Effects of Date Palm Biochar on Hydraulic Properties of Calcareous Sandy Soil: Influence of Temperature, Particle Size and Application Depth.

Effects of date palm biochar on hydraulic properties of calcareous sandy soil: Influence of temperature, particle size and application depth Abdulrasoul Al-Omran, Mohammad I. Al-Wabel, Alaa Ibrahim and Adel R.A. Usman Department of Soil Science, Saudi Biochar Research Group, King Saud University, P.O. Box 2460, Riyadh, 11451,4 Saudi Arabia. Corresponding author. Tel.: +966 1 467 8444; fax: +966 1 467 8440. E-mail: rasoul@ksu.edu.sa. ABSTRACT A laboratory column experiments were conducted to investigate the effects of date palm waste (biochar) pyrolyzed at different temperatures (300, 500 and 700°C) with different particle sizes and application depths on hydro-physical properties of sandy loam soil including: soil water penetrability, infiltration rate, intermittent evaporation, water retention and saturated hydraulic conductivity. Biochar produced from date palm wastes was applied at 15 g kg-1 (21.9 t ha-1) in different sizes ((< 0.5 mm (S1), 0.5-1mm (S2) and 1-2 mm (S3)) as biochar-soil mixture layer 2-cm thick at 0 cm depth (D0), and 5 cm depth (D5) . The results indicated that applying date palm biochar decreased the waterfront and saturated hydraulic conductivity of sandy loam soil. The cumulative evaporation was the highest and amounted to 44.00 mm in the non-treated soil, but it recorded the lowest amount of 32.25-35.46 mm in the date palm biochar-treated soil with < 0.5 mm in size. The biochar addition caused significant (P<0.05) increases in the amount of conserved and retained water compared to control soil. The highest amount of water conserved in soil was found for S1 biochar at D5. In addition, the cumulative water infiltration through the soil was significantly reduced by S1 and S2 biochars at D0. The values of saturated hydraulic conductivity for the biochar treatments were significantly (P<0.05) lower than those for the control, with the lowest values for S1 at D0 and D5. These results strongly suggest positive improvement for some hydro-properties of coarse-textured soils following date palm biochar addition, especially finer particles (? 1 mm) of biochar. Key Words: Date palm biochar, Hydro-physical properties, Intermittent evaporation, Water retention, Hydraulic conductivity, Cumulative infiltration.