Harvesting Aquatic weed for biofertiliser – another dead rope for the farmer?

By Chandre Dharmawardana, Canada

Mr. I. C. P. Mendis, writing to The Island (“The organic deal – killing two birds with one stone”, 15-05-21) proposes to harvest aquatic weeds like Water Hyacinth (“Japan Jabara”) to make organic biofertiliser and clearing the water ways, too. This suggestion is preceded by a conspiratorial theory mentioning Dr. Senaka Bibile, an old colleague of mine, who pushed for generic pharmaceuticals. Then Mr. Mendis meanders into claiming that those who support the use of agrochemicals are treacherous agents of multinational companies who are only interested in profits.

Mr. Mendis says, “The defeated forces have now received some oxygen, and we see even the high and mighty, who were sent reeling home at the polls, attempting to make their presence felt. There is everything which points to financing by the fertiliser lobby, against the organic fertiliser issue”.

Mr. Mendis forgets that those who were defeated at the polls also championed organic fertiliser, under the slogan of a “Toxin-free Nation” and even banned glyphosate. This government has exempted many such pesticides and key agrochemicals from the “ban” which seems to be mostly in name.

After hatching the conspiracy claim, Mr. Mendis suggests making organic fertiliser, and possibly bio-energy out of the aquatic weeds dragged off the water and processed. Farmers, or commercial outfits are called upon to do this. He has himself NOT tested it, as is typical of most suggestions for “going organic”.

In my view, adopting a full organic programme worldwide is environmentally bad for the world (and impossible for Lanka) because it needs twice as much land, and twice as much water to put into practice. Then there is the danger of plants accumulating metal toxins (phyto-accumulation) and those getting into manure when plant matter is recycled by composting. Adrian Meuller, a leading world authority advocating organic farming wrote a lead article on organic farming in the journal NATURE and showed that if the world were to “go.organic”, the world population must be halved, and they should become vegetarians to free up cattle ranching land for growing food. A link to Mueller’s work may be found in my comment on Mueller’s research given in the link:.

https://dh-web.org/place.names/posts/CD-Mueller-OrganicL.pdf

The right solution is a hybrid approach. BUT SRI LANKA’S PROBLEM IS NOT ORGANIC VERSUS MINERAL FERTILISER. IRRESPECTIVE OF WHAT FERTILISERS WERE USED, THE FARMER CANNOT GET HIS PRODUCT TO THE MARKET. An indebted farmer cannot implement cutting edge ecologically sound farming practice. All the price guarantees, and purchase schemes of successive governments have been a farce. So what is the use of talking about fertilisers, pesticides, good agricultural practices, etc., if in the end the farmer cannot market his prodcut, and he/she is forced to even commit suicide? In contrast, the plantation sector has a good marketing system since colonial times. There is no excuse as to why good agricultural practices, soil remediation, etc., have not been adopted by, say, tea estates.

Unfortunately, instead of tacking the real issues of the small farmer, all kinds of irrelevant solutions are proposed. Let us look closely at Mr. Mendis’s proposal because such suggestions were tossed out even in the 1970s when I worked as a Professor of Chemistry at what is today the SJP university. The basic numbers to evaluate the feasibility of such projects have been avialble for a long time.

Eichhornia crassipes (Water Hiacynth) and various types of aquatic Ipomea, Hydrilla, Ceratophyllum are found on water bodies that receive the nutrient-rich run off from agricultural land and grabage dumps. Typically 20% or more of the water surface may get covered, and Ceratopphyllum and Hyrdilla may develop submerged thick mats that asphyxiate the aquatic system. However, harvesting the voluminous material from the water poses grave problems:

(a) collecting them into drying beds or composting areas equires heavy dredging equipment that burn expensive fossil fuel.

(b) The harvest, when dried, is negligible. Thus, 1000 square meters of aquatic area usually provides about 800-900 kg of dry material, although the harvested wet weight is 9-10 tonnes. The ten tonnes of wet smelly material cannot be easily dried in the sun and need special kilns,. It cannot be directly composed without mixing with suitable dry material. In effect, it is very inconvenient and expensive to work with.

(c) The composted material, even under the best conditions contains only 2-2.5 % nitrogen. That is, ten tonnes of initial material produces merely 15-20 kg of nitrogen fertiliser after much investment in energy, and machinery!

What Mr. Mendis in his goodness of heart has done is to give a “dead rope” to the farmer. At the end of the day the farmer is left bankrupt while the elites who clamour for organic food on their plate will look after themselves somehow.

The impact on the aquatic system of the lake is also not unfavourable. The sudden removal of the top layers of the aquatic weeds lets sunlight into the submerged weeds which now grow profusely. It is well known that aquatic weeds cannot be controlled in this naive manner of simple harvesting of the surface growth. It is mechanically quite demanding and expensive to remove all the submerged growth as well.

In fact, when a lake is clogged, many complex methods of reclaiming are needed. This includes the introduction of fish species (“grass carps”) that eat up the submerged growth, and then harvesting the surface growth gradually. In addition, control of soil erosion and run off from the neighbouring urban and agricultural lands need to be undertaken.

The best solution to prevent aquatic weed growth it to put floating solar panels on the water. Then no aquatic growth occurs submerged or on the water surface. Water is conserved by the reduction of evaporation day and night, and electric power is produced during the day time.

Mr. Mendis has been carried away by a seemingly simple but mostly impractical idea. Similar proposals to convert plastic into petrol, purify water with “kumbuk” roots, provide potassium to soils with left over banana skins, tackling Covid with coriander, ginger and herbal smokes (“dhum hattiya”), or asking the farmer to make his own fertiliser with a few buckets of cow-dung and a few bales of straw in his own “kumbura” are very fashionable these days. An individual introduced as a Professor of Agricultural, speaking on a TV programme claimed that imported oranges, i.e., “rata dodan” do not contain Vitamin C. Only the local “paeni dodan” was claimed to have Vitamin C.

I have written many articles pointing out that the claim that “Sri Lanka’s rivers and soils are contaminated with poisons” is an utter falsehood. Chemical analysis of the river waters and soil have shown no significant amounts of heavy metals or pesticdes.

If “people eat posisoned food”, as claimed by the ochestrations for organic food, the life expectance should drop drastically due to chronic toxicity. Countries like Singapore and New Zealand, etc., use some 100 times more argochemicals per hectare compared to Sri Lanka, and the life expectancy in those countries have INCREASED since the days prior to modern agriculture. The incidence of cancer, kidney disease, etc., has NOT increased in Si Lanka with time. Instead, the disease has decreased and the life expectancy has increased. The kidney disease endemic in the Rajarata is a result of hurriedly settling farmers in the accelerated Mahaweli C programme in areas where the water in their dug wells is found to be contaminated with fluoride and magnesium ions of geological origin.

In a very recent U-tube emission Dr. Padeniya of the GMOA claims that since 1960, Sri Lankans have been EATING POISON IN THEIR FOOD. Mr. Mendis also seems to think so, and want people to eat only organic food. But the attached graph shows that the life expectancy in Sri Lanka has steadily increased, except during the Eelam wars.

So Mr. Mendis, and Dr. Padeniya, what kind of poison in the food increases the life expectancy of Lankans? What kind of posion decreases infant mortality?