A manufactured home was damaged Tuesday evening after a sealed bucket of fertilizer on the front porch ignited by spontaneous combustion at about 5:45 p.m.. Moisture inside the container combined with the fertilizer to create heat, Riddle Fire Chief Jim Powell said. Because there were no holes in the bucket to release the heat, it built up until bursting into flame, he said. The fire burned the porch and a roof above it at the home in a mobile home park in the 300 block of East Fifth Avenue, Powell said. Homeowner Penny Wells used a hose to extinguish much …