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Fluid Journal : Spring 2017
7 The Fluid Journal Spring 2017 Impact of Nitrogen Timing On Corn Production This paper originally presented at the North Central Extension-Industry Soil Fertility Conference, Nov. 2-3, 2016, Des Moines, IA. The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Spring 2017 • Vol. 25, No. 2, Issue #96 Dr. John E. Sawyer, Dr. Daniel W. Barker and Mr. John P. Lundvall Summary: There are many opportunities for N applications to be accomplished during the spring season, with options for successful pre-plant through midseason timing, along with tools to adjust rates. The potential frequency of soil and weather conditions that may impact optimal N timing, along with time and equipment to accomplish applications, should be considered when implementing sidedress/split N application systems. ▼ DOWNLOAD Water quality issues have renewed interest in timing of nitrogen (N) application as a means to improve use efficiency in corn and reduce losses. Improved economic return is also desired as N fertilization is one of the most costly inputs to corn production. Time of fertilizer application is a component of the site-specific 4R nutrient management stewardship programs. In Iowa, the Nutrient Reduction Strategy has a 7% (37% std. dev.) nitrate-N reduction with a 0% (3% std. dev.) corn yield change for sidedress compared to preplant N applications (SP 0435A). A main area of emphasis for sidedressing is the potential to apply N during the time of rapid plant N uptake, reducing the time applied N is subject to potential losses with wet conditions. Sidedress and in-season N application may also allow for adjustment of application rate. However, producers can be reluctant to apply N in-season as they are busy with other operations, concerned about yield loss due to early N stress, or concerned that wet weather will prevent application. Delay in sidedress applications can reduce yield, but the potential can be mitigated with use of split application where part of the N is applied at or before planting. However, as corn accumulates approximately 70% of total N uptake by R1 (Woli et al., 2016), N limitation during vegetative growth can affect yield potential. Sidedress (split) application has historically shown consistent benefit on coarse textured soils. On medium- to fine-textured soils, the yield, water quality, and economic return have not been consistent. This report will summarize studies conducted in the past twelve years on the effect of N application timing on corn production.