Impact of the biochar fraction sizes on the selected hydrophysical properties of silty loam soil

Abstract

Biochar is a widely known soil amendment. In the presented study, we aimed to evaluate the effect of biochar produced from Swedish willow ((Salix schwerinii x S. viminalis) x S. viminalis), ground into three different size fractions (<125µm, 125µm–2 mm and >2 mm) on selected hydrophysical properties of silty loam soils. Biochar was applied in the amount of 1.5% per weight of dry matter and the results were compared with pure silty loam soil (control). Data of biochar application impact on the selected hydrophysical properties of silty loam soil were statistically analyzed. In general, our results suggest that applied different size fractions of biochar does not have a statistically significant effect on particle density, however does have an effect on bulk density, porosity and saturated hydraulic conductivity of silty loam soil. With regard to bulk density, a statistically significant decrease (p<0.05) was observed compared to the control and it ranged from 4.18 to 8.13% from the smallest to the largest biochar fraction. The decrease of bulk density further led to a statistically significant increase (p<0.05) in porosity of all three treatments. Saturated hydraulic conductivity tended to increase as the size fraction of the biochar used was progressively reduced. This increase ranged from 63.77% (for biochar with size fraction >2 mm) to 112.42% (for biochar with size fraction <125µm) compared to pure silty loam soil (control).