These recipes produce more of an item than they use, so feeding part of the output back in grows your supply.
Minecraftcontentexpansion · Greenhouse · From MinecraftContentExpansion
Its other inputs are renewable, so this loop gives an unlimited supply of Sugar Cane.
Vanillaautomated · Farmer recipe · From Vanilla Automated
Its other inputs are renewable, so this loop gives an unlimited supply of Sugar Cane.
Farmingutils · Internal farmer · From FarmingUtils
Its other inputs are renewable, so this loop gives an unlimited supply of Kelp.
Mechanical_botany · Insolating · From Create: Mechanical Botany
+ minecraft:water
Its other inputs are renewable, so this loop gives an unlimited supply of Kelp.
Vanillaautomated · Farmer recipe · From Vanilla Automated
Its other inputs are renewable, so this loop gives an unlimited supply of Kelp.
Voluminousenergy · Hydroponic incubating · From Voluminous Energy
Its other inputs are renewable, so this loop gives an unlimited supply of Kelp.