Rice Husk Biochar and Alternate Wetting and Drying Irrigation Influence the Grain Yield and Water Productivity of Wet Direct‐Seeded Rice

ABSTRACT Biochar application and alternate wetting and drying (AWD) irrigation are promising practices for achieving cleaner rice production. This study evaluated the combined effects of biochar and AWD irrigation on the grain yield and water productivity (WP) of wet direct‐seeded rice (WDSR). A pot experiment combining five biochar doses (0, 5, 10, 15 and 20 t ha −1 ) with three soil water potential levels (0, −15 and −30 kPa) via AWD irrigation was conducted. Biochar at 20 t ha −1 significantly increased panicle number plant −1 (18%) and SPAD value (5%) compared with 0 t ha −1 biochar. The performance of the plants was similar between 0 and −15 kPa, whereas −30 kPa was stressful. Despite the reduced water input, −30 kPa resulted in 27% lower grain yield compared with 0 kPa at 0 t ha −1 . In contrast, −15 kPa did not cause notable growth or yield abnormalities. Moreover, 20 t ha −1 in combination with −15 kPa resulted in better crop performance, resulting in 86% greater root dry matter, 24% greater grain yield and 85% greater WP than those of the control. The results highlight the potential of the integrated application of biochar and AWD irrigation for enhancing the grain yield and WP of WDSR.