The food requirement of the world is increasing and livelihood of majority of the population is agriculture.
Hence the multiplication of harvests of crops is important for uplifting life status and income of a vast majority.
As a measure to declined agriculture due to Second World War introduction of new categories of crops and pesticides as well as chemical fertilizer took place.
Its objective was to gain more yield from a limited unit of land hence agrochemicals and non-renewable energy sources (eg. tractors) were used.
Simultaneously use of chemicals and machineries have spread to other fields and resulted in contamination of food with unhealthy materials, pollution of air and water, and disposal of radiation waste into biosphere. It was the period that rapid environmental pollution took place in the history.Considering on the negative effects of using agrochemicals a currently the attention is being paid in using integrated pest controlling methods. It can be observed that the old technology is used again.
The integrated pest management uses the scientific aspect of traditional 'Kem' (kind of ritual treatments).The integrated pest management means to control the pest population as to prevent them from harming the crops. This does not annihilate pests but control them in a certain level that prevents them from harming the crops. Our ancestors did the same thing with traditional Kem.Integrated pest management is one of five methods used in yield increasing of paddy cultivation.
It uses many old kem methods. A common feature in integrated pest management and old kem methods is not totally destroying the pests and strengthening their natural enemies. With the characteristics of the old society these kem were attributed a mystical form.Scientifically there is a suitable time to control any pest and old kem methods denote a certain time for it to be performed in order to match that time.
(eg. treatment for caterpillars with ash before the sunrise, controlling of flies in evenings).Old kem used kohomba, karada, ginger, davata, maduruthala, kapparawalliya, chilly and their volatility is important in pest control. In addition scientists who have identified the large range of pest controlling capability of kohomba have introduced it as a commercial pesticide to the market.Attracting birds in to the field is done in pest control and in the past it was done more systematically by planting mung and placing milk rice in lofts.The Kem method of a beehive is another successful method.
Today in Japan they widely use pheromones. Tying flies in a string, attaching in a lime with a pin are some old kem that used pheromones which shows the excellent pest controlling skills of our ancestors.
Another pest controlling method is the lamp traps. The insects that come to the lamp are destroyed. The old kem methods show that our ancestors knew these facts in the history. In addition mice, tortoises and snails can be controlled using food traps.Diya holmana, Diya yaka and diya takaya can be identified as pest controlling methods that used natural energy sources and they are categorised as mechanical methods in integrated pest management.
Generally we can observe that our old kem methods had a scientific base and there are many methods regionally. When ritual aspect adds to these methods they demonstrate a domestic identity.In historic Ceylon pest control was done with such kem methods and pests did not plague. It gave sustainability to the cultivation. We should use our traditional knowledge scientifically for a sustainable cultivation in Sri Lanka. That would result a more profitable agriculture in the country.
(An interview with the Hambantota District Director of Agriculture T. Hemantha Amarasinghe)
