WATCHUNG, N.J. — Led by a 1-under-par 70 from senior Nathan Han , Columbia completed Round 2 of the Ivy League Men’s Golf Championship on Saturday. The championship is being held at Watchung Valley Golf Club. Han climbed five spots on the individual leaderboard into a two-way tie for seventh at even-par 142 after two rounds. His Saturday included an opening birdie at the par-4, 434-yard first. Another birdie at the par-4 eighth helped Han make the turn at 1-under. He parred six consecutive holes before posting another birdie at the short par-4 15th. The senior from Somers, New York…