Forage Yield and Silage Quality of Dual-Purpose Corn Hybrids in Two Levels of Urea Fertigation

The experiment was completed to evaluate the responses of forage yield and silage quality of dual-purpose corn hybrids to urea fertigation. For this purpose, two studies were conducted each as a split plot experiment based on a randomized complete block design with three replications at two locations in research farms of College of Agriculture, Isfahan University of Technology, Isfahan, Iran, in 2016.  Two levels of nitrogen fertigation including 150 and 200 kg ha-1 in Lavark Research Field -Najafabad city; 200 and 250 kg ha-1 in Shervedan Research Field- Flavarjan city with urea fertilizer, N= 45%, and 20 forage-grain corn hybrids were designed as main and sub plots, respectively. The results showed that the increased application of nitrogen fertilizer improved biological yield in Shervedan field and dry matter percentage and silage yield in both locations, but had no effect on the ratio of forage components including leaves, stems and ears to total forage weight. The protein concentrations of silage hybrids increased significantly as a result of increasing nitrogen application in Shervedan. Also, with increasing nitrogen fertilizer, the amount of ash in both locations increased, but insoluble fibers in neutral detergent and insoluble fibers in acidic detergent decreased. The interaction effects of nitrogen × hybrid on silage acidity was significant in Shervedan. At Shervedan field, the highest biological yield (298,000 kg/ha) and silage dry matter percentage (29.8%) were observed in AGN591 and Whichita with application of 250 kg/ha N-fertilizer. AGN756 had the highest biological yield (27,200 kg/ha) and silage dry matter percentage (28.6%) upon application of 200 kg/ha N-fertilizer in Lavark field station. It seems that in each region, by using the appropriate amount of nitrogen fertilizer and selecting high-potential yield hybrids, both acceptable quantitative and qualitative yields of corn silage can be achieved.