عنوان مقاله [English]
Lack of organic matter in numerous soils in Iran caused unstable soil structure, compaction and land degradation. One of the methods for improving soil quality is the application of cheap organic conditioner such as biochar and compost. Biochar is the carbon-rich product obtained by heating biomass in a closed system under limited supply of oxygen. Biochar represents a soil conditioner that can change soil physical and chemical properties, but little information is available about the biochar-induced changes on physical properties of fine textured soils. This research was conducted to study the effects of biochar and compost sugarcane bagasse on some soil dynamic properties (shear strength, coefficient of linear extensibility (COLE), liquid limit (LL), plastic limit (PL) moistures and plasticity index). The experiment was conducted with randomized completely design with three replicates. The treatments were including biochar at 4 rates (0, 2%, 4% and 6%) and compost at 3 rates (0, 10, 20 and 30 tons/ha) were added into columns of PVC with diameter of 10 cm and length of 45 cm after 6 month in a soil. A lab-scale slow pyrolyzer was used for biochar production under oxygen-limiting conditions at 550 C. The produced biochars were sealed in an airtight container at 550 C and stored at room temperature until use. After preparation the soil columns treatments were incubated for 6 in a greenhouse with field capacity moisture content of 70%. The results showed that biochar and compost values significantly decreased shear strength and COLE in comparison with the control (P < 0.01). The results showed significant negative correlation between OC and shear strength in biochar (r = - 0.89) and compost (r = - 0.79) (P< 0.01). Moistures of LL and PL significantly increased for biochar treatments (P < 0.01) and compost treatments (P < 0.05). Significant and positive correlation was found between OC with LL for biochar (r = 0.8, P < 0.01) and compost treatments (r = 0.6, P < 0.05), also there was positive correlation between PL and OC in biochar treatments (r = 0.79, P < 0.01) and compost treatments (r = 0.8, P < 0.01). The effect of compost on PI was not significant. Significant and positive correlation was found between OC and PI in biochar treatment in level of 6% (r = 0.71, P < 0.01). This research indicated that biochar and compost sugarcane bagasse as an organic conditioner improved mechanical quality of the soil. The result from this short-term localized study will need to be supported by additional long-term studies or in field condition to determine the long term effect of biochar amendment on soil. Therefore, additional field studies using biochar as a soil amendment over a longer period of time is recommended.