Effect of the initial soil moisture content on the spatial distribution of the water retention |
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Authors: | H Merdun R Meral A Riza Demirkiran |
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Institution: | 1.Department of Agricultural Engineering,Kahramanmara? Süt?ü ?mam University,Kahramanmara?,Turkey;2.Department of Soil Science, Faculty of Agriculture,Kahramanmara? Süt?ü ?mam University,Kahramanmara?,Turkey |
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Abstract: | The initial soil moisture content affects the water flow and solute transport through the vadose zone, but researchers are
in disagreement about the extent and nature of its effects. Better understanding of the initial moisture effect on the water
movement will help to prevent groundwater contamination and increase crop production by improving the efficiency of water
use in irrigation practice. Therefore, in this study, the effect of the initial moisture content on the spatial distribution
of the water retention was investigated in the field. A total of 4 cm of water was applied to duplicate plots with each of
three initial moisture conditions within 2 h using a rainfall simulator. Following the application and a 2-h redistribution
period, 100 soil samples were taken from different depths of each plot using a grid sampling system to be analyzed for their
gravimetric water content in the laboratory. Statistical and geostatistical analyses were performed to analyze the spatial
structure of the collected data. The results showed that the preferential flow was more evident in the case of the dry initial
soil water content than for the two wetter initial conditions. Both the classical and geostatistical analyses supported that
the overall water retention was uniformly distributed throughout the profile except at 20–30 cm, where the coefficient of
variation and the percent nugget to total semivariance ratio were high, indicating some degree of preferential flow through
large pores (macropores). These results suggest that similar studies should be conducted on different field soils under more
different initial moisture conditions so that the effect of the macropores on the water flow and chemical transport can be
better understood.
Published in Russian in Pochvovedenie, 2008, No. 10, pp. 1241–1249. |
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