1. PRIMARY, SECONDARY TILLAGE AND LAND MODIFICATION FOR RICE
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2. Abstract
Tillage is the most important operation to be carried out before take up sowing/ planting in rice.
Rice under different ecosystems:
Deep water
Upland rice cultivation
Wetland rice cultivation- 75% area in the world
Puddling :
Most important operation performed before sowing in wetland cultivation of rice.
It makes - soil amenable for rice cultivation
Providing better physical, chemical and biological situation suits to rice cultivation.
Floating rice
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3. Secondary tillage implements:
Primary tillage implements:
Mould board ploughs,Disc ploughs.
Sub-soilers Chisel ploughs.
Rotavators rotary tillers are used for rice cultivation.
Secondary tillage implements:
Disc harrow, cultivator.
puddler, bund former and planker
Animal drawn puddlers, power tiller operated puddlers, and tractor operated puddlers are mostly used for puddling rice fields.
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4. The main purposes of the tillage are,
Introduction
Tillage is the physical manipulation of the soil with tools and implements to result in good tilth for better germination and subsequent growth of crops.
The main purposes of the tillage are,
Soil pulverization which facilitates better root penetration and seedling emergence.
Cutting, incorporation and mixing of crop residues and vegetation into the soil to add humus and organic matter to the soil.
Improvement in moisture retention capacity by breaking the hard pan and crust formed on top layer of the soil.
Improvement in soil porosity and aeration.
Reduction in weed growth.
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5. Primary Vs secondary tillage: Primary tillage
Initial soil breaking ploughing and manipulating of top cm soil
It ensures burying of weeds and stubbles
Secondary tillage
Seedbed preparation and intercultural operations up to a depth of 15 cm.
It provides breaking of clods and mixing of crop residues.
After secondary tillage operation, the land is ready for sowing / planting.
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6. Deep water and floating rice Upland rice cultivation
Rice Ecosystem
Unlike many other crops, rice is gown in diverse land and water management systems throughout the world.
Deep water and floating rice
Upland rice cultivation
Wetland rice cultivation
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7. Deep water and floating rice cultivation
About 15% of world’s rice area - covered with deep water and floating rice cultures.
This method is the traditional method
In this system, tillage and seeding -done in dry soil before the onset of monsoon. Sometimes, land is repeatedly ploughed after seeding to control weed emergence.
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8. Upland rice cultivation
Dry seeding of rice is made into dry soil in the area having scanty rainfall.
Under this system, final land preparation is done with a harrow.
Crop is sown by a conventional seeder.
Labour requirement and yield – low
Irrigation requirement is high and weed management is more difficult compared to other methods of rice cultivation.
However, soil structure after rice harvest is more favourable for next crop under this system in comparison to wetland rice cultivation.
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9. Wetland rice cultivation
World’s rice is grown as 30% - rained lowland and about 45% - irrigated lowland.
Land may be prepared dry or wet, but, crop is always raised under standing water.
Under wetland cultivation (wet preparation), the soil is to be puddled and the crop is either directly sown or transplanted.
The highest yield is generally reported from wetland cultivation.
Therefore, a great prominence has been on development of suitable set of practices and machinery for wetland rice cultivation.
Paddy crop requires a large amount of water and hence, to reduce irrigation requirement, puddling is to be done in rice soils before sowing / transplanting.
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10. Puddling
Mechanical mixing of soil and water and allows the soil to settle at bottom to make soil less permeable.
At least 20% clay particles- puddling is effective
Most important and energy consuming operation under wetland cultivation.
Puddling leads to:
Increasing its water holding capacity due to increase in micro porosity of soil.
Makes manual transplanting easier by reducing shear strength of soil.
Reduction in air filled pore volume by replacing water.
Increase in moisture suction.
Better weed control due to lack of oxygen and shift in weed flora.
Improves soil fertility and productivity of the soil.
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11. Disadvantages of puddling
High water requirement (i.e. about 250 mm of water is needed), hindrance to regeneration of soil structure and impervious layer which impeded root development.
Puddling makes the soil chemically different from other soils.
A puddled soil system is characterized by presence of reduced soil layer and hard pans.
