Quick Tip

Most modern golf course putting green root zones are constructed using high sand contents, sometimes 90 percent or more by volume. Sand is an excellent rootzone material for heavily trafficked areas such as putting greens because it resists compaction and maintains air-filled porosity and drainage. Furthermore, it is a relatively inexpensive material and is readily available most anywhere.

Although sands provide favorable soil physical properties, nutrient retention is generally poor and water-soluble nutrients like nitrogen are prone to leaching.

Table 1

Young putting greens may receive 6 pounds to 8 pounds of actual nitrogen per 1,000 square feet annually, and applications of 10 pounds to 12 pounds during the first year of establishment are not uncommon.

Often nitrogen is supplied using highly soluble sources like ammonium sulfate or urea. Given all of the following conditions — porous rootzone media, water-soluble nitrogen applications, and regular irrigation — it is easy to see why nitrogen loss is a concern.

Table 2

It is well-documented that a dense mature turfgrass system, even on sandy soils, is very effective in capturing nitrogen because of its extensive root system. Although the potential for nitrogen leaching from mature turfgrass systems may be rather low, the same is not true for young turfgrass plants on newly built sand rootzones. In these situations, turfgrasses are either planted as seed or sod that is frequently irrigated because there is little or no root system to absorb water from the rootzone.

Light, frequent irrigation is required to ensure survival. Not only is the shallow root system unable to explore the rootzone for water, it is also less efficient at nitrogen absorption, which further increases the leaching potential.

Table 3

Historically, the most popular method for sand-based golf green construction has suggested amending sand with a stabilized organic matter, such as peat moss (USGA, 1993). This amendment is added to improve water and nutrient retention. In the past, many inorganic soil amendments, such as porous ceramics, diatomaceous earth and clinoptilolite zeolites, have been investigated and marketed as alternatives to peat moss (Davis et al., 1970; Waddington et al., 1974). These inorganic products may be better suited to sand rootzones because they are not susceptible to biological degradation and may sustain the original rootzone physical properties longer than peat moss.

Several researchers have documented the benefits of various porous ceramics and zeolites on turf establishment and growth when incorporated into sandy growing media. These results are not surprising since the base mineral for most porous ceramics is clay and many clays and zeolites have cation exchange capacities ranging from 50 centimoles of charge per kilogram (cmolc/kg) to 220 cmolc/kg compared to sand, which often is less than 1 cmolc/kg.