Harvesting and Threshing of Paddy

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Harvesting and Threshing of Paddy. Dr. J. P. Sinha and Dr. S. K. Jha Indian Agricultural Research Institute New Delhi 110 012. Content. Introduction What is harvesting Harvesting systems When to harvest How to harvest (technology options) Recommendations. Introduction. - PowerPoint PPT Presentation

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  • DR. J. P. SINHA and DR. S. K. JHA INDIAN AGRICULTURAL RESEARCH INSTITUTENEW DELHI 110 012Harvesting and Threshing of Paddy

  • ContentIntroductionWhat is harvestingHarvesting systemsWhen to harvestHow to harvest (technology options)Recommendations

  • IntroductionHarvesting is the process of collecting the mature rice crop from the field. Cutting: cutting the panicles and straw.Hauling: moving the cut crop to the threshing location.Threshing: separating the paddy grain from the rest of the cut crop.

  • Good harvesting practicesGoals of good harvesting:maximize grain yield (minimize losses)minimize grain damage Minimize quality deteriorationHeat build up from mold and insect developmentDiscoloration/Yellowing from heat build-upCracking from re-wetting of dried grainsLoss of vigorAt harvest the quality of rice is the best. From then on it can deteriorate quickly due to:

  • When to harvestHarvest paddy at:20-25% grain moisture80-85% straw colored andthe grains in the lower part of the panicle are in the hard doe stage 30 days after flowering

  • Harvesting systems1. Manual system Manual operation, sometimes using toolsLabor requirement: 48 person days / ha

  • Harvesting systems2. Manual cutting/machine threshingLabor requirement: 28 person days/haCapital cost (approx): Rs 45000Optional: Winnowing or cleaning

  • Harvesting systems3. Machine cutting/machine threshingOptional: Winnowing or cleaning

  • Harvesting systems4. Combine harvestingCutting, hauling, threshing, cleaning in one combined operationCapacity: > 0.5 ha/hLabor requirement: 1 Operator

  • Manual cutting and haulingCapacity: 0.07 ha/person dayAdvantageseffective in lodged cropless weather dependentProblemshigh labor costlabor dependent, competes with other operations in peak seasonwinnowing/cleaning necessary

  • Mechanical reapingCapacity: 2-4 ha/dAdvantagesFast cuttingProblemsPlaces crop in window back in the fieldProblem with lodged cropComplex cutter bar and conveying mechanism

  • Manual threshingCapacity: approximately 15 person days/haThreshing by impactHigh shattering lossesPre-drying might be needed

  • Pedal thresherCapacity: PrincipleWire loop threshing drumMainly combing the grains off the straw, some threshing by impactAdvantagesMaintains the strawDisadvantageNeeds winnowing after threshingWire loop threshing drum

  • Axial-flow thresherCapacity: 0.3-3t/hThreshing through impactLarge range of sizes availableWith or without cleanerTruck mounted unitsAdvantagesCan thresh wet cropCompact

    Peg tooth threshing drumAxial flow principle

  • Combine harvestingFeaturescapacity: 4-8 ha/daycombines cutting, threshing, cleaning and haulingtracks for mobility in wet fieldsAdvantageshigh capacity low total harvest lossesDisadvantagesRequires relatively large field sizesProblem in terraced fields

  • Stripper harvestingCapacity: 1ha/dayAdvantagesstrips and collects grains onlyless material to handleProblemsproblems in wet soils and lodged cropstraw treatmentdoes not work well with long strawcomplex machineskills requiredDespite strong promotion in SE-Asia the stripper harvester has not gained wide popularity because of its problems in less favorable harvesting conditions

  • Recommendations for optimizing qualityHarvest at the right time and moisture contentAvoid stacking the cut crop in the fieldAvoid delays in threshing after harvestingUse the proper machine settings when using a threshing machineClean the grain properly after threshing Avoid delay in drying after threshing

  • Tips for manual threshingThresh as soon as possible after cuttingHand thresh at lower moisturePlace a large canvas under the threshing frame to minimize shattering loss

  • Tips for machine threshingThresh as soon as possible after cuttingLevel the thresherSet machine correctlydrum speeds in thresher (600rpm)air flow in the cleanerangle in the cleaner sieves

  • Setting threshing drum speedAlways adjust the thresher correctly. For peg-tooth drums the drum tip speed should be about 12-16 m/sec (see Table for correct RPM).Higher speeds result in higher grain damage and de-hulled grains. Lower speeds increase the amount of non-threshed grain and result in grain loss. Lower speeds also decrease the throughput of the thresher.

    RPMTip speed (m/s) for drum diameters of 30 cm40 cm50 cm4006.38.410.424507.079.411.785007.8510.513.095508.6411.514.46009.4212.615.765010.2113.617.027001114.718.375011.815.719.6480012.616.82185013.417.822.2590014.1418.8523.6

  • Setting concave clearanceConcave clearanceFor most threshers clearances between peg-teeth and concave should be about 25mm. Smaller clearance increases grain damage and might lead to clogging of straw. Larger concave clearances reduce threshing efficiency.

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