Microwave Heat Disturbance Alters Soil Microbial Communities from Three Australian Agricultural Lands

Abstract

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, or if this positively (e.g., soil disinfestation) or negatively (e.g., a reduction in ecosystem services) affects soil health. 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 (dryland, temperate and irrigated farming systems) to MW heating, and monitored the fungal and bacterial communities immediately after heating as well as 14 and 28 days later. 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 suggest that bacterial communities may be less resilient to MW soil heating required for weed seedbank deactivation than fungi, and highlight the need to understand how microbial functions are affected by this management technique in the long term.

Keywords: new pest control technologies, microwave disinfestation, different farming systems, soil microbes, communities' recovery