Acid Modification and Characterization of Rice Straw Biochar and its Potential as Ameliorant for Saline-Sodic Lowland Soil

Abstract

The study aimed to characterize the physicochemical properties of acidified biochar derived from rice straw. The characterization provides useful information on the potential use of rice straw biochar to attain optimal outcomes for environmental or agricultural applications. In this study, rice straw biochar was acidified using 0.1 N HCl three times, followed by washing with deionized water twice, air-dried for seven days, and oven-dried at 80 °C for 8 hours. The characterization showed that the physicochemical properties generally reduced after acid modification. The FESEM-EDS revealed no apparent changes in surface morphology, while elements C, Si, O, N, P, K, Mg, S, Na, Cl, and Al were all determined in acidified biochar. The BET showed that acid modification and pulverization caused a decrease in surface area, pore volume, and pore radius. In ATR-FTIR, additional peaks of carbonyl (C=O Stretch) and alkane (C-H Bend) were identified. Furthermore, XRD showed that acidified biochar confirmed the amorphous structure of the material. In the initial assessment, the addition improved the physicochemical properties of saline-sodic soil by decreasing the pH, ESP, and SAR while increasing WSA, CEC and Mg. Given the results, the reduction and improvement in the properties of acidified biochar demonstrate its potential as soil ameliorant for saline-sodic soil.

Keywords

• biochar
• rice straw
• saline-sodic soils
• amelioration
• acid modification