“Diagnostic Core Analysis – A Powerful Maintenance Tool”

by Mike Mealman and Sam Ferro (Turf Diagnostics and Design, Inc.)

     Golf course superintendents and sports turf managers have access to a variety of diagnostic and maintenance tools.  One of the most descriptive, informative, and perhaps least utilized is the diagnostic core analysis.  Diagnostic cores allow for visual observations to be made, as well as, quantitative analysis of the constituents of a turfgrass system.  This type of testing is most often used to diagnose & make recommendations concerning problem greens or sports fields.  By providing a cross section of the turf system, the core acts as a window into the inner workings and make-up of the green or field.  This window provides information that can not be obtained from any other diagnostic technique.  Throughout this document we will refer to golf courses, golf greens, and sports fields.  For the purposes of this document, these terms are used interchangeably.

     When a turf manager is experiencing problems with drainage or turf growth, a diagnostic core analysis can often pinpoint the cause of these problems.  The results from the diagnostic core evaluation can be used to provide recommendations regarding the need for reconstruction or modification (removal of surface layers), or information regarding modification and verification of maintenance practices (topdressing, core aerification).  In addition, diagnostic cores analysis is used to obtain information for turf systems that are performing well.  This information can be used to guide routine maintenance practices, and as a baseline for comparison in the future.

    The ability to visually observe the current condition of the turf rootzone is what makes diagnostic cores one of the best forms of analyzing existing greens and fields.  As apparent in the photos (figure 1), problems such as layering (which disrupts water movement) are often evident once the core is cut open.  The formation of layers can be a result of contamination during construction, rootzone modification, sedimentation, and surface maintenance or the lack thereof.  Additionally, inconsistencies in rootzone depths, migration of sand into the gravel layer, and root growth problems and successes can also be identified

    Diagnostic core collection allows the turfgrass manager to obtain an undisturbed soil sample from a green or any other turf area.  The sample is taken in a method somewhat similar to cutting out a new hole on a golf green.  The core sample is collected using a piece of beveled PVC pipe, a hammer, and a 2x4 (figure 2).  Sample collection is achieved by driving the beveled end of the PVC pipe through the green profile until subgrade is penetrated.  When the sample is collected properly, the core serves as a cross section of the green from top to bottom.  After collection, the samples are then sent off to a qualified physical-testing laboratory for the diagnostic analysis. 

Figure 1:  Diagnostic Cores Collected from Two Golf Greens – The core on the left (A) shows layering of the top 2” of the green.  This layering indicates an insufficient core aerification program.  The core on the right (B) is from a renovated green where 12” of rootzone was placed over an existing green.

Figure 2:  Profile Core Collection

Diagnostic core analysis consists of documenting the physical characteristics of the green through accurate visual observations and laboratory testing.  Upon arrival at the lab, cores are cut open lengthwise and photographs taken.  Cores are then divided into observable layers for testing.  For undisturbed testing, two cores are sent into the lab per sampling area.  This allows for one core to be cut open for observations, etc., and one core to be used for undisturbed testing  Typically, organic matter content and particle size analysis is conducted on any layer with sufficient sample volume.  Performance testing (i.e. USGA physical analysis, water release characterization, and infiltration rate) can be conducted on larger layers, or composites of layers with similar particle sizes and organic matter contents, to quantify current field performance.  Undisturbed infiltration rate and bulk density testing can also be performed when multiple cores are submitted.

    Many golf course and sports fields use diagnostic core testing when making decisions concerning maintenance and renovation.  This procedure gives valuable insight in to the current condition of the turf system.  With proper analysis and recommendations, an owner and/or turf manager can make direct cost/benefit comparisons of various maintenance/reconstruction practices.  In addition this diagnostic procedure provides cost advantages over other testing methods.  The turf manager’s own crew can perform the simple sampling procedure, and you have the option of having the lab test a single problem green, compositing similar materials from several greens, or individually testing every green on the golf course.

Portions of this document were printed in the November 1999 issue of Golf Business Magazine.

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