Here are five areas to watch when Northwestern’s spring football practice begins on Saturday:

1. Quarterback competition: Junior-to-be Kain Colter, sophomore Trevor Siemian and redshirt freshman Zack Oliver will all get a shot at the starting job with the graduation of Dan Persa.

Colter is the leading candidate after filling in for Persa when he was injured last season. Colter was 55-of-82 passing for 673 yards, six touchdowns and one interception. Siemian also saw time and was 16 of 26 for 256 yards, three touchdowns and one interception. Northwestern could use multiple quarterbacks with Colter being a threat at wide receiver. He caught 43 passes for 466 yards and three touchdowns last season.

“As I told him a year ago at this point, ‘You’re going to be on the field,’” Northwestern coach Pat Fitzgerald said recently of Colter. “‘I don’t anticipate you standing next to me a whole lot.’ I fully anticipate that this year, and I fully expect it to be at quarterback. But I think Trevor has something to say about that. I think Zach has something to say about that. That’s what’s so fun about spring ball is the competition. We’ll see where we’re at after 15 practices.”

Fitzgerald said he’d prefer to have a starter anointed by the end of the spring practices, but he was also fine with continuing the competition in the early fall practices.

2. New targets: The Wildcats graduate their top two wide receivers in Jeremy Ebert and Drake Dunsmore. The pair combined for 120 receptions, 1,522 yards and 17 touchdowns last season. The Wildcats do have experience back at the position, but a few players will need to step up their production. Senior-to-be Demetrius Fields had 32 catches for 382 yards and three touchdowns last season. Junior Rashad Lawrence caught 19 passes for 203 yards and one touchdown. Sophomore Christian Jones had 16 catches for 195 yards. Sophomore Tony Jones will also return to the group after redshirting last season due to a knee injury. He caught 11 passes for 157 yards as a true freshman. Of course, Kyle Prater will also join the team in late March after transferring from USC Trojans, but he probably won’t be eligible until the 2013 season.

“It’s not who fills into Jeremy’s role,” Fitzgerald said. “It’s, ‘What do you bring and how we’re going to build your role based on your skill set.’ We have good depth there.”

3. Improving at running back: Northwestern’s running game did actually take a step forward last season. The Wildcats went from rushing 155.9 yards in 2010 to 166.6 yards in 2011. The yards also came more from their running backs than their quarterbacks. Jacob Schmidt (471 yards), Treyvon Green (362 yards), Adonis Smith (266 yards) and Mike Trumpy (182 yards in three games) had success at times. Yet, Northwestern still hasn’t had a dominant back since Tyrell Sutton rushed for 890 yards in 2008. Trumpy will sit out spring ball after suffering a knee injury last season, and Smith recently decided to transfer. Green will be the main back to watch during the spring, and it should be a competition between him, Trumpy and incoming freshman Malin Jones in the fall. Venric Mark could also be in the mix.

“It’ll be a great competition to who’s going to get the lion share of the reps,” Fitzgerald said. “We’re looking for consistency. That’s what we’ve been lacking. Why did we go 6-7? We as a program were not consistent. Was running back one of those positions? At times, yes. Was it improved from a year ago? I believe so. I really do.”

4. Defensive tackle replacements: Northwestern lost both starting defensive tackles, Jack DiNardo and Niko Mafuli, to graduation. Senior-to-be Brian Arnfelt, junior Will Hampton and sophomore Chance Carter should be among the main competition for the job.

“Don’t sleep on Brian Arnfelt,” Fitzgerald said. “That would be the one guy as I’ve watched this winter [who] has really, really progressed. He’s always been a hard worker. That hasn’t been the issue. Just breaking through some self-limitations. He’s at a place that I’m really, really proud of him.”

5. Secondary overhaul: Sophomore safety Ibraheim Campbell is the one certainty in Northwestern’s secondary. Everything else is up for grabs, and the secondary was a problem at times last year.

“We got a lot of open spots,” Fitzgerald said. “People have to go out there and earn roles. That’s what I’m looking for -- individual improvement. And I’m looking for guys to solidify some roles pretty quickly from the standpoint, ‘I can go out there, and we can win with me in this role or that role.’”