Farming shouldn't be more profitable, period. As in any real life farm, large quantities of a product must be made to make any worthwhile profit.
The small profit during the sale of wheat, seed, pumpkin or melons is correct as it is. (If not slightly over-inflated)
The money to be made is not in the direct products of farming but processing these further.
Bread, cake, cooked pork or steak.
For an example, a lumber yard purchases it's raw material, lumber, at very low prices. It is not until this is processed into wooden planks, sleepers etc. that the profit margin is increased. Then again if a carpenter purchases this processed lumber and produces fine furniture that the profit margin is increased once again.