Within-Row Variability Resulting From Diagonal Versus Parallel Pre-Plant NH3 Applications.

Corn (Zea mays L.) production relies heavily on nitrogen (N) fertilizer, and much of the N fertilizer is applied as pre-plant anhydrous ammonia (AA). Indiana farmers typically apply their pre-plant AA at an angle to the future corn row, but the latter approach introduces variable compaction and variable N concentration patterns within the corn row. Field studies were conducted between 2010 and 2012 near West Lafayette, IN to compare the effect of pre-plant AA placement (traditional diagonal application versus parallel-to-row but offset application) on within-row uniformity of corn plant response. These patterns of AA application using a shallow-depth AA applicator at multiple N rates were evaluated in no-till and conventional tillage systems. Intensive growth and development measurements were completed for bar-coded individual plants beginning with coleoptile emergence to maturity. Variation between individual plants in final ear weights were more strongly dependent on relative silk emergence of individual plants within the row than by the seedling emergence time or plant spacing. Some nitrogen (AA) system (rate, direction, and tillage) influences on the uniformity of individual corn plant growth and subsequent yields will be demonstrated.