An experiment was conducted to study the effect of modified radiation climatic conditions on soil heat flux in wheat cv PBW-226sown on 21st November 1996 below 8 years old Eucalyptus tereticonis planted in a Nelder wheel design for providing different microclimatic conditions to the intercropped wheat. The angle between the two adjacent rows was 240. The area per tree was 30m2. Total number of trees was 105. Net plot size of one treatment was 248m2. Diurnal soil heat was measured in T1 (00-240), T2 (1200-1440), T3 (2400-2640) and control plot simultaneously at tillering, flag leaf emergence, ear head emergence and maturity. Soil heat flux varied diurnally and was highest in control at all stages of crop except noon in some cases. Fluctuating soil heat flux was observed below trees.