AGRI-BRIEFS
  AGRONOMIC NEWS ITEMS
From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335

Spring 1999, No. 7

DON'T OVERLOOK THE POTENTIAL OF STARTER THIS SPRING

The benefits of starter fertilizer have been recognized for many years. Phosphorus and other nutrients placed in a concentrated band near the seed at planting often result in early season response that translates to yield increases and greater profit in corn and grain sorghum production. Some of the potential benefits of starter include: Several factors affect response to starter fertilizer. Soil conditions that increase the likelihood of starter response include cool soil temperature at planting and root growth restrictions such as soil compaction, soil acidity, soil salinity, and herbicide carryover. The need for starter phosphorus is expected to decrease as soil test levels increase. However, other factors like soil temperature or drainage may override the effect of soil test level. In other words, the use of starter may be profitable where early cool, moist soil conditions prevail, even though soil test phophorus level is high.

Another important factor in considering the potential of starter fertilizer is residue level and degree of tillage. High levels of residue increase the potential of a profitable response to starter due to prolonged cool, wet spring soil conditions. Also, with reduced tillage, stratification of immobile nutrients such as phosphorus and potassium is increased, resulting in a greater potential for response to subsurface banding.

In a recent three-year Kansas study, starter application of 30 pounds of nitrogen and 30 pounds of P2O5 per acre in a 2x2 placement (2 inches to the side and 2 inches below the seed) in a high residue, no-tillage system resulted in yield increases in seven of 12 corn hybrids and eight of 12 sorghum hybrids even though soil test phosphorus levels were very high. The three-year average responses were 17 bushels of corn per acre and 15 bushels of sorghum per acre. In addition, grain moisture at harvest was consistently reduced and maturity hastened by the starter in the responsive hybrids. The nitrogen:P2O5 ratio of 1:1 was selected in this study because of its superior performance in an earlier study where in no-till grain sorghum a starter application of 30 pounds of nitrogen and 30 pounds of P2O5 per acre out-yielded the control and the 10 pounds of nitrogen, 30 pounds P2O5 per acre starter application.

When starter is applied in a 2x2 placement the chance of injury and stand reduction from salt damage is negligible. However, where fertilizer is applied in-furrow with the seed, care should be taken to avoid seedling injury, stand reduction, and yield loss. The amount of fertilizer that can be used depends on fertilizer source, crop, row width, and soil moisture. For example, South Dakota State University recommends for corn in 30 inch rows no more than 10 pounds of nitrogen plus K2O, up to 100 pounds per acre of material as 0-46-0, and no urea or urea/ammonium nitrate combination.

The use of starter fertilizer is an effective management practice that is based on sound agronomic principles. So, don’t overlook the potential benefits of starter this spring.


—WMS—

For more information, contact Dr. W.M. (Mike) Stewart, Great Plains Director, PPI, P.O. Box 6827, Lubbock, TX 79493. Phone: (806) 795-3252. E-mail: mstewart@ppi-far.org.
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