Bangladesh: Ribon Retting of Jute and it’s importance

Bangladesh: Ribon Retting of Jute and it’s importance

Anumber of methods have been developed and recommended for the improvement of

fibre quality through retting. For retting gently flowing, fairly deep, clear and soft water

is ideal. The optimum temperature is around 34°c, ditches, tanks, beels-haor or in vast

water are also used for retting. After bundles of jute are

kept in retting water and placed side by side with 2/3 layers

in such way that there remains ample space for the easy

movement of water and microbes. Later these are covered

with water-hyacinth, rice straws or any kind of aquatic

weeds etc. The float/jack is then weighed down with

concrete blocks or are kept submerged (at least 10 cm

below the surface water) with bamboo crating. Earth

chunk, logs of banana, mango tree or any other green logs as covering or weighing

materials should be avoided as they convert the fibre colour dark (shamla). In that case

polythene-wrapped earth chunks can be used safely as it protects the plants to come in

contact with clay. For accelerating the retting speed and improving the fibre colour, about

one kg of urea may be applied in 1000kg of green jute plants. The urea may be added

either in a water solution or sprinkled directly in the layers of the jute bundle in jute jaks.

Retting is a microbiological process and, therefore, the end-point is determined by

inspecting a few plants each day from the tenth day onward. If fibre slips out easily from

the wood on pressure from the thumb and fingers, retting is considered complete.

Fibre Extraction

The fibres can be extracted from the retted plants in two

ways: (1) by taking one or two plants at a time sitting on

the dry land or (2) by standing in knee-deep water and

using a bamboo frame, a bunch of plants is taken out of the

jak and the fibres are extracted from the whole bunch at a

time by breaking the jute sticks at about 45cm from the

bottom. In either of the two ways, if the bottom parts of the

Jute harvesting

Retting process

Fibre Extraction

retted plants are scraped off by hand prior to extraction or beaten with a wooden beater

the amount of cuttings are reduced significantly. Better fibres are obtained if extraction of

fibres is done on the ground taking single or two plants at a time.After extraction, the

fibres are washed thoroughly in clean water so that broken jute sticks, cuticular layer of

barks, clay or any other dirts get free from fibres.

Removal of Shamla Colour (Dark Colour)

The shamla fibre (if produced due to improper practices) could be converted to bright and

normal fibre if they are immersed in 2.5% Tamarind water solution or Acid mixture

(0.25% sulphuric acid, 0.25%. hydrochloric acid and 0.6% oxalic acid). But the treated

fibres should be well washed in clean water so that no trace of Tamarind or acid solution

is left in the fibres. Otherwise fibre quality deteriorates at storage.

Drying of Fibres

After washing, the fibre should be dried well in a bamboo frame

or by hanging in any way, so that it does not come in contact

with mud or dust. Fibers should not be dried spreading on the

ground. Mud or dust not only lowers the quality of the fibre but

also creates health hazards to jute mill workers.

Ribboning and Ribbon Retting

In Bangladesh, jute grows very well and sufficient water needs to be retted for quality

fibre. But insufficient retting water produces poor quality fibre. It is also observed that

due to environmental changes rainfall does not occur in season time for retting. As a

result unavailable rainfall during the rainy season in jute

growing areas of Bangladesh, often forces the farmers to

keep the jute plants in low volume of muddy water ponds,

cannels leading to improper retting and inferior quality fibre.

In some cases, jute plants are getting dried in the field itself

giving no monetary benefit to the resource poor jute farmers.

To solve this retting water problem BJRI has developed a

number of ribbon retting methods, which are hand rebboning

with bamboo hook, roller ribboner and recently developed

power ribboner. Through this technique ribbons (bark of

plants) can be very easily separated out from the woody core

in green stage (just after harvest).

Before retting, ribbons should be arranged into ring form. If

retting water is not available in the nearby places, ribbons

may be retted in big earthen vats, filled with clear water. One

may ret 30kg of ribbons in one of such big earthen vats.

