Achieving self-sufficiency in natural rubber | Sunday Observer

Achieving self-sufficiency in natural rubber

Rubber plants with good ground cover.
Rubber plants with good ground cover.

Natural rubber is a commodity in which the potential for value addition is at a very much higher level than any of the other commodities.

Adding value and exporting against exporting of raw rubber enhances foreign exchange earnings to the country whilst generating more employment opportunities. The rubber product manufacturing sector in Sri Lanka has shown remarkable growth in recent years.

Today, the rubber product manufacturing sector of the country needs around 135,000 metric tons of natural rubber per annum. However, the country is not able to produce this quantity of natural rubber compelling to import around 66,000 metric tons of natural rubber to the country annually (Table 1). Sri Lanka spends around Rs. 16 billion to import natural rubber to bridge the supply and demand gap of the country.

This trend while creating pressure on the country’s limited foreign  exchange reserves is also a hindrance for the development of the natural  rubber industry in the country. Thus,  there is an urgent need for relevant stakeholders of the industry to  endeavor towards making Sri Lanka self-sufficient in its natural rubber requirement.

Natural rubber production

The total extent and productivity together determine the rubber production ofany country. In Sri Lanka the area under rubber cultivation has shown a declining trend from 133,100 ha in the year 2014 to 126,700 ha in the year 2018 (Table 2).

Though land productivity stood at 914 kg/ha/year in 2014 it too had  gradually declined to 853 in 2018 (Table 2). The declining trends in  both factors that determine total production, i.e. land extent and  productivity, from 2014 to 2018 have led to the declining trend in our  total production as well during the same period.

As a short-term strategy increasing productivity of rubber lands and as a long-term strategy increasing the land area through establishing rubber cultivations having high yield potential need to be implemented. to arrest this declining trend in natural rubber production.,

Why is land productivity low?

As per the planting density recommended by the Rubber Research Institute of Sri Lanka,around 520 rubber  plants should be planted in a land extent of one hectare. If all 520  plants in a hectare of land are vigorously growing and healthy, each  plant will have the potential to yield around five kilograms of dry rubber per annum at maturity except during the initial two-three years of tapping. To harvest this potential 5 kilograms of dry rubber  from a plant the quality of harvesting/tapping has to be good and also  harvesting should be undertaken uninterruptedly during each year.

With a possible 340-350 days of harvesting per annum, the number of  tappings on a single tree would be either around 172 or 115 for once in  two (d/2) and three (d/3) day tapping systems respectively.If these  factors governing yield is achieved it is apparent that the potential  from rubber cultivations is around 2,600 kilograms of dry rubber  per hectare per annum during peak yielding periods which is around 300%  more than the current national land productivity level of 853 kilograms  of dry rubber per hectare per annum (Table 2).

However, 100% of the potential yield stated  above cannot be practically achieved under commercial conditions.  Uncontrollable factors such as heterogeneity in soil conditions and  adverse climatic conditions contribute to deviations. Controllable  factors such as lapses in management, availability and skill levels of  workers including harvesters and levels of adopting good agricultural  practices also leads to deviations from potential performance. The level  of actual performance in rubber cultivations we witness today partly reflects the deviations from good agricultural practices recommended to the growers. 

Though the rubber growers’ plant 520  plants in a hectare of land, the average number of plants remaining at  the time of commencement of tapping which is generally six-seven years  after planting is found to be around 460. Use of poor-quality plants,  incorrect technique of planting, adverse weather for planting, lightning  damage, leaf and root diseases and animal damages largely contribute  to this reduction in stand per hectare. The loss of stand per hectare  continues even after commencement of harvesting.

Surveys have revealed that the loss of stand per hectare could be as  much as 0.75% per annum during the 24-year tapping cycle of a rubber cultivation. This would mean that at the end of the economic lifespan of a rubber  cultivation,on average the remaining stand will be around only 380  plants per hectare. Another significant factor that lowers land  productivity is the physiological disorder Tapping Panel Dryness (TPD).

Trees affected with tapping panel dryness though look healthy would  not yield any latex upon tapping using recommended tapping systems. At  the commencement of tapping all the 460 plants (the average number of  plants present in a hectare at the time of tapping) will yield. However,  each year the number of trees that would get affected with TPD will  increase and towards the end of the 24-year tapping cycle it could be as  high as around 25%. Thus, at the end of the tapping cycle the number of  yielding rubber trees present in a  hectare of land would be only around 285, i.e. 25% less from 380.

Accordingly, the average number of yielding trees during the 24-year  tapping cycle will be 373 {(460+285)/2}. If the potential five kilograms of rubber  per tree per annum could be achieved from this number of trees the  average land productivity during the 24-year tapping cycle would be  1,865 (373 * 5) kilograms per hectare per annum. This is a 30% reduction  of the potential land productivity of 2,600 kgs per hectare per annum.  Thus, what is apparent is that lowering of productive rubber stand per hectare due to various reasons identified above alone reduces the land productivity by about 30% from the potential.

