1. Water management Soil and Nutrients Pests and diseases

3. Water management Most Asian rice farms requires large amounts of water. An average of about 3000 L of water is used to produce 1 kilo of rice!

4. Water management ….. cont. The total average water use in irrigated lowland rice fields ranges from 675 mm to 4450 mm depending on the soil type, rice culture, and water management practices.

5. Infrastructure Input and outlet for water to flow in and to be drained out. 0% gradient (flat) – optimum Land must be levelled before planting. Bunds surrounding the field to contain water Minimum plot size 200 m x 50 m (1 hectare) Drainage density 40-50 m/ha Drain width 30 cm

9. Water quality & water need pH 4.5 – 8.5 salinity <1 dS/m Young seedlings (2 – 5 leaf stage) – should not be submerged Maximum depth 10 cm Lack of water, especially at panicle filling can reduce yield by 50% Flooding of rice is a method to control non-aquatic weeds.

10. Water management ….. cont. The components of water use in lowland rice fields i. During land preparation, most water used is lost by drainage through soil cracks..

11. Water management ….. cont. ii. Evapotranspiration To increase water productivity, must satisfy the evapotranspiration demand of the rice plant to enhance its full development and yield potential but with reduced total water input.

12. Water management ….. cont. iii. Seepage and percolation Seepage is the horizontal flow (lost) of water into or from a soil. Percolation is the downward movement of water through the soil.

13. Water management ….. cont. Irrigation techniques At least 3 methods are known can economically save water. 1. Continuous shallow flooding (CSF) 2.Alternate wetting and drying (AWD) 3.Saturated soil culture (SSC)

14. Irrigation techniques i. Continuous shallow flooding (CSF) Constantly 2 - 5 cm water in the field. Water is added when the depth is 2 cm. Irrigation is stopped at 10-15 days before harvest.

15. Irrigation techniques…. cont. ii. Alternate wetting and drying (AWD) Water is added to a depth of 2-5 cm but only after the fields have been dry for 2 to 7 days.

16. Irrigation techniques…. cont. iii. Saturated soil culture (SSC) The soil is kept as close to saturation as possible. This means irrigation is given to get 1 cm of floodwater but only 1 or 2 days after standing water is gone.

17. Water management

18. Water requirements at different plant growth stages Transplanting Tillering Panicle initiation Flowering Maturity Stage 1 Stage 2 Stage 3 Stage 4

19. Stage 1 Transplanting to tillering Vulnerable to water shortage. Insufficient soil water will cause retarded growth or even failure for seedlings to recover. 1 cm depth of water must be maintained.

20. Stage 2 Tillering to panicle initiation Physiologically, this is the most resistant growth stage to low soil water content. Soil water level should be kept as low as possible to accelerate tillering.

21. Stage 3 Panicle initiation to flowering Physiologically, this is the most susceptible growth stage to low soil water content. Soil water deficit will decrease no of grain per panicle, thus, reduce yield.

22. Stage 4 Flowering to maturity Water shortage during this period will further reduce grain yield. In general, drainage is done 15-20 days after flowering (heading) to hasten maturity and ripening of grains.

23. Water management Before I go splashing

24. End