Rice Technology Bulletin Series

1 Released Rice Varieties (1968-1994)2 Pagpaparami at Pagpupuro ng Binhi

sa Sariling Bukid3 Paggawa ng Maligaya Rice Hull

Stove4 PhilRice Micromill5 PhilRice Flourmill6 PhilRice Drumseeder7 PhilRice Rototiller8 Rice Food Products9 PhilRice-UAF Batch Dryer10 Integrated Management of the

Malayan Black Bug11 SG800 Rice Stripper-Harvester12 Dry-Seeded Rice-Based Cropping

Technologies13 Maligaya Rice Hull Stove14 10 Steps in Compost Production15 Rice Tungro Virus Disease16 The Philippine Rice Seed Industry

and The National Rice SeedProduction Network

17 10 Hakbang sa Paggawa ngKompost

18 10 nga Addang ti Panagaramid itiKompost

19 Characteristics of Popular PhilippineRice Varieties

20 Rice Stem Borers in the Philippines21 Rice Food Products (revised edition)22 Leaf Color Chart (English)23 Leaf Color Chart (Ilocano)24 Leaf Color Chart (Filipino)25 Equipment for Rice Production and

Processing26 Use of 40kg Certified Seeds per

Hectare27 Rice Wine28 Management of Field Rats29 Controlled Irrigation: A Water-Saving

Technique for Transplanted Rice

30 Minus-one Element Technique:Nutrient Deficiency Test Made Easy

31 Management of the Rice Black Bug32 Management of Zinc-deficient Soils33 Management Options for the

Golden Apple Snail34 Use of Evaporation Suppressant35 Pagpaparami ng Purong Binhi ng Palay36 Management of Sulfur-Deficient Lowland

Rice Soils37 Management of Planthoppers and Leafhoppers38 Management Options for Ricefield Weeds39 Use of Indigo as Green Manure40 Management of Salt-affected Soils for Rice

Production41 Wet-Seeded Rice Production42 Matatag Lines43 Hybrid Rice Seed Production44 Metarhizium anisopliae: Microbial Control

Agent for Rice Black Bug45 Integrated Nutrient Management for Rice

Production46 Management of Armyworms/Cutworms47 Carbonized Rice Hull48 Rice-based Microbial Inoculant49 Integrated Farm and Household Waste

Management50 Rice Postproduction Practices51 Ecological Rice Farming52 Modified Dry Direct Seeding Technology53 Palayamanan: Making the Most Out of Rice

Farms54 Practical Guidelines in Predicting Soil Fertility

Status of Lowland Rice Soils55 Bakanae: The Foolish Disease of Rice

56 Management of Rice Blast Disease

57 Root-knot Management in Rice-Onion CroppingSystem

58 Management of White and Yellow Stemborers

Foreword

Water is essential to the growth of the rice plant. Under an idealcondition and with good farm management, lowland rice requiresaround 2,000 liters of water to produce one kilogram of rice at100 cavans per hectare yield. Farmers, however, use more. Theyapply irrigation water continuously from land preparation to thehardening of grains. Estimates show that up to 4,000 liters ofwater is usually used for a kilogram of rice in most Philippine ricefarms. But with irrigation water now becoming costly and scarce,it is important to develop schemes that can reduce the amountof water used in irrigated lowland rice without reducing yield.

This technology bulletin offers a practical technique on how tosave irrigation water without decreasing rice yield. If farmersnear irrigation sources use water efficiently, more farms near thetail-end of an irrigation system might be benefited. For thoseusing water pump, this technique will help increase the farmers’income through reduction of farm inputs such as oil, fuel, andlabor.

Technical knowledge on water-saving techniques, importance ofwater control structures on the distribution channels, farmditches, and dikes that facilitates water conveyance and controlwithin the farm are being adressed by this Bulletin.

We acknowledge our partnerships with International RiceResearch Institute (IRRI), National Irrigation Administration(NIA), and various local government units in developing thistechnology. I hope this bulletin will guide other staff of ourpartners in promoting this very important technology.

LEOCADIO S. SEBASTIANExecutive Director

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Introduction

From land preparation to last irrigation, a field area of one squaremeter that usually yields 0.5 to 0.75 kg rice consumes around 2,000liters or 10 drumfull of water. How-ever, farmers tend to continuouslyflood their fields and use 15 to 20drumfull of water to maintain apaddy water level higher than 7 cm.They do this to store more water,reduce the frequency of field visits,and because of their belief thatmore water controls more weeds.However, continuous flooding andfield water level higher than 7 cmresults in too much percolation,seepage, and even run-off. It causesdelayed growth and reduced tilleringbecause of impediment in rootdevelopment caused by reducedoxygen level within the root zone.

Continuous flooding also triggers some yield-reducing factors suchas too much leaching, soil nutrient imbalance (zinc deficiency),lodging problems owing to weak base and anchorage of the plant,and environmental problem such as global warming due to highmethane gas emission. This also results in lesser and untimely waterin the fields near the tail-end, high water-use in gravity irrigationsystems, and too much water cost in pump irrigation systems.