If shallow small pond/ditches or canals are available in the

nearby places, the ribbons may be retted by putting the ring

of ribbon in a bamboo pole and steeping under water tying

Drying of Fibres

Ribbon retting method

with two bamboo poles fixed in the bottom of the pool. Retting may be conducted in

artificially made small ditches dug around homestead of the farmers or in jute field

covering the ditches with polythene sheets. The ditches may be filled with clear water

from tube well or from any other water sources.

Advantages of Ribbon Retting:

• Lesser amount of water is required for retting.

• The quality of fibre improves.

• The jute sticks remain stronger since it is not retted.

• Minimum transportation cost is involved.

• Cutting free better quality fibre fetches better price.

Seed crop harvesting and post harvest processing

The seed crop becomes ready to harvest between mid October to mid December when 60-

70% capsules/fruits become brown in colour in sunny dry. The harvested tops should be

dried in sun for 4-5 days to bring it into threshing condition. Drying in the oven at 56ºC for

24 hours has found suitable for jute seed to bring its moisture content below 10%.

However, it is not applicable to farmers’ level. Jute seed should be dried 3-6 (for 8 hours a

day) days in sun. This could help retain seed moisture content between 7-9% which is the

most safe moisture level for storage of jute seed.

Seed preservation

Seeds preservation is influenced by the moisture content of seed, temperature and relative

humidity which are related to the seed viability and germination for sowing. Jute seeds are

delicate to lose their viability sharply if they are not stored properly. Jute seeds are harvested

in October to November and Novemberto December for Corchorus capsularis and Corchorus

olitorius respectively. Freshly harvested jute seeds have a high moisture content which is

estimated about 20-25 percent. This content of moisture of seeds is harmful for preservation.

So, that after threshing of jute, seeds moisture needs to be reduced to 7-9 percent by 4-6

sunning (6 hrs. a day). Even jute seed having moisture below 7 percent may be stored for

about two years. It is noted that after each days sunning the seed should be cooled and stored.

Beside, storage temperature also plays a vital role for seed viability and vigour. Sobhan and

Khatun (1986) reported the effect of moisture content on jute (Corchorus spp.) kenaf and

mesta seeds at storage temperature +200 C, +40 C and -200 C respectively upon viability and

vigour. Storage at room temperature jute seeds with 4.0% to 7.75 moisture maintained above

80% viability up to 12 months of storage, the mesta seed maintained 80% viability up to 6

months of storage with 5.3 % to 7.5% moisture.

Storage condition plays a significant role in seed preservation. Storage containers having

semipermeable to non-permeable status may be noted worthy for short term as well as

long term seed preservation. Seed grower at farm level use different types of containers.

The farmers of Bangladesh use four types of containers which are metal, clay pot,

polythene bag, jute sacks. The storage efficiency of clay pot and jute sacks is permeable

to relative humidity. Therefore, the tin container and non-permeable plastic container are

suitable for long time preservation with cool and dry storage condition.

Cylindrical internodes, ovate shape bud, outer

auricle transitional-2 and inner auricle transitional-1.

Resistant to red rot, slightly susceptible to borer and

tolerant to water logged condition. It is mid maturing

variety. Sugar in canes 12.97%. Cane yield: 79 t/ha.

Duration: 360-400 days.

Cylindrical internodes, eye bud rectangular. Bud

groove clear. Outer auricle deltoid and inner auricle

long lanceolate. Moderately resistant to red rot and

borers. It is early maturing variety. Sugar in

canes14.48%. Popular for sugar and gur (jaggery)

production. Cane yield: 92 t/ha. Duration: 350-390

days.

Conoidal shape internodes, eye bud triangular and

overlap on growth ring. Outer auricle dentoid and

inner auricle deltoid. It is mid maturing variety.

Resistant to red rot, moderately susceptible to borer

and tolerant to water logging condition. It can be

grown in the low lying areas. Sugar in canes

13.48%. Cane yield: 72 t/ha. Duration: 360-390

days.