'baled' is the regular past/past-participle form formed in Modern English by adding -ed to the verb 'bale'. The verb 'bale' (meaning to make into a bale) comes from Middle English 'bale' / 'balle', from Old French 'balle' (12th century), ultimately from Late Latin 'balla' meaning 'a package, bundle'.

'bale' entered Middle English as 'bale'/'balle' (from Old French 'balle') and later developed as a verb (to form into bales); the modern English verb 'bale' produced the past form 'baled' by regular inflection.

Originally the root word referred to 'a bundle or package'; over time it gained the verbal sense 'to make into a bundle (bale)', and 'baled' now denotes something that has been made into a bale.