Burying Burden in Knowledge.
One thing that comes as a problem with it, are insects who damage the crops. So Farmers are on a day to day look out for them throughout the planting season, killing as much as they can. It fairly deals with more than half of the damage.
The Wheat Grain was planted in mid mars and can be harvested in late August or Early September with a handsome yield. This method proved rather useful, because as mentioned before the Farmers brought a profit of 1 million Gold Coins after every harvest season.
That 1 million can this year be considered 800,000! Because they were planted when the Grand King managed to tame most of the 900 people population drop and the Castle explosion didn't even affect 1% of the crops. And considering that there are less farmers to kill insects now, it makes sense that the yield is a profit of 800,000!