“…Additionally, studies have also attempted to quantify optimum site-specific seed densities (Licht et al, 2017), which may represent a more economically impactful management change in many cropping systems compared to changes in nutrient applications. Variable rate zones defining different application rates have been generated using precision agriculture data sources including yield monitor maps (Adamchuk et al, 2004;Basso et al, 2016;Maestrini and Basso, 2018), remotely sensed data (Hong et al, 2006;Basso et al, 2016;Gao et al, 2018;Jin et al, 2019), gridded soil sampling (Fleming et al, 2000), digital soil maps (Bobryk et al, 2016), topography (Long et al, 2015;Walters et al, 2017), and real-time optical sensors (Raun et al, 2002;Tremblay et al, 2009;Kitchen et al, 2010;Stefanini et al, 2018).…”