Evaluation of microlysimeters used in turfgrass evapotranspiration studies with the dual-probe heat-pulse technique

Microlysimeters (ML) are commonly used in turfgrass evapotranspiration (ET) studies. No standard exists for ML which has resulted in multiple designs that may affect soil moisture. The effects of ML design on volumetric soil water content ([Greek letter theta subscript v]) were investigated using the dual-probe heat-pulse (DPHP) technique. DPHP sensors were installed at 5, 15, and 25 cm in the ambient soil profile and in 3 designs of ML: 1) 15 cm diam. x 30 cm, mesh base, soil fill (MSL); 2) 15 cm diam. x 30 cm, plexiglass base (one drainage hole), soil fill (PSL); 3) 10 cm diam. x 20 cm, mesh base, soil (intact cores) (MSNL). Sleeves and a 5 cm layer of gravel were placed in MSL and PSL. DPHP estimates of [Greek letter theta subscript v] revealed that soils consistently dried faster in MSL and PSL than in the ambient profile, probably because of higher LAI and biomass in MSL and PSL than in surrounding turf, limitations of roots to extract soil water only from ML, and evaporation through open bases. In MSNL, [Greek letter theta subscript v] was similar to but may have been in hydraulic contact with ambient soils. Correlation was good between [Greek letter theta subscript v] determined by DPHP and by gravimetric methods; DPHP sensors on average (all ML) measured [Greek letter theta subscript v] to within 0.025 m[superscript 3] m[superscript minus 3] of gravimetric estimates. ET estimates varied significantly among ML and were strongly correlated to LAI and aboveground biomass (r=0.85). Results suggest that establishment/maintenance of similar LAI and biomass between ML and surrounding turf may be more important than ML design in providing accurate ET estimates, and bases should be sealed during ET measurements to prevent hydraulic contact with soil, drainage, or evaporation through bases

Growth Responses of Zoysia spp. under Tree Shade in the Midwestern United States

‘Meyer’ zoysiagrass (Zoysia japonica Steudel) is commonly planted on home lawns and golf courses in the transition zone; however, poor shade tolerance limits its widespread use. This study was conducted to determine changes and differences in growth among selected Zoysia cultivars and progeny under a natural shade environment over a 3-year period in the transition zone. The study was initiated in June 2010 at the Rocky Ford Turfgrass Research Center in Manhattan, KS. Soil type was a Chase silt loam (fine, montmorillonitic, mesic, Aquic, Argiudoll). Zoysia genotypes were sodded in 0.37-m2 plots and arranged in a randomized complete block with five replications under silver maple (Acer saccharinum L.) shade that resulted in a 91% reduction in photosynthetically active radiation (PAR). Genotypes included ‘Zorro’ [Z. matrella (L.) Merrill], ‘Emerald’ [Z. japonica × Z. pacifica (Goudswaard) Hotta & Kuroki], ‘Meyer’, Chinese Common (Z. japonica), and experimental progeny Exp1 (Z. matrella × Z. japonica), and Exp2 and Exp3 [(Z. japonica × Z. pacifica) × Z. japonica]. ‘Zorro’ and ‘Emerald’ experienced winter injury, which negatively affected their performance. Tiller numbers decreased 47% in ‘Meyer’ from June 2010 to June 2012, but declines in [(Z. japonica × Z. pacifica) × Z. japonica] progeny were only 1% for Exp2 and 27% for Exp3, and both Exp2 and Exp3 maintained high percent green cover throughout the study. In general, by the third year of evaluation, progeny of [(Z. japonica × Z. pacifica) × Z. japonica] had higher quality ratings and higher tiller numbers than ‘Meyer’ and may provide more shade-tolerant cultivar choices for transition zone turf managers

Lawn-watering perceptions and behaviors of residential homeowners in three Kansas (USA) cities: implications for water quantity and quality

