(1) For the purposes of this Subdivision, if:
(a) an entity carries on a primary production enterprise; and
(b) the value of all the trading stock on hand at the end of a tax year is greater than the value of all the trading stock on hand at the beginning of that tax year;
the entity's income for that tax year in the form of profits from the enterprise is to include the amount of the difference in values.
(2) For the purposes of this Subdivision, if:
(a) an entity carries on a primary production enterprise; and
(b) the value of all the trading stock on hand at the end of a tax year is less than the value of all the trading stock on hand at the beginning of that tax year;
the entity's income for that tax year in the form of profits from the enterprise is to be reduced by the amount of the difference in values.