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RICE IN SRI LANKA-Water Management

Mitigation options

  1. Reduction of time taken for land preparation using total killing herbicides (e.g. Paraquat). This also reduces one tillage operation and conserve irrigation water.
  2. Dry sowing in well drain or sandy soils where water use is very high.
  3. Mulching straw after seeding to conserve moisture which also facilitates early and uniform seed germination and weed suppression.
  4. Careful plastering of bunds and “puddling” the field well to avoid rapid percolation and lateral seepage. This will also assure maintaining of standing water, without a requirement of frequent flooding.
  5. Utilizing the potential of existing rainfall for growing rice through timely cultivation It will also maximize irrigation water use efficiency.
    • Initial land preparation with the onset of rains will conserve irrigation water and assist ploughing deep which facilitate escaping terminal drought in longer duration varieties.
  6. Selection of a crop age class to suit the available water
    • Short aged varieties need low water requirement but at the expense of yield
    • The cost of land preparation and other agronomic practices would be the same or higher for short age varieties except a small decrease in use of fertilizers and pesticides
    • Short growing seasons demand better weed control and optimum timing which could increase cost of production
    • Very short duration (75 days) varieties (Bg 750) could be used in drought prone areas to avoid terminal drought but potential yield is rather low (70 bu/ac)
    • Kakulan type varieties with good weed competitive ability (e.g. 62-355) could be used in areas with short growing seasons.
  7. Rice does not require standing water to maximize yields. Maintaining saturated condition could save up to 40% of water in clay loam soils (IRRI, 1995) without yield reduction (weed control should be done separately)