Reaching for the sun
While man-made pollution continues to starve plants of vital light and energy, scientists are rediscovering the age-old wisdom of natural farming

By Dr. Ray Wijewardene

How very right the ancient Egyptians were in their worship of the sun-god Ra as the giver of all life. How very right the Zoroastrians are in their worship of the sun and fire as fundamental to existence.
Those of us with the privilege of a pirivena grounding to our education will recall being taught the four “elements” of life in Ahpo, Thayjo, Vahyo, Patavi. The Pali word “patavi” represents the solid or earth state; “thayjo” represents the state of “heat”, or “energy”, or “fire”; ahpo represents the liquid state or water, while vahyo represents air or the gaseous state. We learnt how these four elements worked with the help of an illustration, using ice, water and vapour as an example: a piece of ice is the solid state (“patavi”) which, when heat (“thayjo”) is applied, turns into the liquid state (“ahpo”), and with the application of still more heat turns into vapour or the gaseous state (“vahyo”). All these states or elements are reversible when heat is reduced or eliminated: vapour reverts to liquid, and in turn liquid turns to the solid state of ice as heat (or energy) diminishes. Central to all of these elements is heat, or energy, or fire, (“thayjo”) – the sun itself.

View down a 'gaman-alliya', while adjacent are the 'saru-alliyas', with the coconut palms claiming the topmost canopy. The shorter Gliricidia forms the next canopy providing both fertility (NPK) and fuel-wood. Titonia - high in potassium and nitrogen - occupies the third canopy, and the nitrogenous ground-cover carpets the soil and nutrition-recycling organisms therein.

It is only comparatively recently, in the last few decades, that we have come to appreciate the more fundamental differences between tropical agriculture, which depends on year-round sunshine, and temperate agriculture, which depends on seasonal or summer sunshine, which may last for only a few months each year.

The practice of growing rice – a temperate crop – came to us from southern China, through India. As a seasonal, four-month crop, rice has adapted well to conditions in Sri Lanka, with its water-saturated valleys (or “yaya”) between the rain-fed uplands of the tropical “haena” (chena). The adaptation is mainly in the use of water in the control of weeds (hence the traditional 20 tonnes of water to grow just one kilogram of rice!).


Again, it is only recently that the importance of sunshine has been fully appreciated in the growing of rice, especially in the approximately 20-day period prior to harvest, when the vital starches move, through photosynthesis, from the leaves and into the grain.

An essential sunshine-intensity requirement would be (in scientific terms) at least 500-600 calories/ (15-17 megajoules/sq.m./day) during this “grain-filling” period (eg. January and February) to ensure a yield of at least six to seven tonnes of rice per hectare. Failure to achieve this level of sunshine invariably results in reduced yields of four to five tonnes per hectare.

The ancient rice farmers’ wisdom in choosing the North-Western Province and the North-Central Province, and also the Eastern Province, is reflected in the way they ensured rice cultivation even in times of drought or low rainfall by drawing on the ingenious system of tanks, where water would be stored during the months of excess rainfall.


Coconut is the country’s primary crop in the intermediate zone (the agro-climatic-region between the wet and the dry zones). The coconut palm has adapted well to the North-Western Province, with its two periods of rainfall – April-May-June and September-October-November – in a year of sunshine, as required by a perennial crop that needs intensities of over 16 MJ./sq.m/day. The sunshine is essential for the photosynthesis that moves the starches in the leaves and into the nuts being formed at their axils (where they join the palm).

It will be observed that rice, the temperate crop, is in particular need of sunshine during the weeks prior to harvest, while coconut, the perennial crop, needs sunshine throughout the year. A period of weak sunlight (as filtered through “haze”) invariably results in a drop in yield the following year. This was observed in 2006 and 2007, and is predicted for the year ahead because of the heavy cover of haze (which prevents sunlight from reaching the leaves) experienced in the first half of this year.


Earlier efforts to co-relate coconut yield fluctuations with rainfall over the preceding year have been only partially correct, as periods of rainfall are usually associated with “hazy” cloud-cover.

