مرکز منطقه ای اطلاع رساني علوم و فناوري - The determination of soil temperature and thermal diffusivity

Abstract :

Changes in the soil temperature and thermal diffusivity conditions are one of the most important components of soil microclimate and have a considerable impact on changes iÖn soil properties and plantdevelopment processes. This study is carried out in a field covered with grass (I. experimental field) andanother field covered with peach trees (II. Experimental field) in Çarşamba district of Samsun. The soiltemperatures of each 10 cm from soil surface to 100 cm depth were measured daily in the experimentalfields at 7^00, 12^00, 18^00 hours between august 21 and september 19, 2011. Some thermal properties of soils such as; daily soil temperature changes and due to these changes heat diffusivity, amplitude, andcomparison between theoretical soil temperatures estimated from the solution of heat transfer equationand daily measured soil temperatures were investigated. In the I. and II. experimental fields, daily soiltemperatures measured at 0-50 cm soil depth at 7^00, 12^00 and 18^00 hours were 16.5-24.0; 21.0-34.0; 19.5-27.0°C and 16.5-23.0; 19.0-27.5; 19.0-24.8°C, respectively and that measured at 50-100 cm soil depth were 19.1-23.0; 21.0- 25.5; 19.2-25.0°C and 18.9-22.0; 19.2-24.5; 19.0-24.0°C, respectively. Generally, changes in soil temperatures were less near the soil surface and much less in deeper soil layers ( 50 cm).Amplitude values in the I. experimental field were 2.03-5.60ºC at the soil surface and between 0.90 and 3.07ºC at the layers deeper than 10 cm, they were 1.97-2.77ºC at the soil surface and between 0.94 and 2.46ºC at the layers deeper than 10 cm in the II. experimental field. Mean heat diffusivity in 0-100 cm soil depth were determined between 0.0835 and 0.8830 cm^2 sec^-1 in the I. experimental field, and between 0.2578 and 1.9692 cm^2 sec^-1 in the II. experimental field. The relative error between soil temperaturesestimated from the solution of heat transfer equation and daily measured soil temperatures weredetermined between 0.015 and 0.089.