Mostly Gas!

Agriculture as it is mostly practised today is a significant contributor to greenhouse gas emissions. It contributes 14% and is fourth after electricity and heat generation (22%), land use change and forestry (18%)and transport (18%). The main sources are methane from livestock, nitrous oxide from agricultural soils, and carbon dioxide - primarily from energy and fuel use. Importantly, these emissions often also represent the loss of valuable resources from farming systems - and therefore opportunities for enhancing productivity and livelihood opportunities. The main sources of agricultural green house gases arising from modern agriculutre are as follows -
1. Carbon dioxide emissions from the heavy use of gasoline-powered agricultural machinery that modern techniques require.
2. Carbon dioxide emissions from the deforestation and burning of land to convert it for intensive agriculture.
3. Loss of soil and forests as carbon sinks. Natural vegetation acts as a huge reservoir, soaking up atmospheric carbon, as does the soil. Destruction of the plants and the disruption of the soil that occurs when land is converted to agriculture decrease the availability of these sinks, meaning more carbon is left in the atmosphere. Modern farming techniques also increase soil erosion and the leaching of soil nutrients, which decrease the use of soil as a sink. Rough estimates are that man-made changes in land-use have produced a cumulative global loss of carbon from the land of about 200 thousand million tonnes.
4. The use of synthetic fertilizer releases huge amounts of Nitrous Oxide(N2O) – it is the single largest source of N2O emissions in the world. The application of fertilizers accounts for 36% of the total emissions of N2O. According to the IPCC, if fertilizer applications are doubled, N2O emissions will double, all other factors being equal. Since regular applications of fertilizer are an integral part of modern farming, and as the developing countries adopt more of these industrialized agricultural practices, this is a dangerous situation. Remembering that N2O has over 300 times the warming potential of CO2 and can stay in the atmosphere for about 120 years, the effect on global warming could be devastating.
5. Methane (CH4) released from animals and manure piles. Manure storage and treatment systems equal 9% of total CH4 emissions and 31% CH4 emissions from the agricultural sector. Most of the CH4 emissions come from the liquid-based manure management systems that are commonly found in modern livestock farms with large populations of animals.
Apart from this the indirect contributions of modern farming are even greater. The manufacture of synthetic fertilizer is one of the most intensive energy processes in the chemical industry, which itself is a primary energy user globally. Add into this the need for the fertilizer to be transported to the farmer, and we find that synthetic fertilizer is the largest producer of CO2 emissions in the agricultural industry – even considering all the tractors and equipment belching out exhaust fumes. The use of synthetic fertilizer tends to acidify the soil, which then requires the application of lime to balance the pH; manufacture of lime also produces CO2 emissions. Finally, synthetic fertilizers suppress the soil’s natural micro-organisms that break down methane in the atmosphere, which leads to higher levels of methane than otherwise. The soil micro-organisms are largely responsible for controlling soil temperature and water run-off, production of vitamins, minerals and a host of plant hormones, not to mention that soil micro-organisms provide much of a plant’s immune system so reducing their population is harmful. Thus modern agriculture is unsustainable from the point of view of its harmful contribution to global warming.
Simultaneously economically too this modern agriculture is proving to be unsustainable. The main problem with modern artificial input agriculture is that there is a natural limit to the artificial inputs that the soil can take and so the amount of fertilisers, pesticides and water to be applied goes on increasing while the yields go on falling and sometimes the crop fails altogether. Consequently the economic costs of providing the inputs go on increasing while the realisation of the value of agricultural products in the market does not keep pace with this rise in input costs. Inevitably, in the case of India, this leads to farmers falling into the clutches of moneylenders and becoming enmeshed in spiralling debt. Matters have been compounded by the reduction in the availability of cheap institutionalised credit and various kinds of government subsidies for fertilisers, water, diesel and electricity in recent years. The economic crisis in agriculture has now assumed serious proportions with thousands upon thousands of farmers having committed suicides, sold their lands, houses and even their kidneys.
Another problem arising from the adoption of modern agriculture has been that of the increasing scarcity of water. Most of the water needed for irrigation in India is being provided by groundwater extraction and this has led to a situation of "water mining" wherein water collected in the deep confined aquifers over hundreds of thousands of years have been used up in the space of a decade and large parts of the country are facing a ground water drought from the late nineteen nineties onwards. Presently there is less and less ground water available for not only irrigation but also for drinking and the cost of its extraction is continually going up.
Finally modern agriculture drastically reduces the agricultural bio-diversity with its stress on mono-cultures. For example in the western Madhya Pradesh region there has been a reduction in the acreage under coarser cereals and pulses which have been replaced by soybean. This combined with the greater monetisation of the rural economy has forced the marginal adivasi farmers to buy their food from the market instead of getting it cheaply from their farms and this has reduced their nutritional levels well below healthy standards. Thus they too have become sufferers of the problem of chronic hunger that today engulfs the poor in much of the developing world and even in the developed countries because the shrinking of livelihood opportunities has meant that they are not able to earn enough to buy wholesome and adequate food. Thus, it would not be wrong to say that modern agriculture mostly produces gas these days!