Advantages and disadvantages
of harvesting green and dry kenaf stems |
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| Factors |
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Harvesting of green stems |
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Harvesting of dry stems |
| Loss of production |
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Generally minimum as the
crop remains in the field for a very modest period of time after having
reached maximum development in terms of yield. |
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They can be tall due to the
flattening of the plants or due to attacks of fungus that occur in the field
in poor weather conditions during the drying period. A partially dry crop can
reactivate the growth of the plants from the lowest nodes in the event of
rain. |
| Land
occupation |
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Minimum.
The crop can be harvested at the stage when it produces maximum yield per
unit of time. |
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The land is
occupied for a maximum of one or two months after the end of the development
stage, namely until such time as the plants are completely dry. |
| Post-harvest
processes |
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No problems
arise if the stems are used immediately by a paper mill. If, on the other
hand, they have to be stored, they must be dried after harvesting. |
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The process
and the storage at the paper mill are facilitated by the low humidity content
of the material that is delivered to the paper mill at the atmospheric dry
stage. |
| Juice from the stems |
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Part of the
juice contained in the stems can be extracted in the field. This restoration
of nutritional elements to the soil can also reduce the quantity of chemicals
required for the pulping process. The extraction of the juice from the stems
also facilitates the separation of the bast fibres from the woody ones. |
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The juice
of the stems cannot be recovered. |
| Efficiency of the operational capacity of harvesting |
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Higher
harvesting operational capacity is needed at peak times. This problem is
lesser in regions where production is possible all year round if the crops of
different farmers can be staggered over time. |
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As the time
of harvesting can be planned, based on requirements, there are more
opportunities to optimise the efficiency of harvesting operations. |
| Weight of harvested material |
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Heavy.
Green stems can be more than six times heavier than dry stems. For this
reason more heavy duty machinery is required. |
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Minimum, because the material is almost ready for being sold on the market. |
| Speed of harvesting |
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Reasonably
high. |
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Sometimes
low due to the frequent entanglements and consequent blocking of the
machinery. This problem can be overcome if harvesting machinery is designed
specifically for the harvesting of kenaf stems. |
| Environmental problems |
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None. But,
if it is not used a machine equipped with a cutting device to cut the apical
parts and pick up the leaves separately, then the plants should be defoliated
with drying products before harvesting. |
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Serious
potential problems due to: the transport of the herbicide mixing on the
nearby crops, the drying residual on
the ground and in the irrigation water, the harmful effects to the operators,
farmers and the population in general. |
| Leafy material |
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Can be used
as animal fodder. |
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Cannot be
recovered, but the dry leaves, scattered over the terrain restore nutritional
elements to the soil. |
| Other kenaf products |
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Integrated
process to produce seeds, leaf panels and potentially also the extraction of
the juice from the stems. |
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Only the
stems can be used for the production of cellulose fibres. |
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| Source: Kirshbaum M.U.F. - "Prospects for a Pulp and Paper
Industry in Australia" Department of Primary Industries and Energy -
Bureau of Rural Resources - Bulletin No. 9 1991. |
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