Nitrogen Sources for Cotton and Corn and Ammonia Volatilization.

Because of high fertilizer N prices, growers are interested in using less expensive urea sources of N and using fertilizer additives to reduce ammonia volatilization losses.  An experiment  on a Lucedale fine sandy loam in Central Alabama was conducted in 2007 and 2008 to compare traditional and non-traditional sources of N for high-residue, conservation tilled corn and cotton under non-irrigated conditions.  Ammonia volatilization was monitored for two weeks after topdressing with selected fertilizer materials and fertilizer additives.  A severe drought in 2007 resulted in no harvestable corn and cotton yields.  A moderate drought in 2008 resulted in low  crop yields.   However, the hot, dry conditions in both years allowed for potentially high volatilization losses of ammonia-N which were observed in 2007 but not in 2008.  In 2007, 80 percent of the applied N was lost from urea when applied to a soil with a heavy rye residue.  Agrotain® applied with the urea reduced volatilization losses by almost half.  In 2008, very little N loss was measured from urea and most of this occurred within a few days of application.