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Published online by Cambridge University Press: 28 April 2015
The most important issue raised in the comment by Bradford involves the problem of how to handle the fact that, although the logical period for accounting for energy use on the farm is one year, farm machinery is typically used over a period of several years. No solution to this problem will be entirely satisfactory, and the alternative offered by Bradford has its own difficulties. Nevertheless, the Bradford alternative is worth trying, and this response to the comment will consider briefly his proposal.