The trouble with these agricultural examples -- as a means
of trying to differentiate value theories -- is that the
conditions of production are not held constant (a similar
issue came up in relation to Torrens a few months back).
It's easy to see how, with favourable or unfavourable
weather conditions, a larger physical product might embody a
smaller amount of labour-time, or conversely.
Allin Cottrell
Department of Economics
Wake Forest University