Long-Term Effects of Palm Leaf Biochar on the Porosity and Structure Stability of a Sandy Clay Loam Soil

Biochar in soil is an alternative way to increase soil carbon in the long term and improves soil physical properties. The aim of this study was to investigate the long-term effect of palm leaf biochar on different types of soil porosity (air filled, capillary, and total) and structure stability of a sandy clay loam soil. A factorial experiment was performed in pots using a completely randomized design with two factors including the amount of biochar of date leaves at four levels (control=B0, B0.5=0.5%, B1=1%, and B2=2% by weight) and the time after application of biochar at four levels (T1 =one, T3 =3, T6 =6, and T9 =9 months ), with three replications.The results showed that the effect of palm leaf biocharon air-filled and capillary porosity was significant. Also, the effect of time after biochar application on bulk density and porosity was significant.The effect of biochar amount, time after biochar application, and their interaction effects on mean weight diameter (MWD) of aggregates were significant. The highest percentage of increases in treatments compared to the control (B0T1) belonged to B2T6 in bulk density (14.7%), total porosity in B2T1 (5.4%), capillary porosity in B2 (64.3%), MWD of aggregates by dry sieve method in B1T9 (28%), and MWD of aggregates by wet sieve method in B2T1 (63.2%). The results showed that the highest effect of biochar on bulk density, total porosity, capillary porosity, and MWD of aggregates by wet sieve method was in the first month, and on MWD of aggregates by dry sieve method was in the ninth month, while the effect of time on changes in air filled porosity was not significant.Overall, biochar with significant porosity and carbon content improved the porosity and soil structure stability in this study. Therefore, biochar can be used to improve structure of degraded and weak soils.