Localized Dry Spots as Caused by Hydrophobic Sands on Bentgrass Greens

Abstract

Construction of creeping bentgrass (Agrostis palustris Huds.) golf greens with topsoil mixtures that contain 90% or more sand has led to the appearance of irregularly shaped areas of wilted or dead turfgrass known as localized dry spots (LDS). Objectives were to determine by means of a survey the association between management practices and the severity of LDS, and to compare the chemical and physical properties of LDS and adjacent healthy areas (HA) of greens. Turf managers from ten golf courses and the University of Georgia Turfgrass Plots completed a 34-question survey pertaining to management practices used on their respective greens. Four of the golf courses and the University Turf Plots were selected as sampling sites for soil from both LDS and HA. Soil was analyzed for moisture content, and particle size, as well as hydrophobicity via the water droplet penetration time, and contact angle methods. Soil organic matter, soluble salts, pH, P, K, Ca, Mg, Zn, Mn, B, and NO,, were also determined. In addition, soil from each area was viewed with a scanning electron microscope. Dry spots occurred at all locations surveyed and no correlation was observed between management practices and the severity of LDS. No differences in soil chemical properties were found between LDS and HA, but water droplet penetration time and contact angle were greater in LDS compared to HA. This hydrophobic condition was confined to the top 50 mm of soil in the dry spot samples and coincided with the presence of an organic coating on sand grains that was observed by scanning electron microscopy.

Influence of humic acid on water retention and nutrient acquisition in simulated golf putting greens

“…, 2005). Hydrophobic soil is particularly found in the upper 5 cm of the profile (Tucker et al. , 1990) and, although preferential flow was not measured in our study, preferential flow patterns or fingering (Bauters et al.…”

Soil surfactant stops water repellency and preferential flow paths

“…Although water repellency in a soil has several possible origins, numerous researchers agree that it is caused by a hydrophobic organic coating on the soil particles (Tucker et al, 1990;Hallett et al, 2001). This coating does not necessarily cover the soil particles completely nor is it necessarily very thick.…”

Water Repellency Varies with Depth and Season in Sandy Rootzones Treated With Ten Wetting Agents

“…Inhibited turf growth, increased run‐off, uneven wetting patterns, preferential flow, and accelerated leaching of applied fertilizers and chemicals are all a result of hydrophobic soil conditions (17). Soil repellency can be attributed to hydrophobic compounds present either in the soil as interstitial matter or on soil mineral or aggregate surfaces (9,10,26). The hydrophobic organic compounds are released from roots (6,8), fungal or microbial by‐products (13,24), or can be produced directly by decomposing organic matter (20).…”