Monday, January 22, 2018

Nitrogen and Topdressing

A solid 12 years of consistent data collection here at MGC has provided us an opportunity to look at a few trends.

One trend in particular that I am very interested in is the relationship between Sand Topdressing the putting surfaces and Nitrogen fertilization.  Sand topdressing the putting greens is a process we complete every 3-week throughout the golf season.  The goal of topdressing is to match the sand rate with turf growth so we can maintain a smooth firm putting surface for all to enjoy; establishing that rate is the art behind the science.  Daily turf growth is heavily influenced by our Nitrogen applications but is also dependent on climatic conditions (drought/rain/humidity/temperature), turf health and the use of Plant Growth Regulators (PGR’s).
I feel playing golf on your turf surfaces is the most important way to get an actual feel for how the ball reacts and rolls; we call that the playability.  Monitoring and recording clipping yield on the putting greens everyday is the next most important aspect to managing the surfaces properly.  Those data recordings coupled with playabilty help us dictate how much sand needs to be applied; it also helps make decisions on vertical mowing, depth of vertical mowing and if we need to brush the greens.    
Here at MGC we measure clipping yield by how many times the operator has to empty the collection baskets while mowing all 18 greens.  This measurement does fluctuate slightly between operators but the basic number is adequate for our needs.  Heavy flushes of growth can be observed in the spring or after Nitrogen applications, a soil temperature increase and after exhaustion of an applied PGR.  On the flip side growth reductions can also be observed after a reduction in air temperatures, a heavy frost, a drought condition or after a PGR application.
Our goal is always consistency with our turf growth so we try to eliminate any flushes by applying Nitrogen only when needed and only for normal plant growth so recovery from traffic can always be taking place.  We also apply PGR's based on growing degree models and we manage moisture on the dry side.  We triplex our putting surfaces; the goal is to maintain clipping yield at a rate that the operator is only emptying the baskets 1-2 times per 18 holes.  If the yield falls below 1 we typically roll or skip mowing the following day.  Growth rates higher than that level occurs during the spring growth flush (and explains slower green speeds at that time) but is avoided during the rest of the season by our management techniques.  

In these numbers you can easily see the reduction in Granular fertilization over the years.  Purchasing a large area sprayer in 2015 was a game changer as it allowed us to extend our foliar Nitrogen applications from the greens to all fine turf surfaces; fairways, approaches, tees.  Nitrogen can now be applied at a much lower rate giving us better growth control.

Our total Nitrogen use has reduced over the years but our turfgrass quality has increased.  More effective and efficient use with less waste and virtually no flushes like we experienced 10 years ago.

**For the last 3 seasons our only complete granular application on the greens has been our dormant Milorganite application.  High applications rates of Milorganite at this time decreases the time it takes for snow/ice to melt in the spring and jumps starts the turf immediately when exposed.  I do estimate that 1/2 of that Milorganite application is removed in the spring when we brush reel, vertically mow and mow for the first time in the spring.  The collection baskets are full of Milorganite so we recycle that fertilizer by spreading it on cart path wear areas around the two courses.**

A chart/graph again showing our change in application methods over the years and our reduction in overall use of fertilizer.

Looking at this graph helps summarize why we had more flushes of growth from 2006-2012.  Granular fertilization can give very unpredictable results with varying climatic conditions. 

How does Nitrogen relate to Sand Topdressing?
In-season sand use has decreased over the years but post-season (winter crown protection) use has increased so our over all sand topdressing has remained relatively flat over the last 11 seasons but I would like to just focus on in-season use.
In-season use is dependent on monitored clipping yield and playability so it truly reflects our ability to control flushes of growth.  In 2008/09/10 we made our highest Nitrogen applications to the greens so we indeed had more growth; which is directly reflected with an increased in-season sand use over that time period on both golf courses.  During those years we routinely set our topdresser gate at setting C to get the proper amount of sand into the canopy.  We now have such controlled growth we have no need to open the gate past the first A setting yet still get better results.
Along with reduced in-season sand use we have been able to reduce vertical mowing depth.  11 years ago (when we did not have as much control over growth rates) surfaces felt soft to me after 3 weeks so it was necessary to complete vertical mowing to a depth deeper than neutral to 'mine' out Organic Matter (OM) and add sand to the channels.  With successful controlled growth rates in resent years, surfaces stay firmer and vertical mowing does not regularly need to be completed as deep.

Heritage and Greywalls In-season sand use has trended down and has stabilized the last two seasons.  Sand use was a little low in 2012/2103/2014 but corrections were made.
I really like where we are with our putting surface management.  We are more consistent than we have ever been.

This summarizes the total sand depth that has been added to the putting surfaces through our regular topdressing over the last 11 seasons.

Management improvements over the last 12 years have had a tremendous impact on our ability to consistently manage our most important turf surfaces.  There is no text book telling you how much and how often; it is all site specific and based on experience, inputs, available equipment, time limitations and expectations.  We are always focusing on getting better and providing a better product to play on.... our efforts are working.

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