Fall Formula for Fertilization

Hard to believe it’s that time of year again. Time to start planning for fall and eventually putting the course to bed.

It wasn’t that long ago that we were (at least, I was) carefully watching our courses as they came out of winter dormancy and planning for the first spring fertilizer application. The goal was to get the plants healthy and hardy heading into summer, making them as strong as possible to help fight off the summer stresses of heat and high traffic.

But now, as the number of daylight hours decrease and nights get cooler, plant top growth slows and will eventually come to a halt. However, that doesn’t mean the plants aren’t functioning anymore. Soil temperatures won’t drop as quickly as air temperatures, so roots are still active and taking up available nitrogen and other nutrients to help build and store carbohydrates. These carbs help plants fight off winter stress injury, and encourage new root growth and green-up the following spring.

This is also a good time to increase mowing heights for optimal photosynthesis and the resulting beneficial carbohydrate production.

Here’s where the balancing act begins. We need to provide turf with the nitrogen (N) it needs for optimum fall/winter/spring health, but we don’t want to waste time and money by applying products that will either leach out or run off before the plant can take advantage of your efforts.

The unofficial turf whisperer formula varies on your location, facility and budget, but the goal is the same: providing enough available N for turf to create the storage it needs to make it through the winter, with enough available N left over to wake turf up the following spring.

What to use

At first glance, slow-release forms of N seem to be the obvious choice, but you have to apply these products when soil temperatures are warm enough and water is available so some N can be released to the plant before cold temps and dormancy set in. An application too late in the fall could spell trouble for turf if it can’t store the carbs it needs – the turf may suffer some winter injury if it hardens off beforehand because of lack of available N (and/or potassium, a must for winter hardiness).

The beauty of poly-coated fertilizer is that the release of N is metered out based on soil temperatures. Once the cold sets in for the winter, the N is no longer released and the fertilizer goes dormant, along with the turf, waiting for the warmer weather of spring to begin releasing N again. Spring green-up begins exactly when the plants are ready as the soil begins warming up.

Again, be sure to put poly-coated fertilizer down early enough so some N is available before full dormancy.

Natural organic fertilizers can also help provide that early spring green-up we love to see, but there are no guarantees it will be available if your area experienced a cold, wet winter and most of the N is lost to runoff.

Conversely, while a readily available N fertilizer source may provide the food needed for carbohydrate production, what isn’t taken up by the roots will simply leach out through the soil profile and be wasted.

Some schools of thought suggest a fall foliar application to help push root growth and carbohydrate storage, but again this leaves nothing behind for spring, and may cause a flush of growth with a late surge of warm weather.

Some agronomists also warn that providing too much N will necessitate more fungicide applications to protect against snow mold, so you have to be vigilant about the amount of N applied throughout the year.

Obviously, the product you apply will vary depending on when you plan to apply it, what your overall annual fertilizer program consists of, and what your budget will allow. Hopefully, your turf management goals mirror those of the club owners and optimum turf health is top of the list.

One of the hardest obstacles we face as superintendents is the inability for some players and/or club operators to understand the agronomic side of our efforts, and the fact that many of the things we do are for the long-term benefit of the grass on our golf courses.

While a big fertilizer purchase heading into late fall/winter may seem like a huge expense as round counts are dropping, it will pay for itself the following spring when your course looks great and the tee sheets are filling up again.