U.K. fossil fuel reserves could last for 150 years at present rates of consumption. But energy prices must be expected to rise in real terms and this will affect crop production costs. An amount of energy equivalent to 4-3% of national consumption is used by agriculture and an overall total of 19% by the food system as a whole. The largest user of energy in agriculture is fertilisers (23%), followed by petroleum (18%), imported feedstuffs (13%), off-farm feedstuff processing (13%), machinery (10%) and electricity (9%). Energy has been substituted for manpower through the increased use of machines (and thereby relieved much drudgery) and energy for land through increased fertilisation of crops.
Energy itself may become limiting one day, through reduced availability and / or increased cost. It is shown that energy conservation measures can be practised or have potential in relation to the use of petroleum fuels, the more efficient use of machines, minimisation of cultivations, crop drying, glasshouse heating, heat recovery in milk cooling and minimisation of fertiliser requirements. Some alternative energy sources are also considered and these include solar heating in crop drying and for water, reject heat utilisation, geothermal energy, windpower, animal wastes, plant residues and energy crops. Responses will occur only as fuel prices rise in real terms so that alternative measures show economic benefits.