Impact of Organic Amendment with Alternate Wetting and Drying Irrigation on Rice Yield, Water Use Efficiency and Physicochemical Properties of Soil

A pot experiment was executed to investigate the impact of biochar and compost with water-saving irrigation on the rice yield, water use efficiency, and physicochemical properties of soil. Two irrigation regimes—namely alternate wetting and drying (AWD) and continuous flooding (CF)—and four types of organic amendments (OA)—namely rice husk biochar (RHB), oil palm empty fruit bunch biochar (EFBB), compost and a control—were applied to evaluate their effects. Under the AWD irrigation regime, the maximum grain was produced by RHB (241.12 g), whereas under the same organic amendments, both AWD and CF produced a similar grain yield. Under the same organic amendment, a significantly higher water use efficiency (WUE) was observed from the AWD irrigation with RHB (6.30 g L−1) and EFBB (5.80 g L−1). Within the same irrigation regime, soil pH, cation exchange capacity, total carbon, total nitrogen and available phosphorus were enhanced due to the incorporation of biochar and compost, while higher soil exchangeable potassium was observed under CF irrigation for all treatments. RHB and EFBB significantly reduced the soil bulk density (up to 20.70%) and increased porosity (up to 16.70%) under both irrigation regimes. The results imply that the use of biochar with AWD irrigation could enhance the nutrient uptake and physicochemical properties of soil and allow rice to produce a greater yield with less water consumption.