Aeration and Topdressing for the 21st Century - USGA Green ...

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Seeing is believing withvolumetricmeasurements.Light, medium,and heavy surfacetopdressingratesare approximately0.50 ft! per 1,000 ft?-,2.0 ft! per 1,000 ft?-, and4.0 ft! per 1,000 ft?-,respectively.profile. Spring and fall dethatching treatments areperformed. Less disruption to play is the primaryadvantage. This program is not recommended as acurative approach on greens with excessiveorganic matter. It is too difficult to incorporatesand into the channels made by the dethatchingequipment, especially when the grooves are cutgreater than 0.25 in. deep.The amount of sand incorporated into thecanopy following dethatching is much lower thanwith core aeration. As channel depth increases,sand incorporation decreases because the channelscollapse and seal off. This may be considered adisadvantage because much more time must bespent applying light and moderate topdressingsthroughout the year. For example, assumethe greens are dethatched with %4 in. blades.Approximately 14% of the surface area isimpacted, but only 1-3 ft? per 1,000 fe of sandis applied. This amount is highly variable anddepends on how well the dethatching channelsstay open. This leaves 40-44 ft? per 1,000 fe leftto be applied throughtopdressings .light and moderateMany courses that use a dethatching machineuse it in combination with an aerator. Somedethatch and aerate at the same time, while othersde thatch and aerate on separate dates.The moderate topdressings (2.0 ft? per 1,000ft?) should be applied at a time of year whenorganic accumulation is most rapid. On bentgrassputting greens in the South, the period ofOctober through April is the most prolific periodof organic matter production. Bermudagrassgreens generate the most organic matter in thesummer months. Light topdressings can beapplied at any time of the year.• Small Holes, Small Spacing. A sampleprogram using this approach might include thefollowing: super quad tines with an outside tinediameter of 0.420 on a 1 in. X 1Ysin. spacing. Thegreens are aerated twice in the spring and once ortwice in the fall. The total amount of sandrequired to fill the holes after each aeration isapproximately 6.15 ft? per 1,000 fe or 18-24 ft?per 1,000 fe per year. The remaining16-32 ft?per 1,000 fe can be applied through light ormoderate topdressings throughout the year.This approach relies on smaller tine diametersand a tighter spacing pattern. The advantage ofthis program is reduced healing time becausesmaller diameter holes require less time to healthan larger holes. The disadvantages are the needfor special equipment and more difficulty fillingthe aeration holes. As hole size decreases, the likelihoodof sand particles bridging over the surfaceof the hole increases. The super quad tine onlygoes 1.75 in. into the rootzone, which could be aconcern with a thick layer of organic accumulation.An aerator with variable spacing and a tractorwith a creeper gear are necessary to duplicate thisprogram. For best results, take the time to makesure the holes are open and clean, and try to usethe driest sand possible.4 GREEN SECTION RECORD
THEORYVS. REALITY:CALCULATING SAND VOLUMEEvery golf course is faced with a unique set ofcircumstances. Determining the total amount oftopdressing applied can be challenging. Table 2shows the approximate amount of sand necessaryto fill aeration holes with sand for common tinesizes and spacing.When recommended topdressing amounts arein hand, the turf grass manager must adjust thetopdressing applied if it is determined that thesand is not working easily into the holes. Sometimesthe greens are damp or the sand is wet. Thedegree to whichsand is filled into the holes canvary, too. The key point is not whether the suggestedamount is applied to fill the holes, but howmuch sand actually is applied. This information ishelpful when calculating yearly volume and determininghow much sand must be added throughlight or moderate topdressing applications.When calculating sand volume applied, anotherconsideration is estimating how much sand isthrown onto areas other than the putting green.This is an issue when spinner top dressers are usedto apply light or moderatetopdressings.MEETING THE RECOMMENDATION:IS MORE OR LESSNEEDED?The beauty of coupling aeration and topdressingtogether and making an annual topdressingrecommendation as a target value is its simplicityand flexibility. It may need to be adjusted upwardor downward, depending on individual circumstances.The Atlanta, Georgia, climate was selectedfor this recommendation. Other areas may requirea higher topdressing or lower requirement basedupon some of the factors listed below.• Nitrogen Levels. Nitrogen is directly relatedto organic matter production. Higher nitrogenprograms may be required on putting greens withextremely high traffic levels or on greens thatmust be grownin from some type of seasonaldamage. More topdressing may be required.Greens managed under low nitrogen programsmay require somewhat less sand .• Soil pH. A soil pH > 5.5 is optimal forbacterial activity and organic matter decomposition.Soil pH much below this level reducesorganic matter decomposition, and more topdressingmay be required.• Turfgrass Species. The 40-50 ft? per 1,000fe recommendation is the minimum requirementfor many bentgrass and/or Paa annua puttinggreens and may need to be adjusted annually.N on-overseeded Tifdwarf or Tifgreen bermudagrassputting greens will have a slightly lowerannual topdressing requirement, somewhere inthe range of35-40 ft? per 1,000 ft? Non-overseededultradwarfgreens may require 40-50 ft?per 1,000 ft? Overseeded Tifdwarf or Tifgreenbermudagrass putting greens will require 40-50ft? per 1,000 ft?, but with newer ultradwarfcultivars that tend to accumulate organic matterin the surface 1-2 in., a somewhat higher amountmay be necessary. For newer bermudagrass cultivars,the "small holes, small spacing" programapplied at more than two times per year is a goodoption. High annual topdressing sand rates areimportant for the newer bentgrass cultivars thattend to accumulate organic matter in the surfaceor in climates where organic matter accumulationis favored. In these situations, the "small holes,small spacing" program is worth trying.UNUSUAL FIELD CONDITIONSTwo common field conditions exist that mayrequire a higher sand requirement or an adjustmentas to when sand should be applied.• Rapid Root Dieback. This condition ischaracterized by the rapid death of a bentgrassroot system caused by high temperatures in thesummer months. When bentgrass roots die backsuddenly, the nature of some of the organic matterOrganic matteraccumulation in theupper rootzone is theprimary reason whyputting greens sometimesfail over time.Proper aeration andtopdressing programscan prevent excessorganic matteraccumulation.MARCH-APRIL 2003 5
Page 1 and 2: BY PAT O'BRIEN and CHRIS HARrWlGER~
Page 3: many questions that will be address

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