Commencement of tapping at the correct vegetative growth stage of  the plant and use of chemical fertiliser as recommended by the Rubber Research Institute are also factors essential to build tree vigor and obtain five kilograms of dry rubber  per tree per annum. However, commencement of tapping prior to reaching  the correct growth stage and deviations in the use of chemical  fertiliser can often be observed in rubber  cultivations. In average this reduces the yield potential per tree per  annum from five to around four kilograms further lowering the land productivity  from 1,865 to 1,492(4 x 373) kilograms per hectare per annum.

Due to deviations from the expected level of management and adoption of agricultural practicesthe yield potential of a rubber  tree could drop to 4 kilograms from 5 kilograms per tree per annum as  discussed. Another condition that we need to fulfill even to obtain 4  kilograms of rubber per tree annum is to undertake the required number of tappings per tree per annum.

Relatively high rainfall and high number of wet days in the traditional rubber  growing areas in the country is a hindrance to achieve the required  number of tappings per tree per annum to obtain the potential yield.  Rain leads to no tapping days, late tapping days and also washouts all  leading to crop losses. Studies have revealed that around 30% of the  potential crop is lost due to interference of rain on harvesting.  The availability of an adequate number of skilled harvesters is  another factor needed to obtain the potential yield of a tree. However, rubber  growers very often complain of a lack of adequate number of skilled  harvesters. Studies conducted in this regard revealed that around 20% of  the potential crop is lost due to lack of adequate number of skilled  harvesters in the rubber industry.

Therefore, the total impact of rain and lack of adequate skilled harvesters on rubber tapping leads to about a 50% (30% + 20%) loss of potential crop in rubber  cultivations.

Accordingly, the land productivity level will further  fall from 1,492 to 746 (50% of 1,492) kilograms per hectare per annum.  According to the industry statistics the national yield level is 853  kilograms per hectare per annum (Table 2) and this could be possible as  there are some rubber cultivations with  good management and high level of technology adoption which can push the  overall national productivity to a higher level.

Countries such as India, Thailand, Vietnam  and Malaysia have demonstrated the possibility of achieving national  yield levels of around 1,500 kilograms per hectare per annum and also  sustaining it.

Economy of rubber growers

The national productivity of rubber lands in Sri Lanka is 853 kilograms per hectare per annum.  The current trading conditions in the country enable the rubber growers to sell their produce at the rate of around Rs. 250 per kilogram of dry rubber. The gross income from a hectare of rubber land per annum will be Rs. 213,250 (Rs. 250 x 853).

Though the land productivity levels and natural rubber  prices are at a relatively low level in the country, the worker wages,  cost of adopting agricultural practices like weeding, fertilising,  disease management and also the cost of other inputs are increasing each  year. In this background a gross income of Rs. 213,250 per annum from a  hectare of rubber land is inadequate to cover the costs whilst rubber growers obtaining a reasonable income for the investment they have made.

Due to such poor cash flow, the rubber growers lose interest in managing their rubber lands systematically. This scenario leads to the deterioration of the rubber cultivations further leading to a vicious cycle. It needs to be emphasized that rubber  growers should endeavor to improve cash flow through achieving high  land and worker productivity levels rather than depending on the price  to which the country does not have total control. 

Though the majority of the rubber  growers in the country are of the situation described above, there are  those who manage their plantations satisfactorily achieving land  productivity levels of the region of 1,500 kgs hectare per annum. Such  growers are able to get a gross income level of around Rs. 375,000  (1,500 x 250) per annum even under the current trading conditions.

This income level is comparable with that of well managed tea and coconut cultivations. With regard to rubber  and coconut at the end of the economic life span of the crop a good  income could be obtained by selling off the remaining trees. This income  could be in the region of Rs. 800,000 for both crops. Thus, if growers’  endeavour to adopt good agricultural practices they are still able to  achieve a reasonably high return on investment even under current  trading conditions and costs.

There are other plantation crops  with the potential of achieving much higher return on investments.  Cinnamon and palm oil for example are some of them and give a gross  income of over Rs. 1,000,000 per hectare per annum. Thus, for the  betterment of the national and plantation economy and for high income  levels of the growers and workers such crops too should be planted in  relatively large extents in the country.

With good agricultural and management practices, investments in rubber  cultivation too can yield a reasonable return on investmentThe  authorities need to give that confidence to the growers and also have in  place systems to provide them with technology, advisory services,  assistance in marketing, inputs such as quality planting material and  fertiliser together with strict monitoring systems in place.  Institutions responsible to provide these services need strengthening to  build the capacity to fulfil their mandate.

Increasing production Short-term strategies

There are a number of interventions to be done to the existing mature/revenue rubber  cultivations to enhance production in the short-term run. Due to the limited  inputs and low level of adoption of essential agricultural practices  partly driven by poor income levels, tree vigour and health in most of the  existing mature/revenue rubber cultivations are rather poor.

This situation could be corrected to a certain degree by adopting  good agricultural practices such as fertiliser application, soil and  moisture conservation and disease management uninterruptedly. Factors  such as poor quality of tapping and not undertaking tapping in all  possible tapping days too could be rectified in the short-term to  enhance national rubber production.

