Umpire duties in field

Question
I coach a 18 and under fastpitch team using ASA rules. At our last game, the opposing team had a runner on first with one out. The batter hit a routine grounder to the pitcher and was called out at first by the umpire positioned by second. The opposing team coach appealed the play to the home plate umpire. She said the field umpire shouldn't have made the call, she should. She called the runner safe and was put back on first. This can't be right, is it?  

Answer
Thanks for the question!

You are correct, this is completely wrong.  The base umpire has all calls at first base unless the base umpire goes out to see an attempted catch.  Even when they are behind short stop, they have first base.  The plate umpire has third base once in a while when a situation occurs that is between this phrase, "The base umpire has the first out in the infield at any base and the last runner all the way to third."

The first part also assumes that the "first out in the infield" is a ground ball, not a ball hit in the outfield.  All other situations, the plate umpire covers third base.

I hope this answers your question, if not please reply!