_____________________________________________________________________________________________________ *Corresponding author: E-mail: yblawal@futa.edu.ng, lawalyusuf.b@gmail.com; Physical Science International Journal 26(3): 45-54, 2022; Article no.PSIJ.88314 ISSN: 2348-0130 Effect of Near-Earth Surface Temperature on Soil Temperature at 5 cm Depth O. C. Adebayo a , Y. B. Lawal b* , O. R. Obasi-Oma c and J. S. Ojo d a Department of Physical Science, Yaba College of Technology, Yaba, Lagos State, Nigeria. b Department of Physics, University of Africa, Toru-Orua, Bayelsa State, Nigeria. c Department of Physics, Lagos State University, Lagos State, Nigeria. d Department of Physics, Federal University of Technology, Akure, Ondo State, Nigeria. Authors’ contributions This work was carried out in collaboration among all authors. All authors read and approved the final manuscript. Article Information DOI: 10.9734/PSIJ/2022/v26i330316 Open Peer Review History: This journal follows the Advanced Open Peer Review policy. Identity of the Reviewers, Editor(s) and additional Reviewers, peer review comments, different versions of the manuscript, comments of the editors, etc are available here: https://www.sdiarticle5.com/review-history/88314 Received 18 May 2022 Accepted 22 July 2022 Published 05 August 2022 ABSTRACT The research investigates the effects of ground surface temperature (air temperature) on soil temperature at a depth of 5 cm. The study covers a period of fourteen (14) months from May 2010 to June 2011 in Akure, Southwestern Nigeria. With the aid of an automatic weather station, temperature readings were taken at a depth of 5 cm below the soil surface at five (5) minute intervals daily. It was also observed that many analyses of soil temperature are based on the theories of heat flow and energy balance. The study reveals that surface temperature has a weak effect on soil temperature. The best correlation coefficient obtained for the study period is about 0.56 with a quadratic equation of order 2 at 5% significance level. This implies that air temperature cannot be solely used to predict soil temperature at a depth of 5 cm. A study of diurnal variation reveals that air temperature is usually higher than soil temperature during the day, and vice versa. The study also revealed that surface and soil temperatures are generally lower during the wet months when compared with the dry months. The wet season average daily temperatures are 23.42 o C and 27.69 o C for air and soil while the corresponding dry season values are 33.92 o C and 30.91 o C respectively. The results are recommended for agricultural purposes such as determination of soil and environmental conditions for crop production. Keywords: Heat flow; energy balance; surface temperature. Original Research Article