The extent by which the contribution of eucalypt harvest residues (HR) to soil organic carbon (SOC) is impacted by soil disturbance during and/or after harvesting is unclear. We addressed this question by following the decomposition of HR in microplots (15-cm diameter, 15-cm height) and determining their contribution to SOC in 10 sites across southeastern Brazil. The experiment was set up according to a complete randomized block design arranged into a 3 × 2 factorial scheme including: HR removal (HR₀), only bark removal (HR − B) and HR including bark (HR + B) applied to: undisturbed soil (US) with HR left on the soil surface or disturbed soil with HR mixed into the first 5 cm of the topsoil. We had eight blocks as replicates. Following a 12-month field decomposition, soil samples were fractionated to isolate SOC within the particle-size fractions (PSF) greater and lower than 53 µm. Subsequently, we used ¹³C to quantify the effects of the treatments in C₃-derived SOC content (C₃-SOC) within each PSF. For both PSF, their C₃-SOC content increased in response to HR − B or HR + B relative to HR₀, depending on soil disturbance and HR half-life time (t_0.5). For HR − B, net increments in C₃-SOC within the PSF > 53 µm increased significantly with HR t_0.5, regardless of soil disturbance. Otherwise, the C₃-SOC content within the PSF < 53 µm increased with HR t_0.5 in response to both HR types, but only for US treatments. Overall, in regions where climate drives fast decomposition rates, on-site disturbance during and/or after harvesting should be minimized to favor the contribution of HR to SOC, particularly within the PSF < 53 µm.

桉树收获残余物（HR）对土壤有机碳（SOC）的贡献受收获期间和/或收获后土壤扰动的影响程度尚不清楚。我们通过追踪微孔（直径15厘米，高度15厘米）中HR的分解并确定其对巴西东南部10个地点的SOC的贡献来解决此问题。实验是根据完整的随机区组设计建立的，该设计分为3×2阶乘方案，包括：HR去除（HR ₀），仅将树皮去除剂（HR-B）和包括树皮的HR（HR + B）应用于：HR留在土壤表面的原状土壤（US）或HR混入表土的前5 cm的扰动土壤。我们有八个街区作为副本。经过12个月的现场分解后，将土壤样品分级，以分离出大于和小于53 µm的粒径级分（PSF）中的SOC。随后，我们使用¹³ C量化了每种PSF中C ₃衍生的SOC含量（C ₃ -SOC）的处理效果。对于两种PSF，其C ₃ -SOC含量均相对于HR ₀响应于HR-B或HR + B而增加，这取决于土壤扰动和HR半衰期（t _0.5）。对于HR-B而言，无论土壤扰动如何，当HR t _0.5时，PSF> 53 µm内C ₃ -SOC的净增量都会显着增加。否则，对两种HR类型的反应，PSF <53 µm中C ₃ -SOC的含量随HR t _0.5的增加而增加，但这仅适用于US治疗。总体而言，在气候驱动快速分解速率的区域中，应尽量减少收获期间和/或收获后的现场干扰，以利于HR对SOC的贡献，特别是在PSF <53 µm内。