The developments that followed industrialization have made our life very comfortable. We are able to enjoy many facilities and privileges. Our works have become easier. But in the process of bringing out such developments, we have unknowingly caused great harm to our environment. As a consequences different environmental problems have arised. One such problem is that of the global warming.
Global warming is the gradual increase in the temperature of the earth’s atmosphere. It is caused by the presence of green house gases in the atmosphere. These gases trap and reradiate the solar radiation thereby increasing the atmospheric temperature. Some of the important green house gases that contribute to the global warming are carbon-dioxide (CO2), methane (CH4), water vapour, nitrous oxide (N2O), ozone(O3)etc. Though industries and combustion of fossil fuels are a major source of these green house gases, agricultural industries also contribute significant amount of these green house gases particularly carbon dioxide, nitrous oxide and methane. Agriculture sector as a major source of green house gases should be a cause of great concern for everybody as intensive agriculture are practiced to meet the demand of the ever increasing population.
How agriculture contribute to green house gases: Agriculture is practised in different ways in different regions. If we study the way it is practised in India, many of the processes involved in leads to global warming. Mention may be made of the following:
Deforestation: In certain parts of India such as in parts of north eastern regions, Orissa, Madhya Pradesh etc people still practice the shifting cultivation. It is a type of agricultural practice in which crops are cultivated in a new agricultural lands every year. The lands used for cultivation would be left fallow after the crops are harvested. Often large areas of forest are cleared off by burning to prepare new agricultural lands. Such large scale deforestation contributes to global warming in two ways:
- Release of carbon-dioxide by burning
- Forests are an important source of carbon sink as they utilize the carbon dioxide present in the atmosphere during photosynthesis, thereby keeping in check the amount of carbon-dioxide present in the environment. When forests are destroyed, the carbon-dioxide molecules are not removed from the atmosphere.
Preparation of the land: Apart from the forest, soils are also another important sink of carbon. Carbon is stored in the soils in the form of un-decayed plants and animals remains, and other organic wastes. When lands are ploughed or tilled, carbons from under the soil are released which react with the atmospheric oxygen to form carbon-dioxide.
Excessive applications of fertilizers: chemicals are added to the soils to increase the nutient content and improve crop productivities. However in India, most of the farmers do not have the adequate knowledge of how much of the fertilizers to add to get the maximum yield. Often the only knowledge they have is that fertilizers would increase crop yield.So, they often apply more amount than is actually needed. Most of the fertilizers not used by the plants are changed into nitrous oxide by the soil microbes and released into the atmosphere. The molecules of nitrous oxide are 300 times more potentially harmful than the carbon-dioxide molecules.
Cultivation of paddy plants: cultivation of paddy plants needs the fields to be flooded with water. Such flooded fields create oxygen deficit environment. Degradation of the organic matters present in such soils releases methane.
Use of livestock: Livestock like cattle, goats, buffaloes are an important part of Indian agriculture. The bulls are used for ploughing fiels and for transportations of goods. As wheat stalks act as a good fodder, farmers often practice animal husbandry along with the agricultural farming. These animals produce methane during the digestion of food. These gases are released in the atmosphere when they exhale it.
Apart from these processes, agriculture can also indirectly release the green house gases during the transportation of goods, use of farm machineries like tractors etc.