TechNotes Sept. 8 - Fall Fertilization, Soil Temperature

TechNotes are provided by Syngenta GreenCast.

Fall Nitrogen Fertilization Benefits All Cool-Season Turfs

All cool-season turfgrasses benefit from fall nitrogen (N) fertilization, regardless if it is a lawn, athletic field, or golf course green, tee or fairway. Normally fertilization should begin in mid-September and continue one or two more times until about mid-November. Starting the fertilization program in September will take advantage of favorable growing weather and encourage the production of new tillers and/or rhizomes and stolons that will increase turf density. These fall fertilizer applications also encourage rooting and production of storage products that will help the plant survive the stresses of winter and enhance growth for next year.  Although the summer of 2008 will probably be looked back upon as a relatively mild summer for most of the region, the past few weeks of heat and humidity have caused some turf areas to thin.  Thus, modest N applications are appropriate.

Probably the biggest choice regarding fertilization is what product and how much. In general higher cut (> 1.5 inches) should receive ¾ -1 lb of actual N/1000 sq ft using a fertilizer with 25-50 percent of the nitrogen as slow release (sulfur or polymer-coated urea, urea formaldehyde, or natural organics). Some of our recent research suggests higher N rates can be used with fertilizers containing even more slow release nitrogen, which may minimize the need for typical late October or November applications (the N in the Sept. application may release over 6-8 weeks or more). This would be very useful on low maintenance areas where labor is limiting. More fertilizer program information is available in AY-22: Fertilizing Home Lawns.

If you are confused on how much of a particular product to apply to achieve a particular N-rate, use this fertilizer calculator to help determine exactly how much product to use: . Additionally, with the volatile fertilizer prices being experienced by the industry this calculator may help you determine which products are most economical.

-Cale Bigelow, Assistant Professor of Turfgrass Science, Purdue University

Soil Temperature Map