With another summer golf season just about under our collective belts, it’s time again to consider our fall fertilization strategy. Some already have sure-fire programs established for their courses and have great success with them every year. To that I say, “Bravo!”
Others, like newer golf course superintendents or those in varying climates or dicey soil situations, find themselves needing to rewrite their fall fertilization textbook programs on a yearly basis based on these and other factors. A soil test by an independent laboratory is a good idea to help determine the needs of your turf heading into the fall and winter months.
Too much nitrogen can cause issues with snow mold and an unwanted flush of growth. Too little can leave plants weak and susceptible to winter injury and unable to come out of dormancy in the spring. Plants need the proper amount of nitrogen and other nutrients to help build and store carbohydrates for the cold winter ahead.
All about timing
Roots are the main avenues through which nutrients make it into turfgrass plants. Some schools of thought might argue that foliar applications are just as effective, but the leaves of the turfgrass plant already have their own function – to absorb light for photosynthesis and for transpiration to help prevent water loss.
Roots, on the other hand, are built specifically to absorb nutrients from the soil solution. Besides, in order to effectively make a foliar application, it requires a low water volume (less than 1 gallon per 1,000 square feet) in order for the droplets to remain on the foliage. Most of us are calibrated at much higher volumes, according to James Baird’s “Soil Fertility and Turfgrass Nutrition 101.”
In the fall, as the daytime temperatures are dropping, the soil temperatures are actually holding and are warmer than the air. Even though top growth may slow to a stop, roots are still functioning and absorbing nutrients.
This could be the best time to fertilize – when the plants aren’t producing top growth and are using the nutrients for carbohydrate production and storage. It depends on your fertilizer product.
What to apply when
If the long-range forecasts for your particular area are usually accurate, a slow-release, poly-coated fertilizer might be your best choice. With proper application timing, enough nitrogen can be released and available to the plant before dormancy occurs for carbohydrate production and winter storage.
When colder temperatures set in, nitrogen release stops until the soil warms in the spring, beginning the process all over again. The gamble with this school of thought is the hope that there isn’t a mid-winter thaw, which would allow the nitrogen to release too soon and be lost to leaching or runoff.
There is always the possibility of a warmer-than-usual spring and an earlier-than-expected release of nitrogen, resulting in a flush of growth and grass clippings you can’t keep up with.
Organic fertilizers can also be a good choice for fall feeding. Slow-release by nature, these fertilizers are also soil temperature-dependent, so timing is everything for this application in order to get nutrients into the plant before the onset of dormancy and still have enough leftover for a spring green-up. Be aware that this kind of fertilizer is also subject to leaching and runoff should you experience a cool, wet winter without a hard freeze.
What have you been taught?
“Lean and mean heading in to winter,” said one certified golf course superintendent, who is now retired after an illustrious career that included a transition-zone PGA Tour stop. “In my book, the perfect timing so the nitrogen is used in the right proportions heading into winter doesn’t exist,” he says. “Besides, snow mold thrives on nitrogen, so less is better.
“I prefer to have as little nitrogen available as possible heading in to dormancy – almost to the point of yellowing. The turf is actually heartier, and the snow mold has nothing to feed on,” he adds. “I prefer using soluble fertilizers and spoon feeding. This way I can observe and let the turf tell me what it needs without excess. It saves money in the long run on both fertilizer and chemicals.”
Realistically, no two seasons are the same, so sometimes you are faced with having to rewrite your schoolbook year to year to achieve your best results.