In the mid-to-late ’70s, however, excessive haze cover (or sunlight-diminishing haze) occurred without corresponding rains. The resulting reduction in coconut crops these past years can be only partially attributed to climate change. In fact, the climate change we are experiencing could be more the result of changes caused by our own pollution of the atmosphere. Micro-particulates released into the air by the partial combustion of petroleum fuels form nuclei around which the moisture in our normally humid atmosphere coalesces. This results in an umbrella-like cover of haze which acts as a barrier to the passage of the sun’s rays to the foliage beneath.

Extracted from Grain Harvesters (1975) :W.Buchele illustrates an early harvesting machine as described from Pliny's time. The cart with crop-steadying comb in front is pushed into the standing crop while the farmer beats the grain directly off the standing crop and into the cart.

In the 1930s and ’40s, Britain’s capital London experienced such a haze, when atmospheric pollution reached exceptionally high levels. The “pea-soup” fog was a result of particulates released by partially burned coal fires from thousands of domestic fire-places throughout the city. The mist and fog spread through much of the surrounding counties. The situation started to improve with the introduction of gas-fired-heating.

Similar “fogs” are experienced in Los Angeles, California, in the United States, where the automobile population is dense and generates a high volume of pollution. These fogs, which can rise to altitudes of a few thousand feet; are trapped in the valley landscape of this part of California; in addition, low wind speeds prevail. Stringent laws have been introduced to restrict emissions from internal combustion-engined vehicles and to encourage the move towards the electric motor, a trend that is being followed in other states.

Pilots flying over Colombo have observed similar atmospheric conditions prevailing over the city. Unfortunately, this haze – a barrier to sunshine – has been spreading to other parts of the country, where population numbers are growing and motorised traffic is on the rise. Pollution levels will rise further with the setting up of coal-fired generating stations around the country.


Certain plants, known as C-4, contain an inherent characteristic that boosts the efficiency of the photosynthesis process. This plant category, which includes maize (corn), sorghum, sugar-cane and bamboo, can photosynthetically convert a greater quantity of carbon dioxide (CO2) in the atmosphere into biomass. Unfortunately for us, rice, wheat, coconut and other common crops grown in this country do not possess this facility; these crops are referred to as “C-3”, as they convert only a lesser quantity of available CO2 into carbon.


Through genetic modification, scientists can manipulate certain crop seeds to ensure they do not grow according to the pattern of the first generation (F-1). These “terminator seeds” prevent the farmer from using a portion of his harvest as seed for the next crop. He then becomes dependent on the seed merchant for his supply of seed requirements for the next crop.

Rice seed is undergoing genetic modifications that will give it C-4 characteristics. The scientific process is being closely guarded by internationally recognised research institutes, which are ensuring that the process does not fall into the hands of exploitative multinationals. It is now widely known that rice can be manipulated to a C-4 configuration.

Any research efforts to “breed” such characteristics into the coconut should be carefully monitored. However, the process could take decades, considering the more difficult conditions relating to the breeding of perennial crops. Meanwhile, recent changes in traditional practices in the growing of coconut suggest fresh directions by which the tree’s photosynthetic capabilities may be enhanced.


The importance of photosynthesis in agriculture has been recently reappraised in its role in the cultivation of commercial (or food) crops and as an agent for promoting the wellbeing of soil organisms (earthworms, etc.) that feed on decaying vegetation.

These organisms convert and recycle (through their digestive systems) the minerals present in the quartzes and sands of the soil, and into “plant-available-form” as nutrition for crops cultivated on and above the soil. This is the basis of natural farming, as practised worldwide. The practice is also termed “organic farming” or “green manuring”: micro-fauna consume the micro-flora in the soil and recycle this nutritional content to feed crops under cultivation.

The processes of “composting” support and maintain the warmth required by these organisms. The art of composting has evolved to help accelerate the activity of these micro-organisms by giving them more favourable conditions in which to breathe, live and multiply.

In Sri Lanka, the traditional Kandyan forest garden has for generations deployed the wisdom and science behind the green manuring concept: forest vegetation flourishing under year-round tropical sunshine is used for food, fertiliser, fuel and forage; meanwhile, vegetative nutrition falling from the forest canopies enriches the soil below.

Green manuring serves in the cultivation of the various spice plants grown commercially in the region, and also fruit trees like jak and breadfruit, and a variety of the legumes that form an important part of the local diet. These supplement the rice grown in the “vela” or levelled-paddies of the valleys below these “haenas” (or undulating-rain-fed-uplands).

