The Fertilizer is added by the MineFactory Reloaded mod. Like most MFR Machines , it runs on either BuildCraft or Industrial Craft 2 power. The Fertilizer provides nutrients to any plants that are growing in a 3x3 area in front of it. (unless you add a Range upgrade (MFR) to it)
It uses Industrial Fertilizer, Forestry Fertilizer or IC2 Fertilizer.
Like the Planter, Harvester, the Fertilizer affects all vanilla plants that can be affected by bone meal (wheat, melons, pumpkins, carrots, potatoes, trees of all kinds, and cocoa), as well as flax.
This kind of fertilizer can be obtained by pumping Sewage (MFR) into a Composter (MFR)