In

a year with exceptionally good weather conditions, the production function

curve will be higher and parallel to the curve above.

If

there is an upper-limit on the amount of grain that can be produced, then the

curve will end up horizontal for large number of farmers.

A discovery of new high yielding crop seeds would tilt the production function

curve higher anti-clockwise, pivoted at the origin.

In

a year of bad drought the production curve can turn downwards for large numbers

of farmers.