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| Titel |
Sensitivity of water balance and water use efficiency to climate and crop type at an agricultural site |
| VerfasserIn |
C. Brümmer, W. L. Kutsch |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250069835
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| Zusammenfassung |
| The effects of climatic factors and crop type on evapotranspiration (E) and water use
efficiency (WUE) were analyzed using tower-based eddy-covariance data for an agricultural
site in Thuringia, Germany. During ten years of observation, winter wheat (five times) and
winter barley (once) were alternately planted with potato (twice), rapeseed (once) and sugar
beet (once). The seasonal pattern of E was closely linked to growing-season length and
rainfall distribution. Although annual precipitation (P) was highly variable (380-700 mm),
minimum annual E was not less than 250 mm and was limited to 380 mm. However, a
positive correlation between annual P and annual E with E plateauing at high P as was
usually found at forest, grassland and peatland sites could not be observed. Winter wheat
tended to limit annual E and was found to be relatively insensitive with changing annual P
and solar irradiance. A hysteretic relationship between monthly mean values of E and net
radiation (Rn) indicated that E lagged behind the typical seasonal progression of
Rn. Annual means of daytime dry-foliage Priestley-Taylor α much less than the
theoretical maximum of 1.26 for extensive well-watered vegetation showed that E on
an annual basis was either water limited and/or stomatal control of transpiration
must have been prevalent. In all years, a strong linear correlation between monthly
mean values of gross primary production and E resulted in WUE being relatively
constant between 2.5 and 3.5 g C kg-1 H2O. Our study shows that crop selection has
a major impact on the water balance of an agricultural site with the influence of
climatic factors being significantly different than usually found for natural ecosystems. |
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