Effect of Ensiling Time on Distribution and Losses of Nitrogen in Corn Silage Treated with Limestone and NPN

Small bag silages were prepared in 1965 and 1966 to determine changes in nitrogen distribution when urea, urea-limestone, limestone and diammonium phosphate were added to the corn plant material at ensiling time. Representative bags were analyzed after 0, 2, 8 and 180 days of ensiling in 1965 and 0, 3 and 42 days in 1966. Analyses were made on material coarsely ground after freezing in liquid nitrogen. Further treatment of this material by ball-milling resulted in losses of nitrogen. There was an apparent loss of true protein nitrogen during the ensiling process, presumably due to proteolysis. Ammonia nitrogen increased slightly in all silages in 1965 and increased considerably more in urea treated silages in 1966. At no time, however, did ammonia contribute more than 12% of the total nitrogen. Urea nitrogen decreased only slightly, if at all, in 1965 but decreased significantly during ensiling in 1966. Nevertheless, the majority of the urea remained unhydrolyzed after ensiling was complete. The diammonium phosphate treated silage had considerable quantities of ammonia present but showed no decrease with time.