Saturated Hydraulic Conductivity of Sand-Based Golf Putting Green Root Zones Affected by Sodium

Sodium hazard recommendations are primarily based on research conducted on fine-textured soils with moderate to high clay contents. However, sand-based golf putting greens typically contain very little clay (<3% by weight), and there is little evidence to suggest that sodium negatively affects saturated hydraulic conductivity (K-sat) of sand-based root zones with a low clay content. This study was designed to evaluate the effects of sodium on sand-based putting green soils. Putting green root zones were constructed with various amendments and saturated in solutions to create a range of base cation saturations. Saturated hydraulic conductivity was measured and compared with exchangeable sodium percentage (ESP) on soil cation exchange sites. In five of six root zone mixes, increasing ESP did not affect K-sat; only an 80: 20 mixture by volume of sand/loam containing 4.8% clay had significantly lower K-sat as ESP increased to 25%. These findings suggest that current sodium hazard recommendations should be adjusted to account for soils with a low clay content. However, this research did not evaluate the effect of sodium on unsaturated flow or the effect of localized areas of a high clay content (clay lenses). The clay in this study was uniformly distributed through the profiles, and future work should evaluate clay accumulation at depth in these soils. The concept of soil plasticity is proposed as a quantitative assessment of sodium hazard, where only soils that exhibit plastic properties would be negatively affected by sodium.