Harvesting and Threshing of Paddy Next. Introduction Cutting: cutting the panicles and straw....
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Transcript of Harvesting and Threshing of Paddy Next. Introduction Cutting: cutting the panicles and straw....
Harvesting and Threshing of Paddy
Next
Introduction
Cutting: cutting the panicles and straw.
Harvesting and Threshing of Paddy
Harvesting is the process of collecting the mature rice crop from the field.
Hauling: moving the cut crop to the threshing location.
Threshing: separating the paddy grain from the rest of the cut crop.
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Harvesting and Threshing of Paddy
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Good harvesting practices
Goals of good harvesting: maximize grain yield (minimize
losses) minimize grain damage Minimize quality deterioration• Heat build up from mold and
insect development• Discoloration/Yellowing from
heat build-up• Cracking from re-wetting of
dried grains• Loss of vigor
At harvest the quality of rice is the best. From then on it can deteriorate quickly due to:
Harvesting and Threshing of Paddy
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When to harvest
Harvest paddy at: 20-25% grain moisture 80-85% straw colored and the grains in the lower part of
the panicle are in the hard doe stage
30 days after flowering
Harvesting and Threshing of Paddy
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Harvesting systems
Manual operation, sometimes using tools
Labor requirement: 48 person days / ha
Harvesting and Threshing of Paddy
1. Manual system
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Harvesting systems
Labor requirement: 28 person days/ha
Capital cost (approx): Rs 45000
Harvesting and Threshing of Paddy
2. Manual cutting/machine threshing
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Harvesting systemsHarvesting and Threshing of Paddy
3. Machine cutting/machine threshing
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Optional:Winnowing or cleaning
Harvesting systemsHarvesting and Threshing of Paddy
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Cutting, hauling, threshing, cleaning in one combined operationCapacity: > 0.5 ha/hLabor requirement: 1 Operator
4. Combine harvesting
Harvesting and Threshing of Paddy
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Capacity: 0.07 ha/person dayAdvantageseffective in lodged crop less weather dependent
Manual cutting and hauling
ProblemsPlaces crop in window back in the fieldProblem with lodged cropComplex cutter bar and conveying mechanism
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Capacity: 2-4 ha/dAdvantages
Fast cutting
Manual cutting and hauling
ProblemsPlaces crop in window back in the fieldProblem with lodged cropComplex cutter bar and conveying mechanism
Harvesting and Threshing of Paddy
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Capacity: approximately 15 person days/ha
Threshing by impactHigh shattering lossesPre-drying might be needed
Manual threshing
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Capacity: Principle
Wire loop threshing drumMainly combing the grains off the straw, some threshing by impact
Pedal thresher
AdvantagesMaintains the straw
DisadvantageNeeds winnowing after threshing
Wire loop threshing drum
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Capacity: 0.3-3t/h• Threshing through impact• Large range of sizes
available• With or without cleaner• Truck mounted units
Axial-flow thresher
Advantages• Can thresh wet crop• Compact
Axial flow principle
Peg tooth threshing drum
Features capacity: 4-8 ha/day combines cutting, threshing,
cleaning and hauling tracks for mobility in wet fields
Advantages high capacity low total harvest losses
Disadvantages Requires relatively large field
sizes Problem in terraced fields
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Harvesting and Threshing of Paddy
Combine harvesting
Harvesting and Threshing of Paddy
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Capacity: 1ha/dayAdvantages
strips and collects grains onlyless material to handle
Stripper harvesting
Problemsproblems in wet soils and lodged cropstraw treatmentdoes not work well with long strawcomplex machineskills required
Despite strong promotion in SE-Asia the stripper harvester has not gained wide popularity because of its problems in less favorable harvesting conditions
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Harvest at the right time and moisture content
Recommendations for optimizing quality
Avoid stacking the cut crop in the field
Avoid delays in threshing after harvesting
Use the proper machine settings when using a threshing machine
Clean the grain properly after threshing
Avoid delay in drying after threshing
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Thresh as soon as possible after cutting
Tips for manual threshing
Hand thresh at lower moisture
Place a large canvas under the threshing frame to minimize shattering loss
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Thresh as soon as possible after cutting
Tips for machine threshing
Level the thresher
Set machine correctlydrum speeds in thresher (600rpm)air flow in the cleanerangle in the cleaner sieves
Setting threshing drum speed
Always 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.
RPM Tip speed (m/s) for drum diameters of
30 cm 40 cm 50 cm
400 6.3 8.4 10.42
450 7.07 9.4 11.78
500 7.85 10.5 13.09
550 8.64 11.5 14.4
600 9.42 12.6 15.7
650 10.21 13.6 17.02
700 11 14.7 18.3
750 11.8 15.7 19.64
800 12.6 16.8 21
850 13.4 17.8 22.25
900 14.14 18.85 23.6
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Setting concave clearance
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Concave clearance For 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.