Effect of Nitrogen Application Timing on Corn Production Using Subsurface Drip Irrigation

The use of subsurface drip irrigation (SDI) in row-crop agriculture is increasing because of potential increases in water and nutrient use efficiency. Research-based information is needed to manage N 'applications through SDI systems in field com (Zea-mays L.) production. This study was conducted to assess the effect of different inseason SDI system N application timings :on corn produ6tion and residual soil N0 3-N at the University of Nebraska-Lincoln West Central Research and Extension Center in North Platte, Neb, on a Cozad silt loam (fine-silty, mixed, mesic Fluventic Haplustoll). We evaluated the effect of three N application timing methods (varying percentages of the total N rate [48% of total N] applied at the VIO, VT, and R3 growth stages, in addition to uniform N applications [52% of total NJ over all treatments at preplant, planting, and V14 growth stage) at two N application rates (University of Nebraska-Lincoln [UNL] recommended rate and the UNL rate minus 20%) on corn grain and biomass yield and end-of-study distribution of residual soil N0 3-N. In 2006, there were no significant differences in corn grain yields between the two N application rates. In 2007, the grain yield under the UNL.recommended N rate was significantly higher (190 kg ha-1) than the UNL-minus-20%N rate. The average grain yield for this study was close to the predicted yields (based on average 5-year historic yields + a 5% yield increase), indicating that ,orn production under SDI is satisfactory. In 2006 and 2007, grain yield and biomass production for the N application timing treatments were not significantly different (P > 0.05). The application of 13% of the total N at as late as R3 did not result in decreased yields. The lack of response to differentN application timing treatments indicates that there is flexibility in N application timing for corn production under SDI. The distribution of N0 3-N in the 0to 0.9-m and 0.9to 1.8-rn soil profiles was not significantly different among all the treatments.