Biochar Physical and Hydrological Characterization to Improve Soil Attributes for Plant Production

One of the most important problems in agriculture is water scarcity. Biochar, as a soil amendment, has the potential to overcome this problem by improving soil’s physicochemical and hydraulic properties. However, the study of biochar’s physical and hydraulic characteristics, its potential to improve soil physical and soil water holding capacity, and its contribution to water saving and reduction in irrigation costs is lacking. The understanding of biochar’s characteristics is so important because the effectiveness of biochar as a soil amendment is dependent on biochar properties. Our goal is to determine how biochar’s pore volume, pore size distribution, specific surface area, and water uptake by biochar interact with soil’s physical and hydraulic properties. The pore volume, pore size distribution, porous network, specific surface area, and water holding capacity (WHC) were evaluated in four biochars produced from elephant grass ( Pennisetum purpureum ), castor bean seeds, soybean seeds, and Jatropha sp. cake pyrolyzed at 380 °C. Our results demonstrated that the specific surface area and pore volume do not contribute to water uptake in hydrophobic biochars from castor bean seeds, soybean seeds, and Jatropha sp, but the results also demonstrated that these biochars have the potential to reduce soil compaction and increase soil porosity. Interestingly, the macroporosity and low hydrophobicity of the elephant grass biochar contributed to increase in its water uptake; these characteristics make this biochar promisor in increasing the soil water holding capacity and water saving and reducing the irrigation costs.