Global Journal of Agricultural Innovation, Research & Development, 2018, 5, 1-14 1 E-ISSN: 2409-9813/18 © 2018 Avanti Publishers Microwave Weed and Soil Treatment in Agricultural Systems Graham Brodie * , Muhammed Jamal Khan, Dorin Gupta and Sally Foletta Dookie Campus, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne Abstract: Weeds are the major hindrance in crop production, costing approximately AU$4 billion annually in Australian gain production systems, in 2006. Herbicide resistance is also becoming a global issue; therefore, there is a growing need for alternative weed control methods. Several thermal and non-thermal methods are possible. The thermal method of microwave weed management has been explored for some time. This paper provides a brief summary of the research associated with this technique. Keywords: Weed, soil, microwave, herbicide resistance, crop production. 1. INTRODUCTION Weeds are the major hindrance in crop production. They compete for light, space, nutrients, moisture and CO 2 , significantly declining crop yields. Modern no-till cropping depends on herbicides for weed management. Herbicides are classified by their mode of action, as outlined in Table 1. In Australian agriculture, the total estimated direct cost of weed management and loss in crop productivity, due to weeds, was estimated, in 2006, to be about AU$4 billion annually [1]. Similarly, in 1995, Pimentel [2] estimated the indirect costs of chemical pest management to be approximately US$5.8 billion annually in the United States. Scaling this indirect expenditure to the Australian population, and accounting for some inflation in costs over time, currently yields about AU$0.5 billion annually. In terms of present costs, the combined direct and indirect costs of chemical weed management for Australian broad acre cropping is estimated to be approximately AU$6.2 billion annually (≈AU$280 ha -1 across the cropping area of the country). 1.1. The Growing Threat to Herbicide Use Harper [4] predicted the development of herbicide resistance over 60 years ago; suggesting that the development of resistance is an inevitable consequence of reliance on chemicals for weed control [5]. Globally, there are now over 400 weed species that have developed resistance to 160 herbicides from the various chemical groups (Table 1) and annually 9 new weed biotypes are reported as becoming herbicide resistant [6]. For example, Bagavathiannan et al, [7] reported glyphosate resistance in barnyard grass *Address correspondence to this author at the Dookie Campus, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne; Tel: +61 3 5833 9273; Fax: +61 3 5833 9201; E-mail: grahamb@unimelb.edu.au (Echinochloa crus-galli L.) in 2011, while ryegrass (Lolium rigidum), in Australia, has developed resistance to multiple chemical groups [8]. Thornby and Walker [9], determined, by simulation and field observations, that continuous use of glyphosate induced resistance in barnyard grass (Echinochloa colona) within 15 years. The International Agency for Research on Cancer (IARC), which is part of the World Health Organisation (WHO), has also concluded that glyphosate is probably carcinogenic to humans [10]. This announcement has generated considerable debate in the media, concerning the use of herbicides. Other authors have also highlighted the potential hazard to human health of long term exposure to herbicides and pesticides [11- 16]. This almost led to glyphosate being banned in the European Union; however, it was reregistered for agricultural applications. 1.2. Understanding Crop Response to Herbicide Weed Management System analyses often shed useful light on the impact of change on agricultural production. A system transfer function, which relates crop yield potential to herbicide application, has been derived [17]: (1) Where, W a = I . W 1 − N − D o ( ) − E m + I m ⎡ ⎣ ⎤ ⎦ , G = e ct 1 + e− t −t o d ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ ⎡ ⎣ ⎢ ⎢ ⎤ ⎦ ⎥ ⎥ , B = .1 − S. e − ag 2 2 + S. e − ag 2 2 −λ H ⎡ ⎣ ⎢ ⎢ ⎤ ⎦ ⎥ ⎥ . The sensitivity of yield potential to time can be deduced by differentiating this transfer function with respect to the number of weed generations (g):