## 1 Introduction  
Plant stressors impact yields of both summer and winter crops, including canola, wheat, sugar cane, corn, cotton, and rice. The main abiotic plant stressors that impact crop growth include fluctuating temperatures, soil pH, salinity, soil water availability (drought), diurnal cycling changes, and availability of soil nutrients [1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12]. Summer crops grown in Australia, including rice, cotton, and sugar cane, require high volumes of water, which is applied using irrigation systems. In Australia, winter crops, including canola, wheat or maize are planted in rotation with the aforementioned summer crops and grown [13; 14; 15] using the seasonal precipitation and residual moisture from the irrigation season. Summer irrigated crops are of high economic value, producing a combined export income between 55.8-6.8 billion AUD annually [16; 17; 18], whilst their winter counterparts had an export value of $10.2 billion AUD in 2016 [19]. The irrigation strategies for these crops can either be 'high' or 'low' depending on the crop plant being cultivated, season or soil profile [6; 15; 20; 21]. High irrigation strategies primarily refer to flood irrigation (largely water inefficient), whereas low water types include subsurface drip irrigation, sprinkler irrigation, localized irrigation, and lateral move irrigation (highly water efficient) [22; 23]. Currently, flood irrigation is the main practice used in Australia for delivering consistent large volumes of water to maintain a moist soil environment that propagates crop growth [24]. Throughout the growing season, irrigated soils fluctuate between aerobic and anaerobic states based on water availability in the soil. The type of irrigation strategy will also have profound effects on the soil temperature, soil pH, water salinity, soil water availability (water activity), light intensity, and availability of trace elements (Figure 1) [1,24]. Thus, the influence of irrigation strategies on the abiotic characteristics of agroecosystems can lead to the formation of abiotic stress towards the cropped plants [25]. Trace element availability is an abiotic stressor that directly impacts growth and yield of cropped plants and is influenced by irrigation strategy [26]. Trace elements are found in small concentrations (mg/kg\({}^{-1}\) or less) in the environment and include: copper (Cu), cobalt (Co), zinc (Zn), iron (Fe), nickel (Ni), manganese (Mn), vanadium (V), selenium (Se), and molybdenum (Mo). These are essential as they act as cofactors for enzymatic activities and other metabolic processes in plants [27]. Irrigation affects trace element availability by solubilizing these metals, changing soil pH, changing soil transformation rate, and subsequent redox changes associated with soil compounds [6,28]. Differences in trace element availability are observed between flooded soils and dry soils, and it is known that Zn solubility differs greatly between flooded anaerobic soils compared to aerobic dry conditions [29]. This change in trace element solubility has become a major concern for the production of rice crops as cultivation practices change. As irrigated soils dry out and become aerobic, associated pH and redox changes render some trace elements unavailable--referred to as 'nutrient lock out' [27,30,31]. Moreover, the bioavailability of non-essential heavy metals, including arsenic (As), cadmium (Cd) and mercury (Hg), is also affected by changes in anaerobic/aerobic cycling, and these metals are typically more toxic at much lower concentrations compared to essential trace elements [27]. Metal levels in soil can range from less than 1 ppm (0.0001%), through to 100,000 ppm (10%) or higher in extreme cases [32,33]. Fluctuations of metal levels in the environment alters their availability to the biota.