Mulch.
The container needs 28 boards. you put in veggies. and every 24 hours whats ever in the inv(kinda like cupboard Inv) is turned into mulch(4 items to 1 mulch ratio) 1 mulch can be used in treeplanters pots to increase soil Q and you can put 1 mulch on veggie to get +5 seed.
some formulas:
Q of mulch container (carp + board Q / 5)
Q of mulch (all ingrediants qualities + container Q / 100)
Q of treeplanter's pot soil (soil Q + mulch Q / 2)
spreading mulch on veggie plant only get +5 if the mulch is +5 or greater Q than origional plant Q