it could either be a given tool or something buyable for pc or spc. what it would eventually do is convert dead/wilted any destroyed plants into fertilizer. I don't think a 1-1 ratio would be good Mabey a 10-1 or something or it could count the grade of the destroyed plants until it gets to a certain value.
if you wanna be extra you could even set what type of fertilizer you'd like to get. (ie use and plant type)

Converting extra seeds into fertilizers would be a neat idea. With regulars plants able to be harvested indefinitely as long as you keep the the plant watered you wind up building up a large surplus of seeds that are going to sit around and do nothing. Would be nice to throw a stacks of unwanted seeds into a compost bin to get fertilizers.

There could also be different value amount based on the usefulness of fertilizers like pumpkin based fertilizers cost more items to make compared to the normal plant fertilizers.

Yeah like a add seeds and dead plants to our compost bins the get random fertilizers but then there are also recipes to get certain fertilizers!