Measurement and estimation of plastic greenhouse reference evapotranspiration in a Mediterranean climate

2010 ◽  
Vol 28 (6) ◽  
pp. 497-509 ◽  
Author(s):  
M. D. Fernández ◽  
S. Bonachela ◽  
F. Orgaz ◽  
R. Thompson ◽  
J. C. López ◽  
...  
Agriculture ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 124
Author(s):  
Gonçalo C. Rodrigues ◽  
Ricardo P. Braga

The FAO-56 Penman–Monteith (PM) equation is regarded as the most accurate equation to estimate reference evapotranspiration (ETo). However, it requires a broad range of data that may not be available or of reasonable quality. In this study, nine temperature-based methods were assessed for ETo estimation during the irrigation at fourteen locations distributed through a hot-summer Mediterranean climate region of Alentejo, Southern Portugal. Additionally, for each location, the Hargreaves–Samani radiation adjustment coefficient (kRs) was calibrated and validated to evaluate the appropriateness of using the standard value, creating a locally adjusted Hargreaves–Samani (HS) equation. The accuracy of each method was evaluated by statistically comparing their results with those obtained by PM. Results show that the calibration of the kRs, a locally adjusted HS method can be used to estimate daily ETo acceptably well, with RMSE lower than 0.88 mm day−1, an estimation error lower than 4% and a R2 higher than 0.69, proving to be the most accurate model for 8 (out of 14) locations. A modified Hargreaves–Samani method also performed acceptably for 4 locations, with a RMSE of 0.72–0.84 mm day−1, a slope varying from 0.95 to 1.01 and a R2 higher than 0.78. One can conclude that, when weather data is missing, a calibrated HS equation is adequate to estimate ETo during the irrigation season.


2016 ◽  
Vol 11 (3) ◽  
pp. 158 ◽  
Author(s):  
Vito Marchione ◽  
Mariano Fracchiolla

In Mediterranean areas, very scarce rainfalls during the summer season are a limiting factor to the sowing and managing of turfgrasses. This work evaluates the response to different irrigation regimes (50 or 75% of reference evapotranspiration) of <em>Cynodon dactylon</em> (L.) Pers. cv <em>Transcontinental</em>, <em>Paspalum</em> <em>vaginatum</em> Swartz cv <em>Salam</em>, <em>Pennisetum</em> <em>clandestinum</em> (Chiov.) Hochst. cv <em>AZ1</em>, <em>Stenotaphrum</em> <em>secundatum</em> (Walt.) Kuntze cv <em>Palmetto</em> and <em>Zoysia</em> <em>japonica</em> Steud. cv <em>El</em> <em>Toro</em>. Performance of turfgrasses was evaluated in term of turf quality, colour index and ground cover. Only when rainfalls were scarce, water regime restoring the 75% of the evapotranspiration (ET<sub>o</sub>) showed significant effects. Under rainy conditions, the restoration of only the 50% of ET<sub>o</sub> was able to give highly acceptable values. The best performance was observed for <em>Z. japonica</em>, <em>C. dactylon</em> and <em>P. vaginatum</em>, whereas <em>P. clandestinum</em> and <em>S. secundatum</em> showed lower adaptability to water stress.


2010 ◽  
Vol 29 (1) ◽  
pp. 91-92 ◽  
Author(s):  
M. D. Fernández ◽  
S. Bonachela ◽  
F. Orgaz ◽  
R. B. Thompson ◽  
J. C. López ◽  
...  

2010 ◽  
Vol 28 (6) ◽  
pp. 511-511
Author(s):  
M. D. Fernández ◽  
S. Bonachela ◽  
F. Orgaz ◽  
R. B. Thompson ◽  
J. C. López ◽  
...  

Author(s):  
I.G.C. Kerr ◽  
J.M. Williams ◽  
W.D. Ross ◽  
J.M. Pollard

The European rabbit (Oryctolagus cuniculus) introduced into New Zealand in the 183Os, has consistently flourished in Central Otago, the upper Waitaki, and inland Marlborough, all areas of mediterranean climate. It has proved difficult to manage in these habitats. The 'rabbit problem' is largely confined to 105,000 ha of low producing land mostly in semi arid areas of Central Otago. No field scale modifications of the natural habitat have been successful in limiting rabbit numbers. The costs of control exceed the revenue from the land and continued public funding for control operations appears necessary. A system for classifying land according to the degree of rabbit proneness is described. Soil survey and land classification information for Central Otago is related to the distribution and density of rabbits. This intormation can be used as a basis for defining rabbit carrying capacity and consequent land use constraints and management needs. It is concluded that the natural rabbit carrying capacity of land can be defined by reference to soil survey information and cultural modification to the natural vegetation. Classification of land according to rabbit proneness is proposed as a means of identifying the need for, and allocation of, public funding tor rabbit management. Keywords: Rabbit habitat, rabbit proneness, use of rabbit prone land.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 512c-512
Author(s):  
R.C. Beeson

The objective of this study was to determine crop coefficients (KC) for Ligustrum japonica growing in three container sizes using the Penman equation to calculate reference evapotranspiration (ETR). Rooted cuttings were transplanted into 3-liter containers and upcanned as needed into 10- and 23-L containers. Production was scheduled such that a series of plants in each container size were about 2 months from commercial marketable size every 4 months. Beginning 1 Jan. 1995 until 31 Dec. 1996, three uniform plants of each size were suspended in weighing lysimeters and surrounded by similar size plants filling an area 3.7 by 4.9 m. Plants within each area were overhead irrigated at 2000 h as needed, based on a 30% moisture allowed deficit. Plants were exchanged every 4 months such that the annual mean size was that of a marketable plant. Actual evapotranspiration (ETA) was calculated from half-hour measurements of each plant's weight and adjusted for rainfall. From these and daily calculated ETR, KC were determined for each size of container. KCs ranged from 1.06 to 1.50 when ETA was converted to mm/day based on allocated bed space. Comparisons of volumes of supplemental irrigation to ETA and effects of assumptions required in converting ETA to mm/day will be discussed.


1994 ◽  
Vol 30 (1) ◽  
pp. 23-32 ◽  
Author(s):  
John R. Argue

The water resources crisis facing countries of the Mediterranean Basin is reflected, in diminished form, in the semi-arid, “Mediterranean-climate” zone of Australia. Some creative solutions involving the collection, treatment, storage, retrieval and use of storm runoff to replace the component of mainssupplied water presently used for “second quality” purposes, are emerging in Adelaide, capital city of South Australia. The paper describes one initiative being taken to achieve source control of stormwater – quantity and quality – in mixed-density residential streets. The resulting streetscape is suitable for use in both “greenfields” and re-development projects. The paper explores the hydrological/hydraulic performance of the system and shows that it satisfies all theoretical- requirements for safety in the full range of flooding up to and including the “once in 100-years” event. The new streetscape holds the following advantages over conventional streetscapes : reduced peak outflows, greatly improved effluent water quality, aids “greening” of the landscape, potential for aquifer recharge where appropriate, aquiferretrieved groundwater can replace mains water used for irrigation, “nuisance” flows are fully contained (no surface appearance), major flows only occupy the swale, street residences are less flood prone and the streetscape fits more harmoniously into undulating terrain.


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