by Devaka Dias

1. Vegetatively Propagated Teas are CLONAL HYBRIDS which requires high and correct nitrogen ratios to reach its potential yield of over 3,000 kg per hectare made tea per annum.

2. The required norm is 10 kg nitrogen for every 100 kg of made tea. If soil carbon ratios are good at 7% organic matter in the soil, improving the cation exchange (ability of soils to hold nutrients) capacity, it is possible to reduce the N ratio from 10 N to seven N per 100 kg made tea. However, timing and the method of application is very important to derive absolute benefit.

3. Most soil where tea is grown in Sri Lanka is eroded and the organic matter in the soil is so poor that the tea is fertilizer dependent.

4. A field yielding 3,000 kg of made tea per hectare will require 300 kg N. Less if the soil carbon is good. The N per one ton of compost is believed to be low at 1.5% nitrogen. Based on this, one hectare of tea yielding 3,000 kg per hectare will require 20,000 kg of compost each year. Cost of procurement and application will be prohibitive and not cost effective and practical.

5. The quality of compost supplied to the industry requires to be closely monitored, particularly if imported, as there is the risk of introducing nematodes and other pest and diseases that we did not have hitherto.

6. Where compost is produced locally, proper C:N ratios must be ensured to give a standard of 20:1 or below. Quality control is a must or there will be repercussions as with high ratios the bacteria in the compost will draw nitrogen from the soil.

7. Compost fertilizer will be unable to match nitrogen, phosphate & potassium ratios recommended by the TRI. For example if the potassium levels are too high, it will bring about a magnesium deficiency making the leaf yellow.

8. If nitrogen is reduced, production will take a huge dip and leaf supplied to the factory will not be healthy for producing good tea. Succulent leaf is required for good tea manufacture but with less nitrogen the leaf will be yellowish and leathery. This will result in a brownish tea and high percentage of off grades. Poor quality tea will not fetch good prices at the auctions and the overall average will dip with both the factory and the green leaf supplier severely affected. The tea factories will run into problems of not being able to achieve the desired out-turn from green leaf to made tea which should be 21.50%. Even a loss of 0.50% will mean a loss to the factory in monetary terms which they can ill afford. A tea factory manufacturing 500,000 kg of green leaf based on a green leaf rate of Rs.100/= per kilo, incurring a loss of 0.05% on the out-turn will incur a loss of Rs.250,000/=.

9. The reduction of nitrogen over a long period of time will weaken the tea bush and the casualty rate will be very high after pruning.

10. Dependence on artificial fertilizer can be reduced but not completely stopped. Reducing the current rate of application cannot be done overnight and must be implemented in stages at the grower level. I suggest the following steps:

a. Encourage the grower to establish Gliricidia and Albizzia shade and maintain it correctly. A good cover of both type of shade ensures improving the soil carbon over a period of time. Fifty kg of gliricidia leaves adds 01 kg nitrogen into soil. In land with a high gradient, de-silting of drains is a must.

b. In land with a poor cover of tea due to erosion, most of the soil carbon will be lost and the grower must be encouraged to infill. Bright sunlight falling directly on the soil burns up soil organic matter very fast and also leads to the loss of ammonia in the soil when the soil temperature increases. Therefore establishing shade and infilling vacant tea patches is essential.

c. By changing the method of fertilizing, efficiency can be improved. Currently, the method of fertilizer application is to apply the manure on the surface of the soil by what is popularly known as broadcasting. This, I consider, to be the most inefficient method of application leading to loss of ammonia. I have over a decade adopted a different method of placement of fertilizer.

While this is expensive, it successfully reduces the volume of fertilizer that need be applied. The fertilizer is placed in a 6-inch deep alavangoe hole, one and a half feet away from the bush on the upper side of the slope and the hole covered. The cost of placement works out to three and a half workers per acre as opposed to one when broadcasting. It is a crime at today’s cost to waste fertilizer by broadcasting using more volume than necessary to compensate for volatization. More so as there is a big government fertilizer subsidy.

R & D is required to invent an applicator for fertilizer placement.

In conclusion I must say that with good agricultural practices, dependence on artificial fertilizer can be reduced but we cannot go 100% organic. It is important to educate tea growers, 70% of whom are smallholders using very much more than recommended doses of fertilizer, to mend their ways. They believe that applying more fertilizer means overnight crop increases and make five or six applications when four would suffice if correctly timed. What the smallholder does not understand is that we have to only replace N that has been removed from the soil. This is why we go on a replacement ratio of 10 kg N to 100 kg of made tea which could be reduced to 7% if the soil organic matter is good.

If a study is done on the fertilizer use by the smallholder and N replacement ratio worked out, I am sure the figure will be astronomical. This is where lot of money is wasted and must be corrected. With proper use of fertilizer, imports can be reduced and valuable foreign exchange saved by the country.

The authorities must also develop a method of issuing fertilizer to smallholders based on their production. This should not be a problem as the factories have the required information. In my opinion four application of fertilizer is more than enough with application during and after the two monsoons when the assimilation is best.

Reducing rate of N application with artificial fertilizer, in my view, does not require addition of compost if proper agricultural practices are followed. In an estate I work on, the soil is very rich in organic matter on account of a good cover of Albizzia and Gliricidia. No soil is exposed to direct sunlight as a lot of Albizzzia leaf litter and twigs and gliricidia loppings lie on the soil. They slowly disintegrate into colloids that will attract a negative iron to bind the ammonia and other elements such as Pottasium, Calcium etc.

I appeal to the authorities to rethink the ban on inorganic fertilizer imports. Immediate change will cause a lot of hardships to the grower, particularly the smallholder who contributes 70% to the national production and depend on this income for a living. The grower requires to be educated on the importance of soil organic matter to get them to adopt correct agricultural practices and reduce dependence on artificial fertilizer.

Halting inorganic fertilizer and moving totally to organic will cause irreversible damage to the industry in many ways. What is required is to improve the soil organic matter and reduce the dependence on fertilizer. One has to keep in mind that the tea industry is an interconnected web and the ban will not only affect the grower and the factories but also many others indirectly employed in the tea industry.

(The writer is a senior planter from a planting family with 48 years experience in the industry.)