This research aimed to investigate the effects of soil density and develop a solar heater system with high water temperatures to inhibit microbial growth in soil with hot water dropping. The soil density was 300, 350 and 400 kg/m(3). The hot water system consisted of an Asymmetry Compound Parabolic Concentrator (ACPC), Compound Parabolic Concentrator (CPC) and Flat-Plate Solar Collector (FPSC). The proposed system was designed to inhibit microbes of R. solanacearum. The effects of soil density, a solar hot water system and volume of hot water dropping flow rate on heat transfer in soil, depth level and working time were tested in comparison with solarization. The solar hot water system provided a high temperature of greater than 70 degrees C. The high temperature of the hot water and low density of the soil had a significant effect on performance of inhibition of microbes (99.99%) in soil, with 30 cm of depth level and 2 h of working time. However, a volume flow rate of hot water dropping of 15-17, 20-22 and 25-27 ml/min had no effect on heat transfer in the soil. (C) 2017 Published by Elsevier Ltd.