70196 Pre-Tassel Nitrogen Applications for Improving Corn Yields in Mississippi- Fact or Fiction?.

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See more from this Session: Professional Poster – Crops
Sunday, February 5, 2012
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M. Wayne Ebelhar, Delta Research & Extension Center, Mississippi State University, Stoneville, MS and Davis R. Clark, Delta Research and Extension Center, Mississippi State University, Stoneville, MS
Traditionally, nitrogen (N) applications for corn in the Midsouth has involved either a single or split application just prior to planting or after crop emergence followed by a sidedressed application at the 5-6 true leaf growth stage (PP-SD). Producers have been interested in later N application, up to tasseling.  A field evaluation of corn response to tassel nitrogen (TN) was initiated in 2009.  The standard (PP-SD) N treatments ranged from 134 to 314 kg N ha-1 with 134 kg N ha-1 applied at planting and 0, 45, 90, 134, and 179 kg N ha-1applied at the 5-6 leaf stage.  Pre-tassel N was applied at rates of 0, 22, 45, and 67 kg N ha-1 as urea.  The N was hand-applied to simulate an aerial application.  The treatments were a factorial arrangement of PP-SD N (5 levels) and TN (4 levels) in a randomized complete block design with four replications.  Cultural practices were maintained uniformly across the study.  Grain yields, harvest moisture, bushel test weight, and 100-seed weights were determined from each plot.  Grain yields have been significantly increased with TN especially at the lower PP-SD N rates.  Although yields have been quite different across years, the response to TN has been evident in each year.  In 2009, corn yields ranged from 3.78 to 11.06 Mg ha-1 with the highest yields were measured where the highest N rates were applied.  The TN applications increased grain yields by 1.60 to 2.16 Mg ha-1 when averaged across the PP-SD N rates.  In 2010, the highest yield was obtained with 269 kg N ha-1 when average across the TN rates.  Actual yields ranged from 8.58 to 14.18 Mg ha-1.  When averaged across all N rates, adding 22 to 45 kg N ha-1 significantly increased grain yields by 0.75 to 1.13 Mg ha-1.  In 2011, optimum yields (11.32 to 11.85 Mg ha-1) were obtained with 269 kg N ha-1 averaged across TN rates. Adding TN increased yields from 12.1 to 18.0% when averaged across the PP-SD treatments.