Submitted to: International Turfgrass Science Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/1/2005
Publication Date: 7/10/2005
Citation: Li, D., Minner, D.D., Christians, N.E., Logsdon, S.D. 2005. Evaluating the impact of variable root zone depth on the hydraulic properties of sand-based turf systems. International Turfgrass Science Journal. 10:1100-1107. Interpretive Summary: Constructed turf soil is a mixture of soil, sand, peat, and sometimes other potting mixtures. Sand increases drainage and stability, but results in droughty conditions. This study showed that adding 5% peat to the mixture increased the water retention of the constructed mixture, allowing more water to be available to the turf grass. Adding 15% peat to one of the mixtures resulted in water beading on the surface (water repellency) which decreased rewetting of the mixture and was detrimental to turf grass. The information is useful to golf green managers and to scientists who study constructed turf soil.
Technical Abstract: Root zone depth of golf greens will not only affect the cost of construction, but also the criteria of materials to be used. The objective of this study was to investigate the hydraulic properties as affected by root zone depth, sand particle size, organic amendments, and wetting directions. Two sand sources and three mixtures of the sands with reed sedge peat were tested in this study at seven soil depths, 10, 20, 30, 40, 50, 60, and 80 cm. Water content was monitored at 5-cm intervals of the soil profile and matric potential was measured at the soil surface after the root zones were saturated with water from the top and bottom, respectively. Based on matric potential measurements, capillary connections were broke at 40 cm tensions for Sand I and Sand II, respectively; whereas, mixing 5% (v/v) peat extended the breaking tensions of Sand I and Sand II to 50 and 56 cm, respectively. Adding 15% peat (v/v) to Sand II increased the breaking tension to 66 cm. The greatest water content difference due to wetting directions at same tension was 7% for the mixture of Sand I/5% peat. Total volume of water in the root zone integrated from the van Genuchten equation showed significant differences when the root zones were deeper than 20 cm. The results showed that both water availability and supply capacity are important for deciding the root zone depth.