Urbanization is increasing the land area covered with turfgrasses, which may have implications for water quantity and quality. The largest sector of turfgrass is residential lawns. Our objectives were to survey residential homeowners in three Kansas cities about their perceptions, knowledge, and behaviors when irrigating their lawns; each city has distinctive water quantity and quality issues. Surveys were mailed to 15,500 homeowners in Wichita, 10,000 in Olathe, and 5,000 in Salina; the return rate was 11-13%. Wichita residents watered more frequently than Olathe and Salina, possibly because of greater evaporative demand than Olathe, and cheaper water and less concern about water shortages than Salina; Salina and Wichita have similar evaporative demands but Salina had a recent water crisis. Salina homeowners were most concerned about keeping their water bill from getting too high, probably because of higher water costs than the other cities. Overall, 45-60% indicated it was moderately to very important their lawns looked green all the time, while 65-77% ranked water conservation at the same level of importance. Significantly, 61-63% did not know how much water their lawns required and 71-77% did not know how much water they applied to their lawns when they irrigated. About 7-9% swept or blew clippings or lawn-care products directly into streets or storm drains, which run directly into local streams or reservoirs; 9% in Wichita is ~9,000 homeowners. The homeowner’s lawn irrigation knowledge and habits must be improved to help conserve water and protect water quality

High and Low Management Input Regimes Result in Similar Net Carbon Sequestration Rates in Zoysiagrass Golf Course Fairway Turf

This study was conducted from 2013–2016 to determine how irrigation and N fertilization may be managed to enhance carbon (C) sequestration in turf. In this study, the annual rate of change in soil organic carbon (ΔSOC) was measured under two management regimes, a high management input regime (HMI) and low man­agement input regime (LMI), in a ‘Meyer’ zoysiagrass (Zoysia japonica Steud.) golf course fairway. Both management regimes maintained acceptable turf quality and at least 75% green cover during both summers. In both management regimes, soil organic carbon (SOC) increased after the 3.16-yr (1154-d) period indicating that C was sequestered in the soil. The C emissions from turfgrass maintenance prac­tices (mowing, irrigation, and fertilization and pesticide applications) are known as “hidden carbon costs” (HCC). The average gross C sequestration rates for the two treatments were not statistically different at 1046 kg C/ha/yr and 976 kg C/ha/yr in HMI and LMI, respectively, prior to subtracting HCC. Once the total estimated HCC was included, the average net sequestration rate was 412 kg C/ha/yr and 616 kg C/ha/yr in HMI and LMI, respectively, with no statistical differences. Our study indicates high and low management input regimes result in similar net C sequestra­tion rates in zoysiagrass golf course fairway turf

Considerations with using unmanned aircraft systems in turfgrass

In recent years, small unmanned aircraft systems (sUAS) and advancements in remote sensing technology have provided alternative and more affordable means for monitoring crop health and stress than ground-based (hand-held or vehicle-mounted) or other aerial-based platforms (manned aircraft or satellites). However, few scientific studies have evaluated the application of sUAS in turfgrass systems. The use of sUAS in monitoring turfgrass requires an understanding of basic remote sensing principles; identifying the target of interest and the various sUAS platforms and sensors that provide the necessary resolution and frequencies to measure and monitor that target; calibration of sensors in the field; and data processing considerations. Those topics are discussed, followed by reviews of recent turfgrass field studies conducted to predict and manage drought stress and pest outbreaks, and improve phenotyping capabilities in turfgrass breeding programs. The use of sUAS remote sensing in turfgrass offers unique possibilities and challenges, which are addressed herein

Thermal Imaging Detects Early Drought Stress in Turfgrass Utilizing Small Unmanned Aircraft Systems

Plots of fairway-height creeping bentgrass were watered differently to create a gradient of drought stress from severe deficit irrigation to well-watered, under an automatic rainout shelter in Manhattan, KS. Canopy temperature (Tc) measured by a small unmanned aerial system (sUAS) predicted drought stress approximately 5 days or more before drought symptoms were evident in either turfgrass visual quality (VQ) or percentage green cover (PGC). The ability of Tc to predict drought stress was comparable to the best spectral parameters acquired by sUAS on companion flights [i.e., near infrared (NIR) and GreenBlue VI], and slightly better than with spectral data obtained from handheld sensors. Better drought-prediction ability combined with faster data collection using sUAS indicates significant potential for sUAS-based compared with ground-based drought stress monitoring methods

Simulation of Nitrous Oxide Emissions in Zoysia Turfgrass Using DAYCENT and DNDC Ecosystem Models

