[1] Szadzenie is caused by the hypercorrect avoidance of mazurzenie (mazuration) which is phonetically marked as rural and incorrect.
This phenomenon is common in areas which border mazurating dialects, for instance the Suwałki Region.
[2] Examples of attested words with szadzenie in Polish dialects noted in the Atlas of Polish Dialects (Atlas Gwar Polskich): proszo instead of proso ("millet, Panicum"), bydlęczy instead of bydlęcy ("bovine"), szmalec instead of smalec ("lard").
[3] The word szadzenie is derived from Polish word sadzić, colloquially meaning "to bother", pronounced in the relevant dialects as [ˈʂad͡ʑit͡ɕ] instead of [ˈsad͡ʑit͡ɕ].
You can help Wikipedia by expanding it.This article about Slavic languages is a stub.