David McGoldrick was close to giving Ipswich the lead against the run of play but his shot was well saved by Frankie Fielding.
Tommy Smith gifted Derby the opportunity to break the deadlock before half time when he brought down Richard Keogh in the area, but Loach reacted to save Ward's penalty with his feet.
Chris Martin thought that he had given Derby the lead early in the second half, but the on-loan Norwich striker's celebrations were cut short when the assistant referee raised his flag.
Both sides continued to push for a winner as the game reached its climax but Aaron Cresswell's drilled effort over the crossbar looked to be the final chance of the contest.
However, Edwards tried his luck with a speculative effort in the 93rd minute and he was rewarded as the ball beat Fielding before nestling in the bottom corner.