Dan Zumbach lost 50 acres of corn when the Cedar River flooded. Yet he considers himself lucky. Most of his 160 acres would have been lost if not for family, friends and neighbors who gathered Saturday with combines, grain carts and semitrailer trucks to harvest a field near Palo. They worked from noon until 11 p.m. before the rising waters forced them to quit. Iowa's widespread thunderstorms and torrential rains have done more than flood Iowa's cities and towns. They have also slowed much of the state's corn and soybean harvest. Officials are trying to assess how many acres have been impacted by flooding, but it's likely to be thousands, they say.