Introduction: Agriculture in modern times is getting more and more dependent upon the steady supply of artificial fertilizers and pesticides with the introduction of green revolution technologies. In the Andaman and Nicobar Islands about 1,50,000 hectares of forest was deforested to make way for agriculture and settlers. This resulted in the loss of top soil and reduction of soil fertility. Agriculture in the Andaman Islands is new as most of the pests and diseases are introduced. Due to change in the cultivation practice and also due to the limiting factors of Island ecology, many of the minor pests and diseases became major. A total of 15556.62 lakhs is the crop loss estimated by CARI in the year 2008.

 

Agriculture in the islands started with the establishment of penal colony in 1858. The modernization of agriculture was started by advocating the use of chemical fertilizer, pesticide and improved seeds which are imported from mainland and distributed to farmers at subsidized prizes. A track record of over 20 years of agriculture in the Islands shows that the land which supported the giant evergreen forest has not been able to support worthwhile agriculture.

 

The soil fertility map of Andaman Islands show medium availability of N and low availability of P and K. Hence it becomes necessary to enrich the soil quality using various artificial fertilizers. Further toxic chemicals like insecticides pesticides, fungicides, rodenticides are generally used to kill insects, weeds fungi and rodents respectively to protect crop plants or their harvested parts against their attacks. These chemicals are collectively called biocides. 

 

The Islands man made ecosystems comprise of agricultural crops and plantations, to grow more and more crops chemicals are being used indiscriminately. This may cause environmental disaster especially in coastal zones.

How they work: Fertilizers and pesticides may be introduced directly into the environment in a liquid phase, as a dispersion or solution or in a solid form as powder or granular form. Sprays are directed to the foliage. Solids are applied to soil surface or foliage. Some fertilizers are systemic that is they get absorbed in the Plant tissues and end up in the consumers. Some of them are contact, which are applied on the surface to fight pests and diseases.

 

These biocides tend to remain active long after destroying the target i.e. pests weeds, fungi and rodents. On continued application these agrochemicals causes contamination of food of food materials, disruption of natural balance of ecosystem by killing non target species and gradual increase in the immunity of target organisms to these chemicals. Further since most of these chemicals are not biodegradable they enter the food chain and persist in plant and animal bodies.

 

Bioaccumulation and bio magnification of pesticide: Continued use of huge amounts of different kinds of poisonous agricultural pesticides increase their concentration in the organism and multiplies through food chain and a phenomenon called biomagnifications is caused which moves up in the food chain and affects the apex species in the food pyramid. Man also situated at the higher tropic level of food accumulates these poisons and many cases of food poisoning and contamination are reported.

 

What compounds are used: The most common fertilizers used are DAP, MOP, Urea and Rock phosphate. These fertilizers provide Nitrogen, phosphorous and potassium which are very vital to plant growth. 

 

Nitrate: The dramatic response of this fertilizer has led many farmers to use it excessively which gets leached down to the ground water. In Neil Island ground water has been declared unfit for consumption because of leaching of fertilizers into the well. Nitrates cause eutrophication of water bodies. Nitrate causes health hazards like Methaemoglobnemia, cancer, and respiratory illness and toxicity to plants.

 

Fluoride pollution : Phosphates fertilizers and rock phosphate are very popular contain F as an impurity leading to high level of fluoride accumulation in soils and ground water leading to mottled teeth in children.

 

What pesticides are commonly used in the Andaman Islands: About 120 pesticides with 200 formulations have been approved for manufacturing and usage. Pesticide residues in food and milk are highest in India. 

 

Most pesticides such as DDT, DDE, DDD, dieldrin and heptachlor epoxide and most herbicides such as 2,3,5_T( 245 trichlorophenoxy acetic acid ) dioxin have been extensively used for control of diseases and crop destroying insects. Carbofuran, phorate, endosulphan, Quinolphos, Carbaryl, Dithane M,thiram, Strptocycline, bavistin, Streptoclcline, formalin, carbendazim,copper oxychloride, Dimecron Thiram etc are a few of the available pesticides in the Islands. Endosulphan series ,cyper methrine,DDT,BHC and weedicides such as glyphocite for eradicating grasses, termites for destroying ants,snails,and termites

 

In the Andaman Islands the agricultural department through their depot sell most of the pesticides and there are few private shops supply in pesticides. It was observed that 90% of pesticide sold was being for vegetable and rest 10% on other crops. The most wide spread contaminants because of agricultural are nitrates and phosphates inputs.

 

What is the withdrawal period: Most pesticides when used have a withdrawal period that is they should be applied in a stipulated time before their harvest. But this is not being followed by the farmers as vegetable production is mostly done by sharecroppers who want to reap maximum benefits in a limited time. The farmers are not aware about the dosages of fertilizers and pesticides and depend upon the sellers. Sometimes they are also misguided and end up using doses that are incorrect and unnecessary

 

Off late vegetables have become the focus of most farmers especially share croppers who get agricultural land on lease for farming activity. Vegetable production is very profitable and there is a tendency to use more than required dosage of artificial fertilizers. But the intensive use of fertilizers and pesticides is producing more vegetables but these vegetables come with a lot of side effects as the fertilizers and pesticides used are systemic and are retained in the tissues of the vegetables and can cause serious health Issues when consumed. The Shelf life of the vegetables produced presently is very small and also leading to economic losses.

 

Adverse effects are being noticed due to the excessive and imbalanced use of chemical fertilizers. This situation has lead to identifying of various diseases such as hypertension, kidney Failure, calcium deficiencies, stone formation in gall bladder and kidneys and bone disease. Use of Harmless bio-fertilizers such as vermin-compost in crop cultivation will help in safeguarding the soil health and also the quality of crop products. In a study conducted by Tamil Nadu agricultural university it was concluded that vermin-compost application reduces the inorganic fertilizer bill to the tune of 25 per cent.

 

The continued usage of chlorinated pesticides in agriculture has been responsible for the presence of residues in the grains, milk, eggs, vegetables and human tissues including breast milk.