Simulated traffic on turfgrasses during drought stress: II. Soil moisture, soil compaction, and rooting

Abstract

Turf is often subject to traffic stresses during drought. Our objectives were to evaluate the impacts of golf cart traffic applied during simulated drought on soil properties and turfgrass rooting. Soil and roots in the upper profile (0–30.5 cm) were evaluated in two cool‐season (C 3 ) [Kentucky bluegrass ( Poa pratensis L.) and perennial ryegrass ( Lolium perenne L.)] and two warm‐season (C 4 ) turfgrasses {buffalograss [ Buchloë dactyloides (Nutt.) Engelm.] and zoysiagrass ( Zoysia japonica Steud.)} maintained at golf course mowing heights (1.6 [fairway] and 6.3 cm [rough]) during a 41‐d drought (with traffic) and subsequent 40‐d recovery (without traffic). After drought, soil bulk density was ≤1.40 g cm −3 and generally below the 1.55 g cm −3 threshold, where root‐growth restriction is more problematic. After drought, soil penetration resistance exceeded 2.0 MPa at lower depths, especially at fairway height, which may impede root‐growth. The C 3 turfgrasses had 46–70% more root biomass and 150–290% more root length density than C 4 turfgrasses. However, only root diameter was correlated with turf canopy performance ( r  = 0.501; P  < .001), which was 20–23% less in Kentucky bluegrass; a smaller root diameter may have diminished its ability to explore for moisture as soils dried. Most differences in soil and root characteristics resulted from drought and not traffic stress, since the traffic main effect was not significant. Results indicate cart traffic during acute drought may have negligible effects on soil compaction and rooting. Decreasing soil moisture minimized the detrimental effects of traffic on soil compaction and rooting. Traffic during drought stress caused no change in gravimetric soil water content or soil bulk density. Rooting was influenced by species during drought, but not by traffic or mowing height.