Efficiency of Different Soil Sterilization Approaches and Their Effects on Soil Particle Size Distribution

Soil microorganisms play an important role in many soil processes. In order to clarify soil microorganism functions in soil reactions, efficient soil sterilization approaches are required for conducting paired experiments in soils with and without microbes. Soil physical structure such as soil particle size distribution is critical for the soil system. However, few studies have analyzed the effects of different soil sterilization methods on soil physical structure. Thus, this study aims to study the efficiency of different sterilization methods as well as their effects on soil particle size distribution. Four sterilization approaches of autoclaving, oven heating, ultraviolet irradiation, and microwave heating have been tested for their efficiency and effects on soil particle size distribution via a one-week soil incubation experiment. Oven heating was the most efficient in sterilizing soils with the highest efficiency for both bacteria (99.35%) and fungi (98.28%). While autoclaving and microwave irradiation was less efficient in sterilizing soil bacteria (efficiency at 86.75% and 87.73%). In addition, all sterilization methods decreased soil fine and medium sand fractions. Oven heating and ultraviolet irradiation led to greater silt-size particle contents, while autoclaving and microwave sterilizations increased coarse-sand-size particle contents. Oven heating method was the most efficient, while microwave method also had the potential to improve.