However, this effect was mostly associated with the ratio between SOC at the beginning of the experiment and the SOC of pristine soil (degradation status). The intensification practices evaluated were not sufficient to reverse the tendency of agricultural soils to lose SOC, but they slowed the rate of this degradation process.

在连续农业导致土壤有机碳（SOC）耗竭的环境中，有人建议采用集约化做法（即混养，覆盖作物（CC）和作物施肥）作为改善作物残渣输入量的策略，从而增加SOC的存储量。但是，SOC动态受气候和土壤条件复杂相互作用的影响。我们研究的目的是评估集约化做法如何影响SOC，颗粒有机碳（POC）和SOC分层比率（SR _SOC）相比，大豆[甘氨酸max（L.）Merr。]单作，在土壤特性和气候形成鲜明对比的土壤中。该实验是在环境相反的地区进行的四个长期实验（> 10年）进行的。表层土壤的质地范围从沙质壤土到粉质粘土和黏土壤土，初始SOC（0-20 cm）从34.5至67.8 Mg ha ^-1，平均气温：14.0-18.9°C，年降水量：719.8– 886.1毫米 评价了五种处理方式：大豆单培养（SB），施以磷（P）和硫（S）的大豆单培养（SB _PS），经CC / PS施肥的大豆（SB _PS / CC），经氮（N）施肥的CC / PS施肥的大豆（SB _PS / CC _N）和NPS施肥的作物轮作（ROT _NPS）。作物序列（SB _PS / CC，SB _PS / CCN和/或ROT _NPS）的集约化增加了0-5 cm和SR _SOC的SOC和POC与SB相比，在大多数网站上 与实验开始相比，所有处理均显示SOC耗尽。但是，与SB相比，强化施肥顺序可降低10年间SOC损失的幅度达26-65％。碳输入和环境特征影响了强化实践对所分析变量的影响。但是，这种影响主要与实验开始时的SOC与原始土壤的SOC之比（降解状态）有关。评估的强化措施不足以扭转农业土壤失去SOC的趋势，但它们减慢了降解过程的速度。