What are the motifs in On the Way Home: The Diary of a Trip from South Dakota to Mansfield, Missouri, in 1894 by Laura Ingalls Wilder?

Crops and farming are recurring ideas. The stated rationale of relocating from De Smet, South Dakota, to Mansfield, Missouri, is to seek a sustainable economic situation for the Wilder family through the process of farming. To this end, Wilder notes almost daily the type and condition of crops seen on the journey. She provides exacting details such as the height of crops, the types of soil and water available, the yield-per-acre of crops, the prices crops bring at market, and the cost of various types of farmland.