here is a tip that might save you some time and money.
If you have windows that go down close to your garden beds be careful when applying fertiliser.
I have some Aluminium window frames that go right down to 1course above the floor.
Sitting above a garden bed. I notices white residue seeping from holes in the frame.
turns out I accidentally threw a little fertiliser up onto the window seal and the chemicals have reacted with the aluminium.
these are big window frames so putting in new ones is costly and messy work.
i contacted the manufacturer (Dowell) and the mentioned that I should wash out the area with bicarb soda, and cover the area with lanolin based tape. Couldn't find any lanolin based tape in Perth but got a jar of lanolin (sheep wool fat), smothered the area filling the corroded holes and then covering with a string waterproof tape. Seems to have lasted 18 months. so far.