Microwave soil treatment improves weed management in Australian dryland wheat

Herbicide resistance has prompted the development of a chemical-free weed management practice in no-till farming systems. In this study, we examined the effect of pre-emergence microwave (MW) soil treatment for weed management in a no-till wheat production system in Australia. One-time MW soil treatment (2.45 GHz, 600 W, 120 s) was applied to plots that were arranged in a randomized complete block design with five replicates. The MW energy was projected through a horn antenna with aperture dimensions of 5.5 cm x 11 cm into the topsoil (0 to 6 cm) horizon. The applied MW energy density in the treated plots (2.6 m(2)), which was calculated by Simpson's numerical surface integral approximation, was approximately 560 J cm(-2). This achieved an increase in soil temperature of about 75 degrees C to 80 degrees C. This temperature induced a 65% to 80% reduction in weed establishment through thermal devitalization of the weed seedbank, compared to the untreated control plots. In addition, a substantial increase in wheat grain yield of 39.2% was achieved through MW energy application (7.8 t ha(-1)) compared to non-MW conditions (5.6 t ha(-1)). In summary, this non-chemical weed management strategy promises to effectively control herbicide-resistant weeds and sustain dryland wheat yields