The degree of soil compaction, however, varies with soil type, cultivation practices, wetting and drying cycles, temperature and years of crop production
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12. Primary tillage
The main primary tillage implements used for rice cultivation are:
Mould board ploughs
Disc ploughs
Sub-soilers and chisel ploughs
Rotavators and rotary tillers
Mould board and disc ploughs - primary tillage implements preparation of paddy fields.
Sub soilers and chisel ploughs - not frequently used, because, impervious layer is important to hold more water under puddling.
Rotavator - very effective tillage implement
Uses of Rotavators:
Preparation- a fine seedbed.
Weed control, mixing of soil with crop residues.
This is also used in puddling operations.
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13. Secondary tillage implements:
Disc harrow – getting finer soil
Cultivator
Puddler
Bund former
Planker
The most realized implement - puddling - puddlers
Three types of puddlers: based on draught power, viz.,
Animal drawn,
Power tiller drawn and
Tractor drawn.
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14. Straight–blade puddler . Helical–blade puddler .
Animal Drawn Puddlers
Traditionally, puddling is done by operating a country plough under 5-10 cm of standing water.
Puddled soil quality is poor; water retaining capacity is low due to the un-puddled inverted ‘V’ shape area in the country plough.
To rectify the defect, improved bullock–drawn puddlers have been developed.
Some of these are:
Straight–blade puddler .
Helical–blade puddler .
Paddle type puddlers .
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15. Power tiller operated puddlers
Power tillers - mounted with cage wheels, rotavators and puddlers
Cage wheels are necessarily provided to reduce sinking of the unit and to develop sufficient traction required for operation of the power unit.
Working efficiency ha day-1.
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16. Tractor operated puddlers
Tractors fitted with cage wheels - used for puddling operation in rice cultivation throughout the world.
Puddling units used - tractors are straight–blade puddlers, cultivator or notched-disc harrow.
Puddling efficiency km hr-1 under 10 cm of standing water.
The effective field capacity of tractor–drawn puddlers varies from 1 to 2 ha day-1.
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17. Layout for seed bed preparation
Sectioning of field bunds and plastering
Corners of field are to be digging out which are not covered by ploughing or puddling.
About 2.0 cm of soil from top and sides of the bunds are cut-off to remove the weeds along with their seeds and to destroy the eggs of insect pests by using spade.
If the bunds are very broad
If rat burrows are noticed, pellets of 0.5 g or 0.6g Aluminum phosphide are inserted and the exit holes are plugged.
Mud paste to the sides and top of the bund to a thickness of 2.5 cm with a spade is applied and plastered using the flat surface of the spade.
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18. Partitioning the fields
Rice fields are to be divided in to smaller ( m2) area depending on the slope and water availability.
Small hand bunds with a size of 10 cm height and width are made using the mud.
These hand bunds increases growth of weeds due to non-stagnant condition.
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19. Summary
Tillage is the most important operation carried out in rice cultivation to get better production.
Tillage is generally divided into two, primary and secondary tillages.
Rice is grown in three different ecosystems such as, deep water and floating rice, upland rice cultivation and wetland rice cultivation. Among three, wetland rice cultivation is the predominant all over the world.
Puddling is ploughing the field in the presence of water to make impervious layer below the surface layer, is pre-requisite for wetland rice cultivation.
Among secondary tillage implements, puddlers are mostly used. Traditionally, animal drawn puddlers are in vogue, but, power tiller or tractor driven puddlers are highly useful for preparing rice fields due to high area coverage with less time and easy access.
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20. Assesment
Most predominant rice ecosystem in the world is wetland ecosystem and occupies 75% of total rice cultivable area (True/False)
Effective puddling is possible in the soils with at least 20% of clay content (True/False)
Puddling improves water holding capacity and ease transplanting (True/False)
Mould board plough and disc ploughs are important secondary tillage implements in rice cultivation (True/False)
Trimming and plastering operation reduces leaching losses of water besides controlling weeds (True/False)
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21. References
De Datta, S.K. and R.Barker Land preparation for rice soils. In: Soils and Rice. International Rice Research Institute, Los Banos, Philippines.
Narayana Rao, P.V. and B.S. Sirohi Comparative study of improved puddlers Journal of Agricultural Engineering. 12 (3-4):1-3.
Rajendra Prasad, A Text book of Rice Agronomy. Jain Brothers, New Delhi.
Yellamanda Reddy, T. and Sankara Reddi, G.H Principles of Agronomy. Kalyani Publisher, Ludhiana.
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