Fertilizer Residence Time Affects Nitrogen Uptake Efficiency and Growth of Sweet Corn

Understanding plant N uptake dynamics is critical for increasing fertilizer N uptake efficiency (FUE) and minimize the risk of N leaching. The objective of this research was to determine the effect of residence time of N fertilizer on N uptake and FUE of sweet corn. Plants were grown in 25 L columns during the fall and spring to mimic short‐term N uptake dynamics. Nitrogen was applied either 1, 3, or 7 d before a weekly leaching event, using KNO 3 solution (total of 393 kg N ha −1 ). Residence times ( t R ) were t R –1, t R –3, and t R –7 d before weekly removal of residual soil N. Plant N uptake was calculated by comparing weekly N recovery from planted with non‐planted columns. During the fall, N uptake values at 70 d after emergence were 59, 73, and 126 kg N ha −1 During the spring, corresponding values were 54, 108, and 159 kg N ha −1 A linear response of plant growth and yield to the t R was observed under cooler conditions, whereas a quadratic response occurred under warmer conditions. There was correlation between root length density and yield. It is concluded that increasing N fertilizer residence time, which is indicative of better irrigation practices, enhanced overall sweet corn growth, yield, N uptake, and FUE, consequently reduced the risk of N being leached below the root zone before complete N uptake.