In-Furrow Starter Fertilizers for Corn Production In Mississippi.

Ammonium polyphosphate (10-34-0) and Nachurs Alpine™ White Lightning (10-20-5-1S + 0.1Zn) have been evaluated as in-furrow starter fertilizers for corn at two locations in Mississippi in 2009 and 2010.  The two materials were evaluated at different nitrogen (N) rates based on location and production system.  The study was located at the Delta Research and Extension Center (DREC, Stoneville) with irrigation and at the North Mississippi Research and Extension (NMREC, Verona) under rain-fed conditions.   Nitrogen rates were 134 or 202 kg ha^-1 at NMREC and 202 or 269 kg ha^-1 at DREC.  The starter fertilizer materials were applied at rates of 23.4 and 46.8 liters ha^-1 (10-20-5-1S + 0.1Zn) and 46.8 liters ha^-1 (10-34-0).  While visual differences were evident early in the growing season at DREC there was no response to in-furrow starter fertilizers in either 2009 or 2010.  There was no significant response to N rates in 2009. However, a significant N rate response was measured in 2010.  Corn grain yield was substantially lower at the NMREC (7.8 to 10.4 Mg ha^-1) as compared to DREC (11.0 to 12.5 Mg ha^-1) both years of the study.  In 2009, at NMREC, there was a significant response to increasing N rates but no response to starter fertilizer.  In 2010, there was a response to 10-34-0 at the lower N rate but no response to starter fertilizer at the higher N rate.  Starter fertilizers continue to be evaluated and used by producers when early planting is considered and cool wet soil conditions are prevalent.  However, most research data suggest little need for the starters if soil test levels for phosphorus (P) are adequate.  When early-season deficiencies are evident, they are usually related to cool wet conditions.  The deficiency tends to disappear as soil temperatures improve.