Mr. Jayampathy Molligoda, (JM) Chairman, Sri Lanka Tea Board, in his article on a Sustainable solution to decline in tea production, export revenue and livelihood issues, in The Island of 17 May, concludes that there has been a gradual decline in tea productivity measured in terms of the yield per hectare in Sri Lankan tea estates, partly due to continuous application of chemical fertilizer.

It is correct that there is a gradual decline in the productivity of tea lands during the last few years. But, Mr. JM assumes that the decline in tea production is due to continuous application of chemical fertilizer. This assumption cannot be correct, as the Tea Research Institute (TRI) by the advisory circular SP 10 issued in August 2016, recommends application of mixed fertilizer containing nitrogen, phosphorus and potassium as urea, Eppawala Rock Phosphate and muriate of potash respectively, for mature tea fields in 2 to 5 splits per annum. This recommendation must be based on field trials conducted by research staff of the TRI. If the Chairman, Sri Lanka Tea Board assumes that continuous application of chemical fertilizer causes a decline in productivity, it is difficult to understand the above recommendation of the TRI.

Application of inorganic fertilizer is essential for growth of plants. This is adequately highlighted in the publication titled ” Effects of Fertilizers on Tea Yields and Quality: A Review with Special Reference to Africa and Sri Lanka by Okinda Owuorl, Principal Scientist, Tea Research Foundation of Kenya. Ref. https://repository.up.ac.za/bitstream/handle/2263/8222/Owuor_2001.pdf?sequence=1

The average tea yields of Sri Lanka are considerably lower than the potential yields. It has been reported that some of the cultivars developed by the TRI had been yielding around 8,000 kg/ha in South India under commercial conditions.. However, the average tea yield in Sri Lanka is much lower. Productivity of tea lands indicated by kg/ha/year has fluctuated around 1,600. In fact it has decreased from 1,736 kg/ha in 2014 to 1,602 kg/ha 2017, possibly due to undesirable weather, soil erosion leading to infertile soils, pests and diseases, etc. A study of the agricultural profile of the Corporate Tea sector was carried out a few years by the TRI. According to the findings of this study, the productivity of tea estates indicated by kg/ha/year, was less than 1500 in 183 estates. It is necessary that the RPCs implement an effective programme to increase the productivity of those estates giving low yields, after a detailed study to determine the reasons for the low yields so that appropriate action could be taken. Low per hectare yields could be due to a number of factors, such as soil degradation, old age of the crop, water shortage, etc

Soil degradation

Soil degradation in tea lands is mainly due to soil erosion, soil compaction, nutrition depletion, and loss of biodiversity, etc. According to a paper presented by Dr. M.A. Wijeratna of the TRI, at the first national symposium on Land Degradation held a few years ago, the loss of topsoil due to water erosion in the mid and up country tea lands could be in the range of 30-50cm, and this alone has been responsible for reduction of land productivity of tea by around 30-50%. If productivity of tea lands is to be sustained, it is essential that appropriate measures are taken to reduce soil degradation.

In view of the importance of soil degradation, the Ministry of Environment, in 2005, established an expert committee on Land Degradation. This committee comprised a number of experts in the field of land management, and its main role was to advise the Ministry of Environment, on issues related to controlling land degradation. This committee has not met since Feb. 2013. There are many ministries, departments and other institutions such as the TRI, which are expected to take appropriate measures to control land degradation. During the last few years a large number of seminars, workshops have been held on this topic. In spite of all these, land degradation continues to take place, evident by the common occurrence of landslides, depleted topsoil, siltation of tanks and reservoirs, decline in crop yields, etc. The Ministry of Environment (ME) needs to activate the already established Committee on Land Degradation, which would make appropriate recommendations to reduce land degradation to be implemented by the ME and other organizations. A land use policy has been formulated, but is not effectively implemented to reduce land degradation, which has serious repercussions on productivity. The land use policy needs to be implemented as an integrated programme in increasing the productivity of the tea sector.

Age of crops

A considerable part of the tea crop is old. For example, about 40% of the tea extent is under seedling tea and about 90% of the seedling teas are over 60 years old, and need replanting. Around 30% of the VP tea is more than 30 years old, and these also need replanting. According to the Ministry of Plantation Crops, during 2010-2012 the average annual replanting in the corporate tea sector was 1.1% , in the smallholder sector it was 0.7%. and the national average is 0.9%. Ideally this should be around 2%. If productivity of tea lands is to be sustained, it is essential that a replanting programme is implemented during the coming years.

Water Management

Rainfall variability is an inherent challenge for farming in tropical and sub-tropical agricultural systems. The variable rainfall also results in poor crop water availability, reducing yields to 25-50% of potential yields. Sri Lanka has been experiencing frequent droughts and floods over the last few years. Climate change prediction studies have indicated that Sri Lanka will experience high variability of rainfall. Some areas will get more rain during some months, and during the rest of the year the soil will be dry, affecting the crop. The simple solution in this case, is to increase the retention of water that is received during the rainy periods to be used during the dry periods. Around 40-60% of the amount of the rain that falls on land is lost due to run off, and only the balance of the total rainfall is infiltrated into the soil profile. Hence, harvesting the rainfall as much as possible would increase the availability of water in the soil, which will sustain the productivity of crops. The water retained by the soil profile is related to its depth, structure and also its organic matter (O.M) content. Hence strategies to increase soil depth and O.M levels would greatly enhance the water retention capacity, thereby increasing RW harvesting. If productivity of tea lands is to be sustained, it is essential that an effective water management programme is implemented in all the tea estates.

A Database on plantation sector

A complete and updated database on the corporate tea sector would be extremely useful in the endeavours to increase the productivity of this sector. Such a database will be of much use in planning, making policy decisions and management practices, such as replanting, diversification and identifying the development needs of the plantation sector; and would enable the relevant authorities to channel investments to sustain productivity of the sector.

The proposed database would mainly include data related to Land Use ( extent of uncultivated land, extent under forest and different crops, extent under nurseries) total annual production, YPH during the last five years, age categories of the crop, extent replanted during the last five years, source of water and degree of soil degradation etc. for each estate. I hope that the Chairman, Sri Lanka Tea Board will get the RPCs to develop an appropriate database, which will be extremely useful in sustaining tea yields.

Dr. C .S. WEERARATNA

csweera@sltnet.lk