DES MOINES, Iowa (AP) — The corn harvest continues significantly ahead of schedule in much of the grain belt with 15 percent of the crop out of the fields in the 18 states that produce most of the nation’s corn crop. That’s ahead of the 5 percent normal average for this time of the year. Iowa farmers are reporting 10 percent finished compared with the average of 1 percent. In Nebraska harvest is 12 percent complete compared with the 1 percent average. Missouri is more than half finished when the average is 15 percent. A few soybean farmers are harvesting with 4 percent done nationally. Two percent is the average. Crops were planted earlier this year because of a warm spring. Harvest is moving quickly because crops matured faster than usual in this summer’s heat.