In this study, we tested soil water reflectometers represented by the CS65x series soil water reflectometers. The objectives were to (a) quantify the sensing volume of the CS65x sensors, (b) evaluate common univariate and multivariate calibration models, and (c) assess the implications of using uncalibrated sensors. The support volume was determined by analyzing the response of the bulk dielectric permittivity to a changing amount of surrounding media in the radial and axial directions of the sensor. Calibration models were tested using a dataset of ∼300 soil samples spanning nine soil textural classes. A time series of rootzone soil water storage recorded in two contrasting soils and two intensive (n ∼300) spatial surveys of near-surface soil moisture were used to quantify the implications of using uncalibrated sensors. The electromagnetic signal of CS655 was concentrated within a ∼3.5-cm radius around the center of the sensor rods. Univariate and multivariate calibration equations reduced the mean absolute error (MAE) in soil moisture observations by ∼40% compared with factory default equations. Uncalibrated sensors did not change the pattern of soil moisture temporal dynamics but resulted in a strong bias in soil water storage in a silty clay loam soil and altered the soil moisture spatial patterns obtained in moderate to wet field conditions in a silty clay soil. The CS655 sensor with the Kargas and Soulis calibration equation (MAE = 0.026 cm 3 cm −3 ) appears to be an acceptable candidate for deployment in soil moisture monitoring networks seeking to avoid site-specific sensor calibrations.

Golf courses and sports fields with turfgrass surfaces have been moving toward sand-based root zone construction to enhance playability. Sand-capped systems are ideally suited for situations where poor water quality and/or clayey soils necessitate rapid drainage and the need to flush salts. This study evaluated sandcapping depth and subsoil texture on dynamics and availability of water as well as subsequent turf canopy and rooting characteristics. Objectives of this study were (a) to assess season-long turf performance and root distribution of 'Tifway' hybrid bermudagrass (Cynodon dactylon × C. transvaalensis Burt. Davy) turf established on various sand-cap depths (0-5 cm topdressed over 2 yr or 5, 10, or 20 cm) atop two subsoils (fine sandy loam or clay loam) and (b) to determine how sandcapping × subsoil combinations influence required irrigation frequency (1 vs. 2 d wk −1 at 0.6 × reference evapotranspiration) and soil moisture dynamics. Irrigation frequency had minimal effect on percent green cover during the entire study period. Root mass detected within the underlying 30-cm subsoil was inversely proportional to sand-cap depth. Turf performance during the study was primarily affected by capping depth and subsoil, suggesting that playing surfaces can be negatively affected if the wrong capping depth is chosen in the construction of sand-capped turfgrass systems. 1 INTRODUCTION Given growing demands on potable water resources, golf courses, sports fields, and municipal parks increasingly are being managed with low-quality reclaimed irrigation water (Cabrera, Wagner, & Wherley, 2013; Gelernter, Stowell, Johnson, Brown, & Beditz, 2015). Management of turfgrass in these areas can be challenging where the structure of fine-textured native soil has become degraded over time. Common problems associated with degraded

Turfgrass management relies on frequent watering events from natural precipitation or irrigation. However, most irrigation scheduling strategies in turfgrass ignore the magnitude of canopy interception. Interception is the process by which precipitation or irrigation water is intercepted by and evaporated from plant canopies or plant residue. The objective of this study was to quantify the magnitude of precipitation interception and throughfall in ‘Meyer’ zoysiagrass (Zoysia japonica L.) and ‘007’ creeping bentgrass (Agrostis stolonifera L.). We used a new method consisting of co-located pluviometers with and without circular turfgrass patches to measure interception and throughfall. The resulting dataset includes 15 storms and 25 individual rainfall events ranging in precipitation totals from 0.3 mm to 42.4 mm throughout the research study. Throughfall amount resulted in a strong (r = 0.98) positive linear relationship with precipitation totals. On average, zoysiagrass and creeping bentgrass canopies intercepted a minimum of 4.4 mm before throughfall occurred. This indicates that, on average, no precipitation reaches the soil surface for precipitation events <4.4 mm. After the point of throughfall, 16% of each additional millimeter of precipitation or irrigation is lost due to interception. Nearly, 45% of the area of the contiguous U.S. could result in >50% of the annual precipitation being intercepted by canopies of zoysiagrass and bentgrass. This study provides detailed insights to understanding the interception dynamics in turfgrass and highlights the inefficient nature of small precipitation and irrigation events in turfgrass systems.