TDR Technique for Estimating the Intensity of Evapotranspiration of Turfgrasses.
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Those parameters are the temperature and the volumetric moisture of soil at the depth of 2.5 cm.Evapotranspiration has the character of a modified logistic function with empirical parameters.It assumes the form ETR(θ (2.5 cm), T (2.5 cm)) = A/(1 + B · e (-C · (θ (2.5 cm) · T (2.5 cm)), where: ETR(θ (2.5 cm), T (2.5 cm)) is evapotranspiration [mm · h(-1)], θ (2.5 cm) is volumetric moisture of soil at the depth of 2.5 cm [m(3) · m(-3)], T (2.5 cm) is soil temperature at the depth of 2.5 cm [°C], and A, B, and C are empirical coefficients calculated individually for each of the grass species [mm · h(1)], and [-], [(m(3) · m(-3) · °C)(-1)].
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Affiliation: Institute of Environmental Protection and Development, Wrocław University of Environmental and Life Sciences, Plac Grunwaldzki 24, 50-363 Wrocław, Poland.
ABSTRACT
The paper presents a method for precise estimation of evapotranspiration of selected turfgrass species. The evapotranspiration functions, whose domains are only two relatively easy to measure parameters, were developed separately for each of the grass species. Those parameters are the temperature and the volumetric moisture of soil at the depth of 2.5 cm. Evapotranspiration has the character of a modified logistic function with empirical parameters. It assumes the form ETR(θ (2.5 cm), T (2.5 cm)) = A/(1 + B · e (-C · (θ (2.5 cm) · T (2.5 cm)), where: ETR(θ (2.5 cm), T (2.5 cm)) is evapotranspiration [mm · h(-1)], θ (2.5 cm) is volumetric moisture of soil at the depth of 2.5 cm [m(3) · m(-3)], T (2.5 cm) is soil temperature at the depth of 2.5 cm [°C], and A, B, and C are empirical coefficients calculated individually for each of the grass species [mm · h(1)], and [-], [(m(3) · m(-3) · °C)(-1)]. The values of evapotranspiration calculated on the basis of the presented function can be used as input data for the design of systems for the automatic control of irrigation systems ensuring optimum moisture conditions in the active layer of lawn swards. No MeSH data available. Related in: MedlinePlus |
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Mentions: Figure 7 presents the relation of evapotranspiration to the mean diurnal (θd) or hour (θh) moisture of the surface layer of soil. Figure 7(a) presents the value of ETR and the mean moisture calculated, as in the case of Figure 6, with the time step of Δt = 1 day. For example, for Niweta the mean moisture of the surface layer of soil varied during the 11-day period from about 0.32 m3·m−3 to approximately 0.12 m3·m−3, and similar ranges were observed for the remaining grasses. Meanwhile, for all the grasses the diurnal values of evapotranspiration fell within the range from ~0.5 mm·day−1 when the soil moisture was ~0.1 m3·m−3 to as much as 10 mm·day−1, that is, when the soil moisture was 0.35 m3·m−3. The relation between diurnal evapotranspiration and soil moisture constructed in this way is proportional. Figure 7(b) presents the relation of evapotranspiration, on the example of the 13th of June (3rd day), calculated with the time step Δt = 1 h, with the mean soil moisture at a given hour. That relation is indeterminate, as the range of the changes of mean moisture during a 24-hour period is approximately 0.03 m3·m−3, and the variations in evapotranspiration are caused by diurnal temperature variation. Summarizing the analyses of Figures 6 and 7, we conclude that the construction of the relation of evapotranspiration to soil temperature at the depth of 2.5 cm and to its volumetric moisture cannot be conducted separately, with the same time step Δt. Therefore, three-dimensional surfaces were constructed (further referred to as maps), described by 3 variables. In the horizontal plane, the coordinates are the volumetric moisture of soil and its temperature, measured at the depth of 2.5 cm, while the vertical dimension is evapotranspiration. |
View Article: PubMed Central - PubMed
Affiliation: Institute of Environmental Protection and Development, Wrocław University of Environmental and Life Sciences, Plac Grunwaldzki 24, 50-363 Wrocław, Poland.
No MeSH data available.