Sadly, this was not understood by the tea planters of old who were more used to the open-field system of farming practised in the western and temperate regions they hailed from. They dismissed haena (or chena) cultivation as wasteful, failing to appreciate the subtle rotational and multi-function system in this form of farming.

A revised system (now known as “alley-cropping” and “SALT”, for sloping agricultural land technology) is gaining fresh appreciation for its unique adaptability, especially in the world’s humid-tropical regions in Asia, Africa and central America.

Once condemned as a destructive “slash-and-burn” system, “haen govithan” or chena cultivation is now considered a preferable option for the land than the practice of cutting, burning and then digging up the naked, erosion-prone soils for mono-crops, such as coffee and tea.

If you happen to visit a forest region in search of a particular villager, you may hear the following: “Neh mahatthaya, kelay eliya karande gihillah”, which can be translated as: “He is away giving light to the land.”

Previously, we might have translated this thus: “He has gone to clear the forest”, implying “slash and burn”. The farmer’s real intent is only to prune the upper growth so as to let sunlight fall on the crops he has sown in the fertile and weed-free soils.The cultivation of the rubber plant (Hevea) comes closest to the natural forest, and does not involve the pernicious and erosion-prone practice of “clean weeding” as practised on farms in the temperate western regions.“Chemical farming” bypasses these natural processes. Chemicals are applied directly to the crop being cultured. But this practice invariably results in the destruction of a vast proportion of the soil-organisms, and pollutes sub-soil water resources leading to surrounding tanks, irrigation schemes and domestic wells.


A systematic reversion to natural farming is being researched in a modern approach to the growing of coconut, thus returning to the wisdom behind both the Kandyan forest garden and the more sustainable features of the haena system. This is achieved through the “companion” or complementary growing of fertility-restoring crops.

In the coconut approach, the alleys or avenues between adjacent lines of coconut palm alternate between the “gaman elliya” (covering plucking, collecting and transport) and the “saru elliya” (contributing towards the fertility needs of the system).

Husks, if not dry-decorticated, are buried between the palms to perform the dual function of conserving (sponging) valuable moisture and recycling the palm’s valuable needs of potassium and magnesium contained in the coir pith.


The harvesting of cultured crops takes place in the periods of brightest sunshine. The long summer-holidays enjoyed in the west were timed so that the children returning home from school could help their parents harvest the crops.

Around the world, the harvesting of crops has proven the most labour-intensive of all farming operations. The plucking of tea, the tapping of rubber, the picking of coconuts, the harvesting of rice (cutting, gathering, conveying, threshing, winnowing, drying and bagging) – all take place in the brief periods of sunshine between monsoon rains.


It is little known that the tea bush (a temperate crop adopted from China and Japan) is, in the tropics, grown throughout the year, with year-round (muted) sunshine). The tea bush is selectively-harvested about once every five days. The tea bush in Japan, however, is mainly dormant during the winter months, and grows mainly in the sunnier spring and summer months; it is harvested only two or three times a year. The bush, however, is cleverly “pruned” at the start of spring, so that a “two-leaves-and-a-bud” yield is achieved across the table for harvesting in one sweep (manually or mechanically). This precludes the need for the far more labour-intensive operation of “selective-plucking”, and cuts down harvesting costs.

The lesson for us here is that “mechanisation” does not simply mean the “mechanic-ing” of a manual operation.

In 1964, this writer was presenting “The Landmaster Saga” to an agri-business class at Harvard Business School. The lecture was enthusiastically received. Buckminster Fuller, the world famous engineering designer, happened to be a visiting lecturer and our course director. He rose and asked me: “Did your tractor mechanise tropical agriculture, or did it just mechanise the buffalo?”

I was “floored”. The class eagerly awaited my response. I could give none that was appropriate. The next morning the subject was taken up again with the question: “What was the farmer really trying to achieve when ploughing his field?” And he quoted from Robert Browning: “A man’s reach must exceed his grasp, or what’s a heaven for?”

And thus began a new phase in my life: Reaching for the Sun.

(The writer is former Chancellor of the University of Moratuwa and ex- Principal Scientist of the International Institute of Tropical Agriculture)

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