Water management in irrigated rice - Rice Knowledge Bank ...

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Ponded water depth (mmm)15050TransplantingFloweringHarvest140 160 180–50200 220 240Day number–150–250–350Fig. 3.3. Depth of ponded water on the soil surface (above the horizontal line) and below the soil surface (below the horizontalline) in an AWD experiment, Tuanlin, Hubei, China. Adapted from Belder et al (2004).periods of dry soil and imposing a slight droughtstress on the plants, but this usually comes at theexpense of yield loss (Bouman and Tuong 2001).Research in more loamy and sandy soils with deepergroundwater tables in India and the Philippinesshowed reductions in water inputs of more than 50%coupled with yield loss of more than 20% comparedwith the flooded check (Sharma et al 2002, Singhet al 2002, Tabbal et al 2002).AWD is a mature technology that has beenwidely adopted in China (Li and Barker 2004). Itis also a recommended practice in northwest India,and is being tested by farmers in the Philippines.Figures 3.4 and 3.5 give an example of yields andwater inputs obtained by farmers in Central Luzon,Philippines, who practiced AWD irrigation (Lampayanet al 2005). The farmers used communaldeep-well pumps or their own shallow tubewellpumps to irrigate their fields. They divided theirfields into two, one with AWD management and theother with continuous flooding. Table 3.3 gives aneconomic comparison among AWD and continuouslyflooded fields. The AWD fields had the sameyield as continuous flooding, but saved 16–24% inwater costs and 20–25% in production costs.Very little research has been done to quantifythe impact of AWD on the different water outflowsof rice fields: evaporation, seepage, and percolation.The little work done so far suggests that AWDWater input (mm)1,4001,2001,0008006004002000Water input (mm)1,4001,2001,0008006004002000UpperDoloresMiddle2002 2003LowerAverageUpperMiddleLower2002 2003GabaldonAverageDoloresGabaldonAverageAverageFig. 3.4. Total water input (mm) under AWD (shaded columns)and continuous flooding (black columns) in farmers’ fields inTarlac (A) and Nueva Ecija (B), Philippines, 2002 and 2003dry seasons. Data from Lampayan et al (2005).AB21
Grain yield (t ha –1 )98A2002 200376543210UpperMiddleLowerAverageUpperMiddleLowerAveragemostly reduces seepage and percolation flows andhas only a small effect on evaporation flows. Belderet al (2007) and Cabangon et al (2004) calculatedthat evaporation losses decreased by 2–33% comparedwith fully flooded conditions.The following potential benefits of AWD havebeen suggested: improved rooting system, reducedlodging (because of a better root system), periodicsoil aeration, and better control of some diseasessuch as golden snail. On the other hand, rats find iteasier to attack the crop during dry soil periods.Yield (t ha –1 )982002B200376543210DoloresGabaldonAverageDoloresGabaldonAverageFig. 3.5 Average yield under AWD (shaded columns) andcontinuous flooding (black columns) in farmers’ fields inTarlac (A) and Nueva Ecija (B), Philippines, 2002 and 2003dry seasons. Data from Lampayan et al (2005).3.3.3 The System of Rice IntensificationAWD is the water management practice of theSystem of Rice Intensification (SRI), an integratedcrop management technology developed by theJesuit priest Father Henri de Laulanie in Madagascar(Stoop et al 2002). SRI is characterized by thefollowing practices (Uphoff 2007): Transplanting 8- to 12-day-old seedlings verycarefully (root tip down) Transplanting single seedlings Spacing the plants widely apart in a squarepattern (25 × 25 cm or wider) Controlling weeds by weeding with a rotatinghoe, which aerates the soil Applying compost to increase the soil’s organicmatter content (optional)Table 3.3. Average cost and returns of rice grown under AWD and FP (farmers’ practice = continuously flooded) in farmers’fields at three sites in Central Luzon, Philippines, in 2002 and 2003 dry seasons. Data from Lampayan et al (2005).ItemTarlac Nueva Ecija (Gab) Nueva Ecija (Dol)FP AWD FP AWD FP AWD2002Gross returns ($ ha −1 ) 933 933 1,183 1,292 1,073 1,043Production cost ($ ha −1 ) 441 397 1,030 870 597 574Net profit ($ ha −1 ) 491 535 152 422 477 469Net profit-cost ratio 1.1 1.3 0.1 0.5 0.8 0.82003Gross returns ($ ha −1 ) 1,134 1,105Production cost ($ ha −1 ) 519 491Net profit ($ ha −1 ) 615 614Net profit-cost ratio 1.2 1.222
Page 2: Water Management in Irrigated Rice:
Page 5 and 6: PrefaceWorldwide, about 79 million
Page 8 and 9: Fig. 1.2. Water balance of a lowlan
Page 10 and 11: given in Table 1.1. Water losses by
Page 14 and 15: Distribution (%)1009080706050403020
Page 16 and 17: The plant-soil-water system22.1 Wat
Page 18 and 19: Ψ Air-100 MPaDemandLeafXylemStemRo
Page 20: tive to water deficit than cell enl
Page 23 and 24: Water input (mm)4003503002502001501
Page 25: Table 3.1b. Yield, water input, and
Page 30 and 31: Table 3.5. Water input (I = irrigat
Page 32 and 33: Practical implementationTemperate e
Page 34 and 35: Practical implementationSpecific in
Page 36 and 37: Table 3.8. Comparison of water use
Page 38: Flooded yield (t ha -1 )87A65432102
Page 41 and 42: consumption (Hamilton 2003). Many t
Page 44 and 45: Irrigation systems55.1 Water flows
Page 46 and 47: the main system is supply-driven, f
Page 48 and 49: Table 5.1. Area, water use, and tot
Page 50 and 51: Appendix: InstrumentationDetailed d
Page 52: 0.5 cm in diameter and spaced 2 cm
Page 55 and 56: Bronson KF, Singh U, Neue HU, Abao
Page 57 and 58: Lampayan RM, Bouman BAM, De Dios JL
Page 59: Uphoff N. 2007. Agroecological alte

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