The Soil Association (UK)

on the impact of peak oil on food production.

Peak Oil and Nitrogen Fertiliser
'Peak Oil' will substantially affect agriculture, as many aspects of industrial production are energy intensive. In particular, Peak Oil will affect the viability of N fertiliser, because ‘natural gas’ is the basic chemical from which nitrogen fertiliser is produced, and there are no realistic alternatives. The use of fossil fuel energy for N fertiliser accounts for 37% of the total energy used by UK agriculture and its price tracks the price of natural gas. UK N fertiliser prices are rising significantly and are the highest they have ever been. Comparative analyses of organic farming show that it requires about half the amount of energy to produce the same quantity of food.

Implications of Peak Oil for the Soil Association
On the one hand, the increase and greater volatility of oil prices, and increasing physical shortage of oil could mean:

severe and prolonged global economic recession (ie. unemployment, low incomes/high cost of living, low expenditure, less business opportunities etc.). This could mean a fall in sales of more costly organic food.

severe impacts on Western lifestyles (high cost of transport, food and other goods). This could lead to increasing social unrest, such as fuel riots.

short-term and increasingly nationalistic Government policies. For example, more war in the form of foreign invasions to secure energy supplies.

significant pressure for Government investment in securing conventional and centralised energy sources, ie. nuclear and coal

in response to the harshening economic climate, more pressure to exploit natural areas and general downward pressure on environmental protection

change or even possible reversal of the comparative power and stability of countries, with those that are less 'developed' and thus less dependent on fossil fuels and trade, becoming more stable compared to the West

On the other hand, Peak Oil should mean an increasing move away from centralised and fossil fuel based systems, and a general move to self-sufficiency:

Emphasis mine. Click on the link to read the rest.

Soil Association