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Fluid Journal : Fluid Journal 2005-2007
EARLY SPRING 2007 Fluid Journal 9 1) leaching, 2) NH3 volatilization, 3) surface runoff, and 4) denitrification, not to mention the nitrous oxide emissions during the nitrification process. Nitrous oxide is a very potent greenhouse gas and use of N fertilizers has a direct effect on emissions, the extent of which varies with agro-ecological zones. Nitrogen fertilizers also represent a significant proportion of the overall variable cropping costs and account for over 65 percent of all energy requirements needed to grow a crop. The recent increases in oil and natural gas prices, N supply, and demand factors are having a direct impact on the price of N fertilizers. These economic conditions are stimulating many agronomic questions related to management practices needed to attain higher NUE. A number of studies have been conducted in the last few years to examine the merits of post-emergent N applications using UAN solution and surface dribble applications as a way to apply N closer to the time of crop needs. Studies have shown that this approach was feasible but it was not without risk and never was better than putting all the fertilizer on at the time of seeding as is currently done in a one-pass, no- till seeding and fertilizing system. The studies concluded that the unpredictability of rainfall increases the risks of surface dribble bands because some rainfall is required to move the fertilizer into the soil. In 2003, where no significant rainfall was experienced for the critical part of the growing season, yield losses were experienced with post- emergent N applications due to the inability of the crops to access the N stranded at the surface. The studies also showed that even Figure 1. Effect of N starter levels on spring wheat yield via mid-row banding, Indian Head, SK, 2004 Figure 2. Effect of N starter levels on grain protein of spring wheat via mid-row banding, Scott, SK, 2004. 33 35 37 39 41 43 45 % N at Seeding Check 100 67 50 33 0 Yield bu/A 0 13 13.5 14 14.5 15 15.5 16 % N at Seeding Check 100 67 50 33 0 Protein %
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