Though most growers complain about lack of skill harvesters  resulting in poor quality tapping and also inability to tap due to  interference of rain, technology available to mitigate such adverse  impacts are hardly adopted. Popularising low frequency tapping -  together with yield stimulation is the way forward to address crop  losses caused by the shortage of skilled harvesters. Interference of rain on rubber  tapping leads to significant crop losses and the correct adoption of  rain guarding technology would address this issue. The interventions  stated above, to deal with poor tree health, shortage of skilled  harvesters and interference of rain on tapping have a potential to  enhance the national rubber production by around 50% in the short run.

Long-term strategies

The relatively low number of rubber  trees per hectare and the poor vigour of the existing trees due to  non-adoption of recommended tapping policies together with poor systems  and quality of harvesting cannot be rectified in the existing  cultivation itself. However, these factors contribute significantly to  lower the national rubber production.

With this background and knowledge, rubber growers need to pay emphasis on achieving the recommended stand per hectare in all future newly planted and replanted rubber cultivations. Growers should endeavour to make each and every tree in their rubber cultivations vigorous plants.

Correct land selection, land preparation, soil and moisture  conservation, lining and holing, using of quality plants, adopting  correct planting technique, planting with the onset of monsoons, in  filling vacancies and replacing weak plants up to the second year from  planting, timely weeding, correct fertilizer application and timely  interventions to control pest and diseases are vital to achieve the  recommended number of vigorously growing plants per unit land area.

With focus on factors identified above it is possible for growers to bring a newly planted rubber  clearing into tapping in six years and also to have at least 480  vigourously growing plants per hectare at the time of commencement of  tapping. In such rubber clearings through  adoption of good harvesting practices/systems, use of skilled  harvesters and rain guards a cycle average land productivity level of  more than 1,600 kgs per hectare per annum could be easily achieved.

The  cycle average is lower than peak yields of around 2,500 kgs per hectare  per annum due to loss of total and healthy stand due to diseases, wind,  lightning and tapping panel dryness during the tapping cycle.  Increasing the total land area under rubber is another long-term approach to increase national rubber production. Recent studies undertaken by the Rubber Research Institute of Sri Lanka had revealed that rubber cultivation in the country could be extended to the intermediate zone of the country. One challenge the rubber grower has to face when planting rubber  in the intermediate zone is the impact of lesser annual rainfall and  the lesser number of rainy days per annum on the field establishment and  growth of plants especially in the initial two years.

This situation together with the uncertainty of the weather could lead to plant death and poor growth vigour. Though rubber could be set up even under these conditions’ investments on watering/irrigation during the first two years of a rubber  clearing would help to achieve a high stand per hectare consisting of  vigorous plants leading to high yield potentials during the maturity  period. The intermediate zone of the country has many positive features  for rubber cultivation. Abundance of  land, relatively flat terrain, fertile soil, less potential for  incidence of diseases, a greater number of tapping days per annum are a  few of them.


The Ministry of Plantation Industries is mandated to be responsible to the rubber industry of the country. The Rubber Research Institute, Rubber Development Department and the Thurusaviya Fund are the three institutions coming under the ministry to serve the rubber industry. The Rubber Research Institute of Sri Lanka is responsible for technology development and dissemination, Rubber Development Department for subsidy payments, monitoring of rubber smallholdings and providing advisory services to them while the Thurusaviya fund assists the rubber smallholders in their processing and marketing of their produce.

The country has a good institutional structure in place to work for  the betterment of the industry. Anyhow, adequate financial and trained  human resources and systems to retain the experienced and trained  employees are vital to obtain the mandated services from these  institutions.  Advisory boards consisting of members representing  different stakeholders of the industry would help to focus the  institutional work programs to cater to the current industry needs and  also to develop work plans to meet future challenges. 

Way forward 

Each year the country imports around 66,000 mt of natural rubber to bridge the gap in the raw material requirement of the natural rubber  value addition sector. For this the country spends around Rs. 16  billion in valuable foreign exchange each year. However, the  country has the institutional structure, human resources,  climatic conditions, land and investors to implement and operate the  short- and long-term strategies identified above in order to produce our  national requirement of natural rubber.

Becoming self-sufficient in our natural rubber requirement and making the raw material available to the local rubber  product manufacturer at a competitive price and at the correct time  while being a strength to them. To sustain the growth of the rubber industry it is vital that we protect the producer, i.e., the rubber grower. For this what is most important is the ability for rubber product manufacturers to buy the natural rubber  produced by our growers at a price so that they can earn a fair return  on their investment which could drive them to invest on good  agricultural practices. The country imports numerous value-added natural rubber-based  products. One such widely imported item is tyres. If the government  could provide a competitive advantage to the local manufactures for such  an item through appropriate tax structures, local manufacturers would  develop capacity to enhance farm gate prices of natural rubber.

Tea factory owners use a formula to determine the price for green  leaves based on the selling price of their products. A similar system  could be adopted in the rubber sector of the country as well though it may not be as easy for the tea sector. It is very vital that rubber producers and rubber  product manufacturers are benefited through more transparent and fair  trading systems to ensure the sustainability of the industry as a  whole. 

The writer is attached to the Wayamba University and is a former Director of the Rubber Research Institute of Sri Lanka.