Biochar Amendment Alleviates the Risk of High-Salinity Saltwater Intrusion for the Growth and Yield of Rice (Oryza sativa L.).

Introduction: Saltwater intrusion poses a serious risk to global food security. As a soil amendment, biochar mitigates the negative effects of saltwater intrusion in rice, yet the beneficial effects on agricultural productivity with different exposure times and salt concentrations have not been fully examined.

Methods: A pot experiment was conducted to investigate the effects of 30% (w/w) rice husk biochar on the growth, ion accumulation, and yield of the Phitsanulok 2 rice cultivar under salt stress due to saltwater intrusion. Rice plants were grown in saline soil amended with biochar and were salinized with 6, 8, and 10 dS/m saltwater for 1, 2, and 3 months. A treatment without biochar was taken as the control.

Results: The results showed that biochar amendment significantly increased the survival, shoot height, and tiller numbers of rice treated with the 6-10 dS/m saltwater for 1 and 2 months, as well as the treatment with 6 dS/m salt water for 3 months, in comparison with the control. The grain yield was about 40 g/pot for rice with biochar treated for 1 month with 6-10 dS/m saltwater and for the rice treated for 2 months with 6 dS/m. The results indicated that biochar application could alleviate the intrusion of high-salinity water for 1 month of salt exposure, and it could alleviate the intrusion of medium-salinity water for 2 months.

Conclusion: Therefore, a 30% (w/w) rice husk biochar amendment is a reliable strategy for mitigating the risks of saltwater intrusion for the growth and productivity of rice.