The thermal diffusivity of soil at tropical stations in southern hemisphere

Summary The study of heat transfer or temperature changes in the surface layers of the soil are important in agricultural science at tropical latitudes. The quantity, thermal diffusivity largely determines the temperature changes produced in the layer of the soil when heat is conducted there from an adjacent layer. Therefore, the authors have determined the thermal diffusivity of the soil at the sites Arapongas (23.5°S, 51.7°W) and São José dos Campos (23.3°S, 45.8°W), in Brazil (South America), in accordance with the simple theory of periodic heat flow in a one dimensional, semiinfinite, homogeneous medium. The diffusivity increases with the increase of moisture content in the surface layers of the soil. The results of diffusivity obtained from these methods agree well with those of past workers obtained by other techniques.