Dr. Sarath Amarasiri Former Director General of Agriculture, Department of Agriculture Courtesy The Island

January 24, 2017, 7:49 pm

I recently read the document titled A Toxin Free Nation – A Three Year Plan, published in February 2016 by the Presidential Secretariat and the Ministry of Agriculture, which could be obtained from www.sema.gov.lk. One of the key items of the plan is to ban the importation of chemical fertilizers within three years.

Before I proceed to comment on the contents of this document, I need to introduce myself. I served the Department of Agriculture (DOA) for thirty six years, twenty four of which were as a full time researcher. Most of my research was on fertilizers, both chemical and organic. The time I spent on organic fertilizers exceeded that on chemical fertilizer. I have carried out detailed research on recycling rice straw, and use of animal manures and green manures as fertilizer materials. I headed a team that willingly soiled their hands collecting 770 samples of cattle, buffalo, goat, sheep, pig and poultry dung; and 670 samples of rice straw from different parts of the country, for a part of our research on organic fertilizers. Many papers have been published based on the findings from these studies. They are found in the DOA research journal “Tropical Agriculturist’ and elsewhere.

I am compelled to give my background to enable the reader to know that I am neither in the chemical lobby nor in the organic lobby, but just a scientist concerned with increasing agricultural productivity in Sri Lanka, enhancing farmer incomes, protecting the environment and minimizing public health hazards arising from improper use of fertilizers.

I wish to begin by making a few comments on some of the statements found in the document that I referred to above. Use of pesticides is not discussed here since I am not competent in that field (my comments are in italics).

Both Sri Lankan Experts and the World Health Organization (WHO) have found the cause of CKDu to be the mixing of brackish waters with sub-standard fertilizers and agro-chemicals.

The cause of CKDu in Sri Lanka has not yet been found by local experts or by the WHO or by any one else.

Water bodies from the smallest well and pond, to the largest reservoirs and rivers, have become vats of toxins unfit for human or animal consumption.

No vats of toxins have been reported from a single well, river or reservoir in the country as far as I know. This seems to be a gross exaggeration not expected from a document coming from the Presidential Secretariat. It is the responsibility of the appropriate state organization to inform the public about this statement. Is it correct or is it not?

Before the advent of the “so called Green Revolution” of the fifties, Sri Lanka exclusively engaged in toxin-free agriculture.

This statement is incorrect. The Tea industry began using chemical fertilizers in about 1905.

It is important that legumes such as urid, mung, gingelly, millet, chickpea, cowpea, etc are planted to replenish the nitrogen in the soil.

Gingelly and millet are not legumes. It is deeply regretted that such wrong information is given in a widely publicised document. School children may think this is true and give incorrect answers at important public examinations.

Destruction of farm lands has taken place due to application of agro-toxins. Soil nutrition is destroyed. Microorganisms and other fauna helpful to farming have been killed off.

Let the paddy yields from the most productive rice lands in the country do the talking. According to the official reports of the Department of Census and Statistics for the last ten years beginning 2005/2006 Maha season, the yields in Udawalawe ranged from 110 to 134 bushels per acre, while the average yield was 118 bushels per acre. Similar yields were reported for the Yala season. Furthermore, the yields from Mahaweli System H were also very high. These yields are as high as from anywhere else in the world, having similar soils, moisture regimes and number of sunshine hours in the cultivation period. One must take into consideration that the Mahaweli farmers had been adding chemical fertilizers for about 80 seasons, according to the DOA recommendations.It is very unlikely that soil nutrition has been adversely affected in these lands when the paddy yields have been so high for so long.

In December 2016, I visited Girandurukotte (Mahaweli System C), and drove past very large extents of rice fields that were being ploughed. These lands too would have received chemical fertilizers as for Udawalawe and System H. I saw thousands of White Egret (sudu koka) feeding on the worms and other organisms present in the freshly dug soil.

I have not read any published literature in Sri Lanka that addition of chemical fertilizers has destroyed soil nutrition and killed off microorganisms and other fauna helpful to farming.

Local scientists have taken steps to provide robust non-toxic fertilizer. Many of these products can be sold at competitive prices in the local market. The government will create the enabling environment for these manufacturers as part of this initiative.

