Biochar enhances soil hydrological function by improving the pore structure of saline soil

The poor soil structure caused by salinization is a major factor affecting crop growth and soil structure will further affect hydrological function. Biochar is widely used to improve soil physical structure because of its special porous material. However, the mechanism of soil pore structure on hydrological function (e.g., soil saturated hydraulic conductivity, plant available water, least limiting water range) after biochar incorporation in saline soil remains unclear. Therefore, the present study examined the response of soil structural properties of different biochar addition in saline clay loam, and subsequently assessed how the pore structure influence soil hydrological function. The study involved four treatments: CK (Control)、C 1 (7.5 t ha −1 biochar)、C 2 (15 t ha −1 biochar)、C 3 (30 t ha −1 biochar). Soil aggregate stability increased from 15 % to 30 % when the amount of biochar addition increased from 7.5 t ha −1 to 30 t ha −1 . The highest connectivity index (2.36) and the highest fractal dimension (2.56) were found at the biochar addition of 30 t ha −1 . Biochar addition reduced the proportion of small pores (300 µm pore size). Biochar amendment reduced the soil penetration resistance, with the soil saturated hydraulic conductivity, plant available water and the least limiting water range were measured 46 %, 27 % and 40 % greater in rate of 30 t ha −1 biochar addition as compared with those of the CK, respectively. Pearson’s correlation analysis and redundancy analysis revealed that the soil saturated hydraulic conductivity was positively correlated with large pores (diameter >300 μm) and pore connectivity ( p 300 µm pore size). • The least limiting water range at 30 t ha −1 biochar addition were greater compared with the control. • The pore connectivity and elongated pore were the dominant drivers of least limiting water range increase. • Biochar-amended saline soil pore structure has the positive effect on hydrological function.