Assessing the effects of microwave heat disturbance on soil microbial communities in Australian agricultural environments: A microcosm study

Weeds reduce agricultural productivity by competing for resources intended for crops. Recently, the deactivation of weed seedbanks by microwave (MW) radiation has been developed as a chemical-free weed management practice. It is unknown, if these extreme heat disturbances permanently alter the soil microbiome of different farming systems. We performed a microcosm experiment to quantify the immediate and short-term effect of MW heating on the soil microbiome. We exposed three different soil types (representing dryland, temperate and irrigated farming systems) to MW heating, and monitored the fungal and bacterial communities over a month of recovery. Bacterial and fungal community composition were strongly dependent on the soil of origin. Following MW heating, bacterial and fungal richness decreased in all soils and did not recover during the period studied (four weeks). Notably, in all soils, bacterial communities became more dissimilar to each other following disturbance, but in fungi, this depended on the soil of origin. These results highlight the importance of considering the resistance and recovery of the resident soil microbiota in developing long-term sustainable MW-based weed management system.