The assessment of rill irrigation and perforated pipes for Lowland paddy rice under the system of rice intensification (SRI)

Irrigated paddy rice needs new strategies and tools to improve water use efficiency and productivity by applying just enough to sustain production with huge savings on irrigation water. In this regard, an experiment was conducted in Tainan, Xuejia district where lowland paddy rice was grown under the SRI using two different irrigation methods (rill irrigation and sprinkler hose). This was conducted over a period of two years (2019 and 2020) to obtain an optimized irrigation method with high water-saving benefits and increased yields. In the first-year, rill irrigation was used with varying rill depths of 10, 20 and 25 cm (as T10, T20 and T25 treatments) under SRI, and the depth of 10 cm was found to be the most optimum, attaining a yield of 1500 kg/ha. T10 had also the highest water productivity of 0.7 kg/m3. In the second year, a sprinkler hose was used for irrigation with varying irrigation volumes of 0.3, 0.2, 0.1 m3 (as T3, T2 and T1 treatments) and the traditional SRI method as the control. All plots were irrigated at a moisture stress of 25 kPa. The 0.3 m3 treatment was effective in producing the highest yield of 950 kg/ha with a water productivity of 0.21 kg/m3. The results showed that the yield and the water productivity were 63% and 30% higher under rill irrigation, respectively, favouring the adoption of rill irrigation. Generally, lowland paddy rice performed better in the dry season for both methods applied due to high prevalence of diseases in the wet season. In conclusion, any modifications of water applied to paddy should be made during the crucial stages of grain filling to improve the fertility rate otherwise optimum yields will not be realised.