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Calculating the water deficit of cherry orchard by means of spatially resolved approach
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: 2018 ASABE Annual International Meeting 1800906.(doi:10.13031/aim.201800906)
Authors: Nikolaos Tsoulias, Manuela Zude-Sasse
Keywords: ECa, Evapotranspiration, Kc , Precision horticulture, RAW, TAW, Water balance
Abstract In semi-humid climate, spatially resolved analysis of water deficit was carried out in a sweet cherry orchard (Prunus avium 'Gisela' and 'Regina'). The meteorological data were recorded daily by a weather station. The apparent soil electrical conductivity (ECa) was measured at field capacity, and 4 soil samples in 30 cm were gathered for texture, bulk density, and gravimetric soil water content analyses. Furthermore, in 20 samples locations with varying ECa values the root depth was measured to contrast the field-uniform root depth of 1 m commonly used in water balancing.The crop evapotranspiration (ETc; mm/d) was estimated considering the soil water stress coefficient (Ks) and soil surface evaporation coefficient (Ke). These values were implemented in the Geisenheim irrigation model for calculating the water deficit using crop coefficient (Kcb) in the crucial developmental stages: full bloom, end of stone hardening, harvest, and leaf drop. A negative correlation between the ECa and root depth was observed (r = -0.66, p<0.01). In parallel, total available water content in the root zone (TAWRD) correlated positively with the ECa (r = 0.44, p<0.05). Finally, the influence of measured and orchard-uniform root depth of 1 m on the water balance was quantified, pointing to the adaptation of trees to soil properties compromising the spatial variability of water-holding capacity. However, the difference in soil evaporation considering low, medium and high ECa regions proved the reasonability of spatially resolved water balance in orchards.
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