Assessing the Impact of Microwave Treatment on Soil Microbial Populations

Microwave soil treatment can kill weed plants and their seeds in the soil. It has also been demonstrated elsewhere that microwave soil treatment can kill nematodes in the soil; however few studies have considered the effect of microwave soil treatment on other key soil biota. This study explored the effect of microwave soil treatment on soil bacteria, fungi, and various protozoa. The research used a series of experiments using different techniques to verify the effect of varying degrees of microwave treatment on these soil biota. Microwave treatment reduces bacterial populations in the top layers of soil, but populations that are deeper in the soil are relatively unaffected. Bacterial populations increased significantly within a month of microwave treatment. E. coli populations experienced a 10-5 reduction in numbers in the top layer of soil by 500 J cm-2 of microwave energy; however other soil bacteria survived over 3000 J cm-2 of microwave energy applied to the soil surface, suggesting that some species are more susceptible to microwave treatment than others. No significant response of soil fungi, ciliates, amoeba and flagellates could be attributed to a microwave dose response.