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Fluid Journal : Fluid Journal 2005-2007
8 Fluid Journal EARLY SPRING 2007 DR. G. LAFOND, S. BRANDT, W. MAY, C. HOLZAPFEL AND DR. A. JOHNSTON Nitrogen is the most limiting nutrient in crop production. When the increasing need for environmental sustainability is combined with increasing demands for food and fiber and current global trade policies, and then all of that is superimposed on the need of producers to remain economically viable, attention has to be focused on the efficiencies at all levels of the production cycle. Nitrogen use efficiency (NUE) is only about 33 percent and much attention is currently being focused on ways to improve NUE. Nitrogen fertilizer production is very energy intensive and N can easily be lost from the cropping system through Post-emergent Nitrogen Applications Have Potential for Increasing N-Use Efficiency in Spring Grains Provisos are that some starter N is applied at time of seeding, but the amount of starter N is dependent on how much risk the grower is willing to assume by going with more N after crop emergence. SUMMARY The results from the Indian Head, SK site showed that a minimum of 33 percent of the total nitrogen (N) fertilizer required for spring grains should be applied at seeding time to ensure that none of the yield potential is lost. We speculate that 50 percent of the total N required should be applied at seeding to further minimize the risks. With spring wheat, applying the N as late as the 5-leaf stage did not appear to reduce grain yields. With canola, applying the N as late as the start of flowering did not affect grain yields. In conclusion, post- emergent N applications have the potential of increasing the flexibility of N management, providing that some starter N is applied at time of seeding. The proportion will be dictated by the agro-ecological zone and by the risk that the producer is willing to assume.
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