The role of biochar particle size and hydrophobicity in improving soil hydraulic properties

作者：Ifeoma Gloria Edeh, Ondřej Mašek · 发表于：European Journal of Soil Science · 年份：2021 · DOI：10.1111/ejss.13138 · 被引用次数：121 · 研究领域：Soil and Unsaturated Flow、Landfill Environmental Impact Studies、Soil Carbon and Nitrogen Dynamics

Abstract The physical properties of biochar have been shown to dramatically influence its performance as a soil amendment. This study assessed the role of biochar particle size and hydrophobicity in controlling soil water movement and retention. Softwood pellet biochar in five particle size ranges (>2 mm, 2–0.5 mm, 0.5–0.25 mm, 0.25–0.063 mm and <0.063 mm) was used for the experiment. These particle sizes were tested on two soil types (sandy loam and loamy sand) at four different application rates (1, 2, 4 and 8%) in the laboratory. Soil water suction at wet range and dry range were measured using the Hyprop and WP4‐T, respectively. From this, the moisture content at field capacity ( fc ), permanent wilting point ( pwp ) and plant available water ( awc ), were determined. Saturated hydraulic conductivity (K sat ) was measured using the KSAT device and biochar hydrophobicity was determined using the ethanol drop test method. Our results showed that biochar hydrophobicity increased with decreasing biochar particle size, leading to a reduction in its water retention capacity. The highest fc (0.087 cm −3 cm −3 ) and awc (0.064 cm −3 cm −3 ) were observed for soils amended with >2 mm biochar. The soil hydraulic conductivity increased with decreasing biochar particle sizes, with the exception of <0.063 mm biochar, which showed a significant ( p ≤ 0.05) decrease in soil hydraulic conductivity compared to the larger particle sizes. The results clearly showed that both biochar intrapo...