The particle size (PS) and application rate (RA) of biochar influence soil–biochar interaction with concomitant effects on soil chemical and physical properties. However, limited studies exist that quantify how biochar PS and RA, acting solely or together affect soil structure characteristics and functional properties. This study investigated the effect of PS and RA of corn cob biochar on soil water retention (SWR) and aeration indicators such as relative gas diffusivity, structural characteristics such as pore size distribution and pore organisation, and consistency limits of a tropical sandy clay loam soil. A pot experiment was conducted using two biochar PSs (<2 and 2–4 mm) and four biochar RAs of 0, 20, 40 and 80 Mg ha−1. Both intact soil cores (100 cm3) and disturbed bulk soil samples were collected after 36 months of amendment for measurements of soil chemical and hydraulic properties, and consistency limits. Biochar application of 80 Mg ha−1 significantly (P < 0.05) increased soil organic carbon and SWR. However, plant available water was neither affected by biochar PS nor RA. Further, biochar PS and RA acting solely or together did not significantly modify air permeability, consistency limits and estimated soil pore continuity, organisation and tortuosity. Further studies are needed to confirm whether the overall lack of significant changes in these soil properties after 36 months of amending with corn cob biochar also pertains to other biochar feedstock and soil types. Such information is useful in selecting suitable biochar amendments that improve soil conditions for crop growth.

中文翻译：

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在为期 36 个月的盆栽试验中，土壤结构特征、功能特性和一致性限制了对玉米芯生物炭粒径和施用率的响应

生物炭的粒径 (PS) 和施用率 (RA) 会影响土壤与生物炭的相互作用，并同时影响土壤的化学和物理特性。然而，量化 biochar PS 和 RA 单独或共同作用如何影响土壤结构特征和功能特性的研究有限。本研究调查了玉米芯生物炭的 PS 和 RA 对土壤保水率 (SWR) 和通气指标（例如相对气体扩散率、孔径分布和孔隙组织等结构特征以及热带砂质粘壤土的稠度限制）的影响. 使用两种生物炭 PS（<2 和 2-4 毫米）和 0、20、40 和 80 Mg ha-1 的四种生物炭 RA 进行盆栽实验。经过 36 个月的修正后，收集了完整的土壤核心 (100 cm3) 和扰动的大块土壤样品，用于测量土壤化学和水力特性以及一致性限制。施用 80 Mg ha-1 的生物炭显着 (P < 0.05) 增加了土壤有机碳和 SWR。然而，植物可用水不受 biochar PS 和 RA 的影响。此外，生物炭 PS 和 RA 单独或共同作用不会显着改变透气性、稠度限制和估计的土壤孔隙连续性、组织和弯曲度。需要进一步的研究来确认在使用玉米芯生物炭改良 36 个月后这些土壤特性总体上没有显着变化是否也与其他生物炭原料和土壤类型有关。