Figure 7. Potato yield versus N rate for more recent studies that included at least 3 levels of N, with other nutrients held constant. Some markers are overlapping. Blue vertical line is the current N rate recommendation; red lines are the 90 and 95% relative yield levels. The first 11 studies were Hochmuth, et al. 1993b; Other reports are Chen and Hutchinson, 2008; Pack et al., 2006; Hutchinson, 2005; Hutchinson et al., 2003; and Munoz, 2004.