Results of studies on water-saving irrigation techniques fortransplanted and direct-seeded lowland rice show that continuousflooding is not necessarily required by rice to produce good yield.These studies resulted in a technique called controlled irrigation,which show that water can be controlled to reduce farm inputs andat the same time help the plant grow healthier.

Rice plants with excessive water.

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Benefits

Reduces water usedin rice production by16-35% withoutdecreasing grain yield

Aids in proper seedgermination andseedling survival,tillering, and grainuniformity

Increases theefficiency of theplants in using soilnutrients and appliedfertilizers

Keeps a good balanceof available nutrientsin the soil

Helps in controllingweeds

Controlled Irrigation can make harvesting somuch easier.

Field trial at PhilRice Central Experiment Station, 2007 DS, showedthat the performance of a combine harvester is more efficient in a fieldwith Controlled Irrigation (CI) than in a Continuously Flooded (CF)field. The stable soil condition under CI facilitates the operation of themachine and makes harvesting faster.

Minimizes golden apple snailattack since there is anexcellent water levelcontrol

Significantly reduces cost inpump irrigated areas

Stabilizes soil and plantbase, hence helps minimizecrop lodging

Facilitates farmmechanization especially inthe harvesting and haulingof harvests

Reduces farm inputs suchas oil, fuel, and labor

Provides for timely waterneeds of farms at the tail-end of an irrigation system

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Target Users

1. Farms with limited water supply or those farms withsupplemental irrigation such as the following:

near tail-end of an irrigation system

using small water impounding systems

using small farm reservoir

using communal irrigation systems

using pump irrigation system (shallow tube or deep well)

2. Farms near main canals with the following circumstances:

unstable plow layer or hard pan that causes difficulty in landpreparation, harvesting and hauling

nutrient imbalances such as zinc and sulfur deficiencies

poor root growth due to accumulation of excessive organicacids from decomposing materials due to insufficient soilaeration

Important Considerations in Irrigating

1. Method of planting

Transplanted (common during wet season and in places wherecontrol of water is difficult)

Direct Seeded (lesser water is used in direct seeding speciallydry seeding)

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2. Season of planting

Dry season (more irrigation water is needed)

Wet season (less frequent irrigation)

3. Soil texture or soil type

Fields with clayey (fine-textured) soil have longer pond-water retention, usually 3-5 days at 5 cm initial depth.Hence, irrigation is less frequent.

Fields with loam to sandy loam (medium-to-course-textured) soil retain pond water for less than 12 hours.Hence, irrigation is more frequent. However, pond-waterdepth should be kept only in minimum, 2-3 cm, duringirrigation to decrease water losses.

The “feel method” can be used to determinethe textural class of a soil. Soil samples aremoistened and rubbed between the thumb andthe fingers.

(A) Fine-textured soil - sticky, cohesive, andforms a ribbon after pressing and rubbing.Examples are clay, clay loam, silty/sandy clayloam.

(B) Medium-textured soil - less cohesive,feels gritty, and does not form a rigid ribbonafter pressing and rubbing. Examples areloam, silt loam, and sandy loam.

(A)

(B)

How to Determine the Texture of a Soil

Pre-planting techniques

1. Fix farm dikesand ditchesbefore or duringthe first irrigationor before theonset of rainyseason.

2. Use appropriateplanting methodbased on wateravailability andability to controlit.

3. Plow immediately after the first irrigation. Do not allownewly irrigated fieldto stand unplowedfor several days.

4. Use just enoughirrigation waterduring landpreparation tofacilitate soilpuddling, organicmatterdecomposition, andland leveling.

5. Establish and level the field very well. There should beuniform water distribution in the whole paddy at 2-3 cmdepth of pond water.

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6. Shorten land preparation time to one to two weeks fornon weedy or dry-plowed field, until three weeks forfields with fresh rice stubbles, and four weeks for fieldswith much weeds and stubbles.

7. Apply minimal irrigation water, about 2-3 cm until 30 daysafter planting. This will promote better seedlingestablishment and weed control.

8. When using a herbicide during the first month, follow thewater management scheme required by the herbicidebeing used.

Post-planting procedures

1. Maintain 2-3 cm water depthfrom planting up to onemonth. This will help theseedlings survive and this willhelp control weeds.

2. Apply controlled irrigationtechniques by using anobservation well. Thisfacilitates the monitoring ofwater status in the field andhelps determine the righttiming of irrigation.

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Controlled Irrigation using Observation Well

Making the observation well

1. Make an observation well outof a plastic tube or bamboothat is 25 cm long with atleast 10 cm diameter. Whenusing a bamboo, make surethere is no node within thecut material.

2. Designate one end of thetube as “top”. From thetopmost part of the tube,make a circumferential markat 5 cm and 10 cm and labelthem with “wet season” and“dry season”, respectively.

3. Using a manual or electricdrill with 3-5 mm diameter,make holes every 3 cmhorizontally or length wise.

4. On the other hand, keep a 5cm distance between holesvertically or cross wise.

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Installing the observation well

5. After planting, select a representative site in your fieldwherein the observation well can be installed. An ideal site islocated around 1-2 m from paddy dike to facilitate regularobservation of the paddy water.

