In a new study published in the journal Nature Plants, researchers analyzed the supply chain of a regular loaf - from seed to sandwich and discovered that more than half its environmental impact comes from the production of the raw material, the wheat grain, instead of food processing. In fact, food actually causes about a third of total greenhouse gas emissions. The large environmental impact of food is largely affected by fertilizer; for example, ammonium nitrate fertilizer alone accounts for 43% of all the greenhouse gas emissions. Large amounts of energy and natural gas are needed to produce fertilizer and nitrous oxide is released when it is degraded in the soil. The problem can be ameliorated by reducing the amount of fertilizer used in agriculture. This can be accomplished by recycling agricultural and human waste as manure to retain the nitrogen. Also, organic farming and precision agriculture can be employed to lessen the problem.
I found the article to be very insightful. I never actually thought about the environmental cost of food production, so all of the facts were alarming. Food production is definitely a large contributor to greenhouse emissions, but the problem is difficult to solve. For instance, fertilizer aids farming greatly so reducing its usage will be a difficulty for farmers. Gradual improvements in farming such as employment of organic farming techniques may help reduce the problem, however.