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Comparasion of Crop Water Stress Index (CWSI) and Water Deficit Index (WDI) by using Remote Sensing (RS)

Tanriverdi C., Atilgan A., Degirmenci H., Akyuz A.

Infrastruktura i Ekologia Terenów Wiejskich

2017

nr III/1

879--894

Drought, water scarcity and climate changes are very important threats for agriculture on a global basis. Remote Sensing (RS) is accepted as a technique to collect data and determine water stress indices. Water Stress Indices (WSI) are useful tools to prevent drought and determine irrigation scheduling. The water stress indices are primarily identified as the Crop Water Stress Index (CWSI) and the Water Deficit Index (WDI). The effect of soil background is major problem to establish CWSI especially during early growth stage measurements of canopy temperature (Ts). Hence, WDI is a better index when it comprised with CWSI because of Ts. CWSI and WDI can be determined by two different techniques. These are determined by using measured by using traditional components to collect data and estimated methods by applying RS components to collect necessary data. Estimated method has many advantages when this method compared with measured method. However, estimated method needs some RS components which are infrared gun (IR), sling psychrometer, Spectro radiometer. With the help of these tools, the necessary data are obtained and WDI is determined. By using Spectro radiometer vegetation indices are defined. Among the many vegetation indices, the Normalized Difference Vegetation Index (NDVI) is mostly used one. By using NDVI determination of vegetation cover is easy and accurate technique to establish WDI. Establishing these both stress indices with less fieldwork and by saving money, time and labor conveys the necessary information for agriculturists using remotely sensed data especially for large agricultural fields.

CropSyst model for wheat irrigation water management with fresh and poor quality water

Ouda S. A., Noreldin T., Mounzer O. H., Abdelhamid M. T.

Journal of Water and Land Development

2015

no. 27

41--50

CropSyst model can be used as irrigation water management tool to increase wheat productivity with poor quality water. The objective of this study was to calibrate CropSyst model for wheat irrigated with fresh and agricultural drainage water. To do so, three field experiments were conducted during three successive seasons in Nubaria Agricultural Research Station, Egypt representing the newly reclaimed calcareous soils. In the first season the treatments were 100% crop evapotranspiration (ETc) of fresh water (FW) and 100% ETc of agricultural drainage water (DW), while in the second and the third seasons, the treatments were 100% ETc of FW, 100% ETc of DW, 120% ETc of DW and 130% ETc of DW. From these results one can concluded that deducting 5% of the applied water to all treatments reduced yield by 3, 5 and 7% in the first, second and third growing season, respectively as a result of heat stress existed in the 2nd and 3rd seasons during reproductive phase. Furthermore, deducting 5% of the applied water from all treatments in the vegetative phase only resulted in lower yield losses. Thus, using CropSyst model could guide us to when we could reduce the applied irrigation water to wheat to avoid high yield losses.

Model CropSyst może znaleźć zastosowanie jako narzędzie w zarządzaniu systemem nawodnień wodą niskiej jakości w celu zwiększenia produkcji pszenicy. Przedmiotem przedstawionych badań było skalibrowanie modelu CropSyst do nawodnień pszenicy wodą naturalną i wodą z rolniczych systemów drenarskich. W tym celu przeprowadzono trzy eksperymenty polowe w trzech kolejnych sezonach realizowane w Nubaria Agricultural Research Station w Egipcie na ostatnio zmeliorowanych glebach wapiennych. W pierwszym sezonie warianty eksperymentalne obejmowały: 100% ewapotranspiracji (ETc) wody naturalnej (FW) i 100% ETc wody z systemów drenarskich (DW); w drugim i trzecim sezonie wariantami eksperymentalnymi były: 100% ETc z użyciem FW, 100% ETc z użyciem DW oraz 120% i 130% ETc z zastosowaniem DW. Uzyskane wyniki dają podstawy do wnioskowania, że zmniejszenie ilości wody zastosowanej do nawodnień o 5% we wszystkich wariantach zmniejszyło plony o 3, 5 i 7% odpowiednio w pierwszym, drugim i trzecim sezonie wskutek stresu termicznego, jaki wystąpił w drugim i trzecim sezonie w fazie reprodukcji. Ponadto, zmniejszenie ilości stosowanej wody o 5% jedynie w trakcie fazy wegetatywnej skutkowało mniejszymi stratami plonu. Podsumowując, zastosowanie modelu CropSyst umożliwia nam stwierdzenie, kiedy można ograniczyć ilość wody do nawodnień i uniknąć znaczących strat w plonie pszenicy.