Utilizing rainfall and alternate wetting and drying irrigation for high water productivity in irrigated lowland paddy rice in southern Taiwan

AbstractTaiwan’s average annual rainfall is high compared to other countries around the world; however, it is considered a country with great demand for water resources. Rainfall along with alternate wetting and drying irrigation is proposed to minimize water demand and maximize water productivity for lowland paddy rice cultivation in southern Taiwan. A field experiment was conducted to determine the most suitable ponded water depth for enhancing water saving in paddy rice irrigation. Different ponded water depths treatments (T2 cm, T3 cm, T4 cm and T5 cm) were applied weekly from transplanting to early heading using a complete randomized block design with four replications. The highest rainwater productivity (2.07 kg/m3) was achieved in T5 cm and the lowest in T2 cm (1.62 kg/m3). The highest total water productivity, (0.75 kg/m3) and irrigation water productivity (1.40 kg/m3) was achieved in T2 cm. The total amount of water saved in T4 cm, T3 cm and T2 cm was 20, 40, and 60%, respectively. Weekly applica...