As mentioned earlier, study for inhibition of microbial growth in soil typically employs a solarization process, chemicals or hot water. The chemical method is the most common and easy technique, but its not an environmentally friendly. The solarization process is dependent upon local climate and weather, taking an average of 46 weeks to inhibition for microbial growth in soil with 10 cm of maximum depth in soil. Hot water dropping is an environmentally friendly method that can use free energy from solar energy sources and can be reduce the inhibition time when compared to the solarization method with taking an average of 46 h on the sunshine time. However, the temperature average more than 35 oC which can be inhibit microbial growth in soil [อ้างอิง]. In this research is focus on the method for increase high enough degrees of soil temperature to inhibit the growth of R. solanacearum in soil, which decrease the working time to less than hot water dropping method (46 h). Thus, the high pressure method (pressure head) of hot water have been selected for increase
the temperature of soil with shorter time in this research study. The current research aims to investigate the heat transfer in soil to inhibit microbial growth in soil with hot water releasing underground by using pressure head of liquid.