HEAT FLUX IN SANDY SOIL AND ITS RELATIONS WITH SOIL AND AIR TEMPERATURE

A heat flux plate was installed at 0.05m depth and thermowires were installed at 0.05 and 0.3m depths in sandy soil withgrasses of the surface at Ismailia Agriculture Research Station.Data of soil heat flux (G) (W/m2) and soil temperatures wererecorded every fifteen mints to represent 96 readings/day and airtemperatures (oC) were recorded every one hour. Finally, twentyfour values for soil heat flux, soil temperatures were calculatedand air temperature were recorded along a year. The objectivesmust study the soil heat flux at 0.05m depth and its relation to soiland air temperature. Also to calculate heat flux at 0.3m depth anddetermined the relation between G at 0.05m and G at 0.3m.The obtained results showed that soil heat flux values(W/m2) at 0.05 m depth were higher at the day time with theirpeaks were at the mid day. The values became negative at nightand early morning in the months of December, January, Februaryand March, while the values became positive and low at earlymorning in the other months.Soil heat flux had been affected by both soil and airtemperatures. The temperatures of air were more effective thansoil temperatures of all months except for May and June. While, inMarch both temperatures had more or less similar effect on soilheat flux.The correlation coefficients and regression equations weresignificant between soil heat flux and either soil or airtemperatures during the tested period.The values of calculated soil heat flux (G) at 0.30 m depthwere less than those of measured soil heat flux (G) at 0.05 m,inspite of the significant values of correlation and regression between each other.