 |
| Agriculture |
|
| Agriculture is a very important human activity in any country. Agriculture is a primary activity - serving as the basis of many other activities. Agriculture supports food production, textile industries, food - based industries, agro - processing industries, oil - industry, sugar industry, etc. |
| |
| There is a misconception that agriculture does not cause pollution and is harmless. But, agriculture is the source of large pollutants let into our environment. The main reason to consider as an activity generating pollutant is the use of synthetic chemicals in agriculture. |
| |
| With the advancement of agricultural science to meet the challenges of increasing production on a limited area - large number of synthetic chemicals are commonly used. Important chemicals used in agriculture include: |
| |
| a) Fertilizers |
| |
| b) Pesticides |
| |
| c) Growth promoters and retarders |
| |
|
| Fertilizers are a class of synthetic chemicals supplied to crops in order to increase their growth and yield. |
| |
| Important fertilizers used in agriculture include urea, dia-ammonium phoshate, muraite of potash (potassium chloride), potassium sulphate, gypsum (calcium sulphate), urea - ammonium phosphate, super phosphate, etc. |
| |
| The fertilizers leave large amount of residues in the soil - which are either retained in soil to create imbalance in ecosystem or flown with water to cause water pollution. Sometimes, excess application of fertilizer can result into gaseous release of pollutants like NH3 (Ammonia) by volatalisation. |
| |
|
| Pesticides are a class of synthetic chemicals used to control the pests of crops. Pests can be an insect, disease or weed or sometimes non - insect pest like rats. |
| |
| Various chemicals used to control the pests can cause large scale pollution - as less than 5% of applied pesticide reaches the actual pests and balance 95% enters the eco-system. The pesticides may remain in plant bodies and may accumulate in edible part of crops or pesticides may persist in soils to cause serious damage to biological balance in the soil. Pesticides can also enter ground water and may act as source of water pollution. |
| |
| Some important pesticides commonly used in agriculture are: |
| |
| Organo-chlorine chemicals |
| |
| They are highly dangerous pesticides having the ability to persist in plant bodies and soil for long period to cause innumerable ecological and health hazards later. |
| |
| Examples: DDT, BHC, endosulfan, heptachlor and chlordane. |
| |
| Organo - phosphorous chemicals |
| |
| They are also dangerous pesticides with ability to kill many useful bacteria besides killing the pests. They act as a source of pollution of agricultural land and ground water. |
| |
| Examples: Phorate, methyl parathion. |
| |
| Carbonates |
| |
| They are used as insecticides, acaricides or nematicides to kill insects, mites and nematodes respectively. They can kill many aerobic and anaerobic bacteria in soil. They are easily escaped in underground water- when excess dosage is used. |
| |
| Examples: Carbofuran, aldicarb and carboryl. |
| |
| Ethylene Di Bromide (EDB) |
| |
| They are volatile liquids used to produce gaseous poisons to kill stored grain pests. They can leave traces of dangerous chemicals on grains and cause food pollution. |
| |
| Triazines |
| |
| Many triazines like Atrazine, Simazine are commonly weedicides to kill weeds in agriculture. They have potentiality to remain in soil and to be flown into ground water to cause drinking water pollution. |
| |
| Phenoxy alkonates |
| |
| They are the weedicides causing serious damages to the ecosystem, as they can kill variety of plants apart from weeds. They can also remain in soil and can cause water pollution - when they fail to degrade in soil medium. |
| |
| Examples: 2,4 - D, 2,4,5 - T |
| |
|
| Many growth regulators like gibberellic acid, naphthalene acetic acid, maleic hydrazide etc are used in agriculture to suppress or enhance the growth of crops or to initiate flowering or to increase the fruit size. They are likely to cause pollution in edible part of the crop - as they can remain in fruits, grains when extensively used. |
| |
