The objective of this study was to synthesize, characterize, and modify rice and wheat straw biochar for various parameters (pH, EC, organic carbon and organic matter, N, P, and K). In this experiment, rice straw biochar (RSB) and wheat straw biochar (WSB) production applied temperature at 300 °C. These biochars’ chemical modification with hydrochloric acid (HCl) and sulfuric acid (H₂SO₄) resulted in four variants: HCl-modified rice straw biochar (MRSB-1); H₂SO₄-modified rice straw biochar (MRSB-2); HCl-modified wheat straw biochar (MWSB-1); and H₂SO₄-modified wheat straw biochar (MWSB-2). Comprehensive characterization revealed that rice and wheat straw biochar, when modified with HCl and H₂SO₄ changed the values of pH (7.6 to 5.4), EC (1.51 to 0.28), organic carbon (53.65 to 48.25), organic matter (92.28 to 82.99), N (1.68 to 0.84), P (2.66 to 1.54), and K (3.85 to 1.98). However, the impact of H₂SO₄-modified biochars remained more prominent than the others.

Keywords: Biochar, rice straw, wheat straw, modified, H₂SO₄, HCl

Key findings: Modifications of biochars with acids proved fruitful in all characteristics, but the use of H₂SO₄, when assessed, emerged superior to HCl.