Crop coefficients of bare soil under Gezira conditions
2004
Ahmed, S.B.,University of Gezira, Wad Medani (Sudan
The field experiment was conducted at Gezira Research Station farm (GRS) in Wad Medani during the rainy period of 2002 and the winter period of 2003, to determine the crop coefficient (kc) for bare soil. Soil samples were taken to determine actual evapotranspiration (ETc) and also meteorological data were collected during the experimental period to estimate reference evapotranspiration (ETo) using Penman-Monteith formula, and CROP-WAT soft ware package. The results showed that it is not appropriate to determine the (ke) value for Gezira cracking soils, from a limited number of soil samples. Avery intensive and extensive soil sampling is needed as done by Farbrother in he seventies. The recommended (kc) of 0.5 should not be used to calculate the first irrigation water and dependable kc values are obtained from the second irrigation. Significant changes in soil moisture content are found mainly in the upper zones from 0-60cm. Changes below 60cm are very small. It is recommended that, in such studies on soil moisture in clays, large plots are to be used
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