Analyses of Spring Barley Evapotranspiration Rates Based on Gradient Measurements and Dual Crop Coefficient Model

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis

Gabriela Pozníková¹  Milan Fischer¹  Eva Pohanková¹  Miroslav Trnka² 

[1] Department of Agrosystems and Bioclimatology, Faculty of Agronomy, Mendel University in Brno, Zemědělská 1, 613 00, Brno, Czech Republic;Department of Climate Change Impacts on Agroecosystems, Global Change Research Centre AS CR, v. v. i., Bělidla 986/4a, 603 00, Brno, Czech Republic;

关键词: evapotranspiration;    dual crop coefficient model;    Bowen ratio/energy balance method;    transpiration;    soil evaporation;    spring barley;   

DOI  :  10.11118/actaun201462051079

来源: DOAJ

【 摘 要 】

The yield of agricultural crops depends on water availability to a great extent. According some projections, the likelihood of stress caused by drought is increasing in future climates expected for the Central Europe. Therefore, in order to manage agro-ecosystems properly, it is necessary to know water demand of particular crops as precisely as possible. Evapotranspiration (ET) is the main part of water balance which takes the water from agro-ecosystems away. The ET consists of evaporation from the soil (E) and transpiration (T) through the stomata of plants. In this study, we investigated ET of spring barley 1-ha field (Domanínek, Czech Republic) measured by Bowen ratio/energy balance method during growing period 2013 (May 8 to July 31). Special focus was dedicated to comparison of barley ET with the reference grass ETo calculated according FAO-56 model, i.e. the determination of barley crop coefficient (Kc). This crop coefficient was subsequently separated into soil evaporation (Ke) and transpiration fraction (Kcb) by adjusting soil and phenological parameters of dual crop coefficient model to minimize the root mean square error between measured and modelled ET. The resulting Kcb of barley was 0.98 during mid-growing period and 0.05 during initial and end periods. According to FAO-56, typical values are 1.10 and 0.15 for Kcb mid and Kcb end, respectively. Modelled and measured ET show satisfactory agreement with root mean square error equal 0.41 mm. Based on the sums of ET and E for the whole growing season of the spring barley, ET partitioning by FAO-56 dual crop coefficient model resulted in E/ET ratio being 0.24.

【 授权许可】

Unknown