EVALUATION OF NITROGEN APPLICATION METHODS AND RATES WITH NUTRISPHERE-N ON CORN IN SOUTHEASTERN COASTAL PLAINS

Application method of Nitrogen (N) and Nutrisphere-N may influence corn (Zea mays L.) growth and yields under dryland conditions. The objective of this study was to determine the effect of two N application methods (all at planting and split application with 35 kg N ha^-1 applied at planting and remaining N at V6 stage) and five N rates (0, 45, 90, 135 and 180 kg N ha^-1) with and without Nutrisphere-N polymer on dryland corn near Blackville, SC from 2010 to 2012. Compared to control, Nutrisphere-N polymer improved corn grain yield by 33.3 and 29.5% at 90 and 135 kg N ha^-1 applied at planting and 12.1, 12.9, 22.0 and 31.2% at 45, 90, 135 and 180 kg N ha^-1 applied in split applications, respectively. Chlorophyll improved in corn leaves by 19.3% at 8 weeks after planting with application of 45 kg N ha^-1 and Nutrisphere-N at planting. Split N application with Nutrisphere-N slightly improved chlorophyll in corn leaves. Nutrisphere-N increased plant LAI at 8 weeks after planting by 10.2% at 135 kg N ha^-1 in split applications and LAI at 16 weeks after planting by 50.4, 56.2, 59.4 and 70.7% at 45, 90, 135 and 180 kg N ha^-1 with split applications, respectively. Plant NDVI at 16 weeks after planting corn improved with Nutrisphere-N by 9.3, 11.5, 13.0 and 9.2% with N applied at planting and 16.0, 12.9, 10.2 and 14.3% with split N applications at 45, 90, 135 and 180 kg ha^-1, respectively. Nutrisphere-N increased grain N by 4.5% at 135 kg N ha^-1 applied to corn at planting and 5.2% at 90 kg N ha^-1 applied in split applications. Generally, N applications with Nutrisphere-N positively improved growth parameters and yields of corn.