Nitrous oxide (N2O) is an important greenhouse gas (GHG) implicated in global climate change. Process-based ecosystem models, such as DAYCENT and DNDC, have been widely used to predict GHG fluxes in agricultural systems. However, neither model has yet been applied to warm-season turfgrasses such as zoysiagrass. This study parameterized, calibrated, and validated the DAYCENT and DNDC models for N2O emissions from Meyer zoysiagrass (Zoysia japonica Steud.) using Bayes’ theorem and field data from Braun and Bremer (2018a, 2019) and Lewis and Bremer (2013). Results indicated DAYCENT, but not DNDC, reasonably simulated the impacts of irrigation and N-fertilization practices on biweekly and annual N2O emissions in zoysia turfgrass. When assuming no further climate change, the validated DAYCENT model predicted that typical recommendations for N-fertilization and irrigation in zoysiagrass (a low-input turfgrass) would reduce its cumulative global warming potential (GWP) for the first 45 years after establishment by encouraging soil carbon sequestration. Thereafter, soils would become saturated with carbon and hence, reductions of N inputs would be beneficial for mitigating further increases in N2O emissions and GWP

Urban Lawn Microclimates Affect Reference Evapotranspiration

Grass reference evapotranspiration (ETo) obtained from weather stations in open locations is often used to estimate irrigation requirements of turfgrass in local or regional urban lawns. However, the environments of urban lawns are often altered by surrounding buildings, trees, etc., to form various microclimates that may alter evapotranspiration (ET). Our research, which placed weather stations in urban lawns and nearby open swards of turfgrass, revealed ETo was 41% lower in residential lawn microclimates than in nearby open turfgrass swards. Less ET within urban lawns than in nearby open swards suggests using standard historical weather data to estimate irrigation amounts in urban lawns (based on ETo) is problematic, because historical weather data is typically obtained from open areas such as local airports (Ley et al., 1996; Romero and Dukes, 2013). Consequently, the use of weather stations located onsite, or at least in an urban lawn within the same region, may improve estimates of lawn irrigation requirements

Establishing Seeded Tall Fescue with Covers and Drip Irrigation Methods

The use of covers may improve establishment of seeded turfgrass but their use in combination with drip irrigation techniques has not been evaluated. We investigated the effects of two cover types and three irrigation methods on establishment of seeded tall fescue turfgrass. For spring seeding of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.], turf establishment was successful with subsurface drip irrigation (SDI) and aboveground drip irrigation (AGD) in fine textured soil in the transition zone. With SDI, AGD, or sprinkler irrigation, both polyester mesh (Poly) and straw blanket (Straw) covers improved turf establishment in the order of Poly \u3e Straw \u3e No Cover, but turf establishment in Poly and Straw became similar over time. Soil surface temperature averaged higher in Poly (14°C [57°F]) than Straw (9.5°C [49°F]) and No Cover (8.6°C [47.5°F]) during the first 12 days after seeding when covers were installed. Results indicate that covers improved spring establishment of seeded, cool-season turfgrass in a fine-textured soil and in a US transition zone climate by mitigating low temperature extremes and reducing erosion during rainfall. Establishment was similar between drip (SDI and AGD) and sprinkler irrigation, but the use of protective covers is recommended when establishing turfgrass from seed

Effects of Drip Irrigation and Cultivation Methods on Establishment of Seeded Tall Fescue

Subsurface drip irrigation (SDI) is becoming increasingly popular for maintaining turfgrass, in part because it conserves water. However, turf managers considering SDI may wonder if SDI is effective in establishing seeded turfgrass, should the need arise. Also, can verticutting or core aeration be used to establish the seedbed without damaging the buried driplines? Is one of those two cultivation methods better than the other? These questions were evaluated in this study. An aboveground drip irrigation system (AGD) was also evaluated because it has been suggested as a portable method for establishing turfgrass planted along roadsides. Results indicated seeded tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] turf was successfully established with SDI in fine-textured soil in a transition zone climate. Seeded turf established faster with SDI than AGD or overhead sprinkler irrigation. With SDI, establishment was faster when water was applied 2× than 3× or 1× per day (the same amount of water per day was applied in each, but was split into one, two, or three applications). Core aerification and verticutting for seedbed preparation were equally successful in establishing seeded tall fescue using SDI. Buried driplines were not damaged under the conditions of this study, but depths of cultivation and driplines must always be considered to avoid SDI damage