Development of a USGA Putting Green Rootzone Mixture (Greensmix)

This is the test where we determine if the sand you have selected meets USGA particle size recommendations for a greensmix.  If it does, we mix the sand with 10, 15, and 20% peat to develop the mix design that meets USGA physical property recommendations for saturated hydraulic conductivity (perk rate) and porosity.  Included with the recommended mix is an organic matter test so that field mixes can be referenced back to the recommended lab mix and pH and lime recommendations.  Sometimes the mix design will include soil or an inorganic amendment.

Complete Rootzone Analysis

This test includes a complete physical and particle size analysis of a greensmix sample including organic matter, pH and lime recommendations, and USGA recommendations for a putting green rootzone mixture (greensmix).  This is the deluxe quality control test of a greensmix and tests for all the physical quality properties considered important by the USGA for a greensmix.

Complete Physical Analysis

This test includes the saturated hydraulic conductivity (perk test), pore space distribution (porosity), bulk density, particle density, and water retention.  This test assesses the physical properties of a rootzone mix to see if they meet USGA recommendations.  Ideal physical properties of a green promotes good turfgrass growth and optimum playability. This test is often used as a quality control test for a greensmix.

Complete Particle Size Analysis

This test determines if the sand/rootzone mix meets USGA particle size recommendations for a rootzone mix.  The particle size analysis consist of the percentage of gravel, sand, silt, and clay including the five sand fractions.  Sands that are too coarse or too fine will not pass USGA particle size recommendations.  Greens built with sands that are too coarse are too loose, difficult to firm up, droughty, and difficult to retain fertilizer nutrients due to excessive leaching. Greens built with sands that are too fine become hard, compacted greens with low water permeability rates.

Organic Matter Test of Rootzone Mix

This test determines the organic matter in a rootzone mix, usually for golf greens. The USGA no longer recommends a value for the organic matter in a greensmix, however this test is primarly used as a quality control test to determine if the organic matter established in the mix design is close to the organic matter in on-site field mixes.

Organic Matter Test of Peat and Other Organic Soils

The USGA recommends that the peat used in a greensmix should have a minimum of 85% organic matter content by weight and should be screened to no larger than 0.25 inches (6.4 mm).  Organic composts, if used, should meet the requirements found in "USGA Recommendations for a Method of Putting Green Construction," and the mix must meet physical property recommendations.  The organic matter plays an important role in the physical quality of a greensmix.

Gravel Particle Size Analysis

The USGA recommends two methods for golf green construction, with and without an intermediate (choker) layer.  When the intermediate (choker) layer is used, a 4" layer of 1/4 X 3/8" (6.3 X 9.5mm) gravel (65% minimum) is placed above the drain tile.  A 2-4" layer of 1-4mm intermediate layer (90% minimum) is placed above the gravel. The 12" rootzone mix is placed above the intermediate layer.

When the intermediate layer is not used, a minimum 4" layer of 1/4 X 1/8" (6.3 X 3.2mm) gravel is placed above the drain tile.  The 12" rootzone mix is placed above the gravel.  The gravel has to pass bridging and permeability factors with the sand and a uniformity factor.  The gravel particle size test determines if the gravel used for these two methods passes USGA requirements which are based on adequate drainage and prevention of rootzone particle migrating into the gravel.

Topdressing Sand/Greensmix Test

This test includes a physical and particle size analysis including pH and USGA recommendations for a topdressing sand.  If the topdressing is a sand:peat mix we also run an organic matter test.  The USGA recommended range for a topdressing sand is 1.0-0.15mm.  The USGA has recognized for many years that the medium sand fraction is the best sand fraction for a topdressing sand.

Bunker (Trap) Sand Test

The USGA recommends seven factors when selecting a bunker sand.  They are particle size; particle shape and penetrometer value; crusting potential; chemical reaction (pH) and hardness; infiltration rate (>20in/hr.); color; and playability.  This is our complete bunker sand test.  These tests predict the overall playing quality and maintenance of a bunker sand.

Chemical Analysis

Our lab also provides soil fertility analysis with fertilizer recommendations and pH and lime recommendations for bermudagrass and bentgrass greens, warm season grasses and cool season grasses for fairways and tees, athletic fields, and lawns.  Other chemical analyses include soluble salts and cation exchange capacity.