Central Ideas of Buckingham (1907): A Century Later

687 Edgar Buckingham became involved with soil physics for 5 yr at the turn of the twentieth century. His general goal was to advance understanding of moisture movement and evaporation from soils to improve irrigation and crop management. Specifi cally, he was interested in elucidating why evaporation from near the soil surface in arid areas during summer months was self-limiting (Buckingham, 1907; Narasimhan, 2005). Based on carefully conducted evaporation experiments from soil columns, and infl uenced by Fourier’s heat equation, Buckingham formulated a conceptual model for soil-moisture movement and presented his ideas a century ago in his celebrated work Studies on the Movement of Soil Moisture (Buckingham, 1907). The history, content, and relevance of this contribution has been addressed by many (e.g., Nimmo and Landa, 2005; Narasimhan, 2005). On the centenary of Buckingham’s seminal contribution, the purpose of this paper is to reexamine the central ideas of Buckingham’s paper and refl ect on how his conceptual model for moisture movement in soils has withstood time.