142 DRY-FARMING 
5 2s ae 
Fic. 33. Many soils check badly. The cracks cause a loss of soil mois- 
ture. Arid soils (this picture represents a heavy clay as depicted by 
Lyon and Fippin) often crack extensively. Cultivation will prevent 
the loss of soil-moisture. 
almost wholly at the surfacé. Yet it is well known 
that evaporation from the soil surface may continue 
until the soil-moisture to a depth of eight or ten 
