Effect of biochar and quicklime on growth of wheat and physicochemical properties of Ultisols

Acidity of soils poses numerous drastic impacts on physical and chemical properties of soils along with diminishing the soil nutrient status. A pot experiment was conducted to improve the soil physicochemical properties and wheat production in strongly acidic soils (Ultisols) of tropical and subtropical regions of China. Sludge biochar (C1), straw biochar (C2), and quicklime (CaO) were applied in different combinations in the soil, and wheat was grown till maturity. The results revealed that at 4% C1 + 100% CaO, soil pH was amplified by 64%, while exchangeable H+ and Al3+ contents reduced significantly at C1 treatment with and without lime application (p˂0. 05). A significant reduction of 18 and 17% in soil bulk density was observed at 4% C2 and 4% C2 + 50% CaO, respectively. Soil surface cracks in terms of crack area and crack length at 2% C1 + 50% CaO were reduced by 33 and 29%, respectively. Tensile strength of red soil decreased with the addition of amendments and the highest decrease (31%) in tensile strength was observed at 4% C1 + 50% CaO. Shear strength tests exposed that biochar and lime treatments showed slight enhancement (15%) in the internal friction angle (φ) at 2% C1 + 100% CaO and decreased (83.31 and 84.22%) the cohesion (c) value at 2 and 4% C1 in combination with a 50% CaO. The amendments in combination significantly increased the wheat biomass and wheat grain yield (103 and 131%), respectively, at 4% C2 + 100% CaO as compared to the control. The recent study suggests that biochar as well as lime can be effective to improve the physicochemical properties of red soils and wheat yield.