Wednesday, November 4, 2009
Convention Center, Exhibit Hall BC, Second Floor
There is growing interest in applying N to corn in response to remotely sensed plant N status. Remote sensing of N status appears to be most successful after canopy closure (V10), but needs to be before reproduction starts (R1) for optimal N use and lowest NO3 leaching under natural rainfall (Jaynes and Colvin, 2006). While the yield benefits of sidedressing N at V10 are well documented, little information is available on the impacts to water quality. We compared grain yields and NO3 losses in drainage water as a result of applying N either once after plant emergence or equally split between just after emergence (V1) and early crop growth (V6 or V10). Nitrogen treatments consisted of 138 kg ha-1 applied post-emergence (V1), and 69 kg ha-1 applied post-emergence and again at either V6 or V10. Grain yield for corn and soybean, grown in a 2-yr rotation, and drainage water NO3 concentrations and flow were measured on replicated tile-drained plots in a producer’s field from 2006 through 2009. Results from yield and water quality measurements will be reported.