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- Joel, Abraham, et al.
(författare)
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Mapping suitability of controlled drainage using spatial information of topography, land use and soil type, and validation using detailed mapping, questionnaire and field survey
- 2009
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Ingår i: Hydrology research. - : IWA Publishing. - 1998-9563 .- 2224-7955 .- 0029-1277. ; 40, s. 406-419
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Tidskriftsartikel (refereegranskat)abstract
- Controlled drainage has the potential to moderate the variability in temporal water runoff and to control N leaching. The objective of this study was, firstly, to present a feasibility study to identify land that is suitable for installation of controlled drainage in four counties in the coastal areas of southern Sweden and, secondly, to present a methodology to validate land that has been identified as suitable. In the feasibility study, digital data of land use, slope gradient and soil types were individually rated and combined into suitability classes. Of 726,000 ha cultivated land, 21% was classified as very highly or highly suitable, 13% moderately suitable and 6% marginally suitable. The validation study comprised analyses of the study areas from (i) digitized information on existing drainage network associations, provided by regional authorities, (ii) a questionnaire study directed to land users and (iii) physical investigation of soil properties of chosen fields on 82 farms. At least 67% of the land being appointed as being suitable for controlled drainage in the feasibility study was drained or had a drainage demand. There was a high correspondence between the results obtained in the validation study as compared to the feasibility study.
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| 2. |
- Messing, Ingmar, et al.
(författare)
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Bygg inte på kultur- och åkermark
- 2009
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Ingår i: Upsala nya tidning. - Uppsala. - 1104-0173. ; :2 maj, s. 4-
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 3. |
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| 4. |
- Messing, Ingmar, et al.
(författare)
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Methods to estimate lettuce evapotranspiration in greenhouse conditions in the central zone of Chile
- 2009
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Ingår i: Chilean Journal of Agricultural Research. - 0718-5820. ; 69, s. 60-70
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluates five methods to estimate crop evapotranspiration in greenhouse conditions. It compares their performance in relation to the evapotranspiration directly determined from water balance measurements (ET(lys)) in an irrigated lettuce (Lactuca sativa L.) crop during 9 weeks. Daily values of the reference evapotranspiration (ETo) from Class A pan (CAP), Piche atmometers (ATM), Andersson evaporimeters (ANE), FAO-Radiation (FRE) and FAO-Penman-Monteith (PME) equations were compared. The methods showed similar temporal variations but at different ranges as follows: ANE < CAP < FRE < PME < ATM. Furthemore, ETo had a clear correlation with solar radiation. Crop coefficients (Kc = ET(lys)/ETo) varied somewhat amongst the methods, but trends were identified for two periods: in the first week, the overall mean Kc was 0.3 (+/- 0.1) and in weeks 2 to 9 on average 0.6 (+/- 0.3). The greenhouse values of Kc were lower than those generally adopted for lettuce in field conditions. In terms of irrigation design, crop evapotranspiration can be estimated by the methods in this study, on the condition that the appropriate crop coefficients are applied. The fact that ANE showed values closest to those of ETlys, along with cost and management convenience, makes it an advantageous alternative as compared to the other methods.
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