Measurements of cumulative evaporation from bare soil

Careful measurements were made of evaporation of soil water during 1921 in California at Davis, Delhi, Mountain View, and Whittier. The soil surface was kept free of vegetation and no rain fell for periods of eight to 12 weeks. Analyses of the records indicate that an average curve of evaporation loss against time may be useful for situations where more exact data are not available. Other studies of soil in tanks reveal that, after the first week, the evaporation rate from bare soil without a water table is extremely slow. For a period of 1547 days during which rain was excluded, the average evaporation rate was 0.00236 inch/day. When water tables were maintained at depths between 0.5 and 5.0 ft it was found that the evaporation loss from uncropped soils with high water table was not directly proportional to the depth from the soil surface to the water table.