Nitrate, Explosives, Fertilizer

This is a suggestion that would knock out several birds with one, maybe two stones.

1. Add a new "Compost Pile" building. Simple to make, but has to be unlocked. It produces Nitrate by consuming Berries over a long production time, 3 days or so like Bot production. (just flavorfully letting them decompose and such)

2. Nitrate is added as a required ingredient for Explosives, as currently only taking Paper is flavorfully a bit off.

3. Either add a new Flag type building or a new job to the Forester building to apply Fertilizer to Tree Saplings to give them a growth bonus similar to Beehives. Note this would be re-applied each time the tree is harvested.

4. Add a new recipe to the Explosives Factory that produces Fertilizer from Dirt+Nitrate. This adds a consumption for Dirt outside of only terraforming.

So this accomplishes several things:
1. Adds a use for Dirt in the late game.
2. Adds a way to improve efficiency of logs.
3. Makes Dynamite production more accurate.