Requirements:

Tend a Carbon Covered Sheep, Sooty Swine and Ashen Alpaca
Harvest 50 Compost Piles

Rewards:
Volcano, 3 Fertile Ash Boost, Spicy Deer Jerky
Notes: Sheep, Swine and Alpaca come from the Ashed Animal in the Market. Compost Piles are a free gift. Ash Spreaders are crafted.
Each Spreader requires 3 Fine Drills (Pine Trees) and 6 Dented Wheelbarrows (Wall Post)