Pre-Plant Nitrogen Fertilizer Uptake and Partitioning in Furrow-Irrigated Corn

Nitrogen fertilizer is routinely required to produce maximum corn (Zea mays L.) yield in the mid-South. Two field experiments were established to evaluate the fertilizer-N recovery and partitioning of N-15-labeled urea applied pre-plant to furrow-irrigated corn at the R6 growth stage. Pre-plant N-15-labeled fertilizer was applied at rates of 0, 34, 67, and 100 kg N ha(-1) using application methods including an incorporated, surface broadcast, and water-furrow application. Additional non-labeled N was applied in-season at the V6 growth stage so that the season-total N fertilizer rate applied in all treatments receiving N was equal to 270 kg N ha(-1). The mass fertilizer-nitrogen recovery (MFNR) and Delta MFNR increased as pre-plant N rate increased in both years. Pre-plant N rate and application method displayed no significant influence on total-nitrogen (TN) uptake when additional N was applied in-season. Fertilizer-N recovery efficiency (FNRE) of pre-plant N ranged from 14.8 to 39.9%. Of the MFNR of pre-plant N at maturity, 75% was taken up by the corn aft er the V6 growth stage. The 67 kg N ha(-1) application rate of pre-plant N was the lowest N rate that simultaneously maximized yield and FNRE both years. Pre-plant N fertilizer that was applied broadcast or incorporated resulted in the greatest yield, percent TN in the grain, and percent MFNR in the grain at maturity in both years. Producers are encouraged to incorporate or broadcast 67 kg N ha(-1) or less pre-plant for furrow-irrigated corn when additional N is applied in-season.