It is correct that certain liquid fertilizers are sold in the local market. There is no evidence, however, that even a single properly designed field experiment has been conducted in Anuradhapura and Polonnaruwa districts, and in Udawalawe, by the Department of Agriculture or any other accepted research organization that proves their ability to provide the nutrients needed for rice cultivation.

Making Sri Lanka a Toxin Free nation

The Presidential Secretariat and the Ministry of Agriculture in their Three Year Plan highlight the following:

*All chemical fertilizers contain toxins

*Application of chemical fertilizers has led to a deterioration of soil health and eradication of soil organisms.

*Organic fertilizers such as cow dung and microbial fertilizers do not contain toxins

*Organic fertilizers and microbial fertilizers will produce wholesome food that will lead to a healthy nation =Chemical fertilizers will not be imported, after three years

The following are my observations:

I do not agree that organic fertilizers are toxin-free. Consider cadmium which is a well known carcinogen (cancer causing) and a nephrotoxic (kidney damaging) element. The World Health Organization and the Ministry of Health have declared that cadmium is a risk factor for CKDu (Note: Not a causal factor).

It is present in triple super phosphate (TSP) and in all phosphate fertilizers in the world, including Eppawela rock phosphate. The government regulations prohibit the importation of phosphate fertilizers having more than 3 mg/kg cadmium.

It is found in any soil on earth. Any plant, including grass, contains cadmium. Grass is known for its special ability to absorb cadmium from the soil. Therefore, it can be said that there is no cow dung in the world that does not contain cadmium.

The published scientific literature gives the following values for the cadmium content of cow dung in England and Wales, Switzerland, China and Sri Lanka as 2.50, 2.00, 0.80 and 0.43 mg/kg respectively, on a dry weight basis. Incidentally, the cadmium content of poultry dung and pig dung is much higher than that of cow dung.

Consider a lorry load containing 5000 kg of fresh cow dung that is added to one acre of land in a year. At 80% moisture its dry weight is 1000 kg. The cadmium added to the land in a year would be 430 mg.

Consider the DOA maximum recommendation of TSP to rice, which stands today at 22 kg for an acre per season. The addition of cadmium to one acre of rice fields for two seasons would be 132 mg, assuming that TSP contains the allowed maximum of 3 mg/kg cadmium

Therefore, using the above calculation, it can be concluded that cadmium addition from cow dung exceeds that from TSP. Let us be mindful, however, of the assumptions made in the above arithmetic. It assumes that TSP in Sri Lanka does not have more than 3 mg/kg cadmium. It further assumes that the farmer adds only 1000 kg of dry cow dung (amount present in 5000 kg of fresh dung) containing 0.43 mg/kg cadmium.

As such I do not wish to imply that this analysis has universal validity. What I wish to strongly emphasise here is that cow dung is not toxin-free. I must admit that when we started our research on cow dung forty years ago, we had not even heard of cadmium as a potential toxin. Nor did DOA possess instrumentation to determine cadmium content at that time.

What happens when chemical fertilizer importation will be banned in three years?

*No urea and TSP will be imported after December 31, 2018.

*Rice yields in the country will suffer a drastic decline because organic fertilizers will not be available locally, having the ability to supply the same amount of nitrogen as that supplied at present from imported urea. None of the microbial fertilizers in the market have proven their ability to supply the nitrogen requirements of the rice crop. Nitrogen is the most yield determining factor for rice grown anywhere in the world.

*Banning TSP importation will not lead to an immediate drop in rice yields, since there is a soil build up of phosphorus from past applications of TSP in some rice fields. However, yields will definitely decline with time because Sri Lankan soils are not rich in plant available phosphorus as proven by field experimentation. Eppawela rock phosphate cannot be used for rice cultivation, and the much touted microbial fertilizers are yet to prove their effectiveness to make soils under flooded conditions release the insoluble phosphate compounds that are naturally found in the soil.

*Organically grown food does not guarantee that it is toxin-free, unless plants are grown in liquid medium without soil.

*No country can be toxin-free. Sri Lanka should strive to keep toxins at manageable levels.

Dr. Sarath Amarasiri

Former Director General of Agriculture, Department of Agriculture