For farms with uniform conditions among paddies, only oneobservation well per hectare is needed. On the other hand,farms with heterogeneous condition or paddies with differentsoil texture or elevation need one observation well percategory (soil textureor elevation).

6. In the selected site,press the tubevertically against theground as much asyou can then pull itback completely.

7. Remove the soil insidethe tube after liftingit above the ground bydownpouring the soilinside.

8. Repeat step 6 and 7until the marker “wetseason” or “dryseason” in the tube isexactly leveled againstthe ground surface.

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9. Fix the observation wellvertically and check ifthe label for a givenseason (wet season ordry season) is leveledagainst the ground.

Using the observation well

10.When irrigating duringthe wet season, floodthe field until thewater reach thetopmost portion of thetube. On the otherhand, during the dryseason, flood the fielduntil the water reach 5cm above the groundor the circumferentialline marked with “wetseason.”

11. Irrigate again using thecontrolled irrigationwhen there is no morevisible water in theobservation well.

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Dry SeasonWet Season

Important Reminders

Start irrigating the field based on the observation well 30days or four weeks after planting. At this time, seedlingsare well established and the primary weed control measureswere executed already.

Start irrigating in the afternoon, around 3-4 PM, to minimizeevaporation losses and to take advantage of cooler irrigationwater.

During the tillering period, the rice plant and soil are healthyif there is enough oxygen to balance the various physico-chemical and biological activities in the rhizosphere, hence donot flood continuously.

During flowering, maintain 5 cm depth of standing water inthe paddy to avoid the development of unfilled grains due tolack of water.

Last irrigation should be one week before harvest for light-textured soil and two weeks before harvest for heavy-textured soil.

Practice shallowrotavation afterharvesting. Thishelps conserveresidual moistureand minimizes thedevelopment ofwide and deepcracks during dryseason fallow.

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REFERENCES

Bouman BAM, Hengsdijk H, Hardy B, Bindraban PS, Tuong TP, Ladha JK,editors. 2002. Proceedings of the International Workshop on Water-WiseRice Production. 8-11 April 2002. IRRI Los Baños, Philippines. 356 p.

Cuyno RV, BAM. Bouman, RM Lampayan, DF Tabbal, MB Quiamco, ATLactaoen, T M Norte, EJP Quilang, and JL de Dios. 2002. TechnologyTransfer or Transformation Process? Initial Insights from the “TechnologyTransfer for Water-Savings” Project in Central Luzon, Philippines. Water-Wise Rice Production. 8-11 April 2002. International conference. IRRILos Baños, Philippines.

De Dios JL. 2004. Promising Water-Saving Techniques for Irrigated LowlandRice in the Philippines. In Redoña ED, Castro AP, Llanto GP, editors.Rice Integrated Crop Management: Towards a RiceCheck System in thePhilippines. Proceedings of the National Workshop on Rice IntegratedCrop Management May 4-5, 2004. Philrice Science City of Muñoz, NuevaEcija. Philrice 191 p.

De Dios JL, EJP Quilang, AA Corpuz, AJ Espiritu, MD Malabayabas, ACArocena, LF Ramos, JG Ignacio, LD Esteban and MI Liwanag. 2000.Response of Philippine Released Rice Varieties to Different Water-SavingIrrigation Schemes. Philippine Agricultural Mechanization Bulletin. Vol.VII No. 1. 1st & 2nd Quarter Issue 2000. College of Engineering andAgro-industrial Technology University of the Philippines Los Baños,Laguna.

De Dios JL and EF Javier. 2000. Intermittent Irrigation: A New Approach to aBetter Water Management. In CECAP and PhilRice. 2000. HighlandRice Production in the Philippine Cordillera. CECAP, Banaue Ifugao andPhilRice, Maligaya Munoz, Nueva Ecija.

Lampayan RM, Bouman BAM, JL de Dios, AT Lactaoen, AJ Espiritu, TMNorte, EJP Quilang, DF Tabbal, LP Llorca, JB Soriano, AA Corpuz, RBMalasa, and VR Vicmudo. 2004. Adoption of Water Saving Technologiesin Rice Production in the Philippines. Extension Bulletin 548. Food andFertilizer Technology Center. PO Box 22-149 Taipei City, Republic ofChina on Taiwan.

Published 2007 by the Philippine Rice Research Institute. 1st printing -3,000 copies

Copyright © 2007

Subject Matter SpecialistsJovino L. de DiosAlex J. EspirituEvelyn F. JavierMelanie Aileen T. CantreKristine C. SamoyEduardo Jimmy P. Quilang, PhD

Managing Editor/Layout ArtistHazel V. Antonio

Editorial AdvisersLeocadio S. Sebastian, PhDSosimo Ma. Pablico, PhDDiadem B. Gonzales

For more information, contact:

Philippine Rice Research InstituteMaligaya, Science City of Muñoz, Nueva Ecija 3119

Text (0920) 911-1398 or using your SMART cellphone, typePALAY<space>INFORICE <space>QUESTION and send to700RICE (7007423)