Impact of irrigation method and biochar application on growth and yield of rice

【Objective】 To study the effects of applying different amounts of biochar on the growth and yield of rice in the Jiansanjiang area under flooded irrigation and alternating wet and dry irrigation modes, and to determine the appropriate amount of biochar under different irrigation modes for rice in this area. 【Method】 The experiment was carried out as a field trial using two irrigation modes: flood irrigation (CF) and alternating wet and dry irrigation (AWD). Additionally, three biochar application rates were used: B5 (5 t/hm2), B15 (15 t/hm2), and B25 (25 t/hm2). Flooded irrigation without biochar treatment was used as the control (CK) to study the effects of different biochar application rates on rice growth and yield under two irrigation modes. 【Result】 The application of biochar promoted plant tillering and plant height growth under both irrigation models, but the difference with CK was not significant. Biochar application favored rice LAI, dry matter and yield formation in the Jiansanjiang area, with the most pronounced effect in the B15 treatment. The LAI, dry matter mass and yield of rice in B15 treatment under CF irrigation mode were significantly increased by 39.8%, 17.0% and 10.0%, respectively, compared with those in CK. The LAI, dry matter mass, and yield of rice in B15 treatment under AWD irrigation model were significantly increased by 36.9%, 18.3%, and 11.3%, respectively, compared with those in CK. Irrigation modes had less effect on tillering and plant height of rice under the same biochar application rate, but AWD irrigation model was more favorable for dry matter mass and yield. Mean rice dry matter mass and yield increased by 1.0% and 0.8%, respectively, under the AWD irrigation mode compared to the CF irrigation mode. Water consumption of rice under CF irrigation mode was similar to that of CK, whereas water consumption of rice under AWD irrigation mode was 11.0% less than that of CK. Water use efficiency in AWD irrigation mode increased by 13.3% than that of CF mode. Under the same irrigation mode, rice water use efficiency was significantly higher in the B15 treatment than in the other treatments. Water use efficiency of B15 treatment was 9.7% and 25.5% higher than that of CK under CF and AWD irrigation mode, respectively. 【Conclusion】 The application of biochar in the Jiansanjiang area can promote the growth and yield formation of rice, and the increase in yield firstly increases with the increase of biochar application rate and then decreases, taking into account the increase in yield, water saving and other factors, the 15 t/hm2 biochar application rate in the AWD mode is the best water-charcoal coupling mode.