Adelaide forwards Jason Porplyzia and Lewis Johnston have signed fresh contracts with the AFL club.

Both have signed one-year contracts to remain with the Crows.

Porplyzia, 28, endured a poor season and was dropped from Adelaide's side late in the season, while the 22-year-old Johnston suffered a knee injury which limited his output to the last five games.

"Jason would be the first to admit he was below his best this season but we believe he's an important player," Adelaide's list manager David Noble said in a statement on Thursday.

"Lewis showed some very promising signs when he got his opportunity late in the season ... we think he has the potential to become a key component of our developing forward line."