MOISTURE AND HEAT FLUX THROUGH SOIL PROFILE T. H. S Barros 1 , D. P. V. Leal 2 , F. D Bender 3 , L. C Santos 4 , A. J Farias 5 , R. D. Coelho 6 ABSTRACT: Temperature and soil heat flow importance to plants, is based on theirinfluenceon water and nutrient uptake, seed germination, root development. On the other hand, soil moisture is one of the most important variables in the soil-plant-atmosphere exchange process, as well as for infiltration, drainage, hydraulic conductivity and irrigation studies. It was aim to study the heat flowin the soil profile at different depths in response to soil moisture. The experiment was conducted in an experimental area of the Department of Biosystems Engineering (LEB) of the Luiz de Queiroz School of Agriculture (ESALQ/USP) located in Piracicaba, SP. Thermocouples were installed in the soil profile at depths of 5, 20 and 35 cm. The treatments consisted of soil conditions without and with irrigation in the field capacity. The results were analyzed with the F test at 5% significance. From the results obtained, it is concluded that, the variations in the heat flow generally decrease with soil depth increases, and the effect of the moisture on the heat flow in the soil is accentuated in the condition of greater humidity for 5 cm depth. KEYWORDS: Soil temperature, moisture, irrigation, soil heat flux. UMIDADE E FLUXO DE CALOR ATRAVÉS DO PERFIL DO SOLO RESUMO: À importância da temperatura e do fluxo de calor no solo para as plantas, ocorre desde a sua influência na absorção de água e nutrientes, germinação de sementes, desenvolvimento radicular, entre outros. Por outro lado, a umidade no solo constitui-se numa das variáveis mais importantes nos processos de troca entre o solo e a atmosfera. Neste sentido, objetivou-se estudar o fluxo de calor no perfil do solo em diferentes profundidades em resposta a umidade. O experimento foi conduzido em área experimental do Departamento de Engenharia de Biossistemas da Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ/USP) em Piracicaba, SP. Foram instalados termopares no perfil do solo, nas profundidades de 5, 20 e 35 1 PhD. Candidate at ESALQ/USP, Piracicaba – SP, Brazil. E-mail: timoteo@usp.br 2 Professor at FAZU, Uberaba -MG, Brazil. E-mail: daniel.pvelosoleal@yahoo.com.br 3 PhD. Candidate at ESALQ/USP, Piracicaba – SP, Brazil. E-mail: fabianidenise@usp.br 4 Professor at UEG, Anápolis – GO, E-mail: lucas.cs21@gmail.com 5 PhD. Candidate at ESALQ/USP, Piracicaba – SP, Brazil. E-mail: jesusf@usp.br 6 Professor at ESALQ/USP, Piracicaba – SP, Brazil. E-mail: rdcoelho@usp.br