What is the importance of the Yamamoto's farm in the novel, Echo?

Ivy and her family move to a farm owned by the Yamamoto family. The Yamamotos are being held because of their Japanese backgrounds after the Japanese bombed Americans at Pearl Harbor. The farm includes orange orchards and the Yamamoto's house, but also includes a small tract of land and another house. The Yamamotos give Ivy's family that house and land as a reward for taking care of the property while the family is away.