Irrigation Interval for Paddy Grown in Red Yellow Podsolic Soils in Low Country Intermediate Zone

Abstract

Water wastage is very high under irrigated rice culture since standing water or flooded condition is practiced. Therefore, as an alternative to continuous flooding, alternate wetting and drying techniques can be introduced to use water more effectively. Since interval between wetting and drying varies mainly with the soil type, this study was conducted to determine the suitable irrigation interval for paddy grown in poorly drained red yellow podsolic soil (RYP) belong to Kurunegala soils series in low country intermediate zone. Field trials werg established at the Rice Research and Development Institute, Bathalagoda during 2011 yala season. Rice variety used was Bg359. Six irrigation intervals T, (irrigation up to 5 cm above ground level at saturate condition) T2 (irrigation up to 5cm above ground level at 3 days interval), T3 (irrigation up to 5cm above ground level at 7 days interval) and T4 (irrigation up to 5cm above ground level at 10 days interval) T5 (irrigation up to 5cm above ground level at 14 days interval) T6 (irrigation up to 5cm above ground level at mid day wilting) were used as treatments. Number of days to 50% and 100% flowering, dry weight of stem, root and panicle at panicle initiate stage, 50 % flowering and 85% maturity were recorded. The lowestyield showed in T6 (3.2t/ha). Yields of Tl, T2, T3, and T4 were 5.0t/ha, 5.1t/ha, 4.9t/ha, 4.8t/ha, respectively and yields differences among the above four treatments were statistically not.significant (P>0.05). Results showed that standing water is necessary only at the critical stage (one week before and one week after maximum flowering) to avoid moisture stress and yield reduction. According to above results, irrigation interval could be extended up to 10 days in poor drained RYP in the Low Country Intermediate Zone (LCIZ) without significant growth and yield losses of the variety Bg359.