ISHS Acta Horticulturae 171: I International Symposium on Water Relations in Fruit Crops
SPATIAL AND TIME VARIABILITY OF SOIL MOISTURE IN CITRUS ORCHARDS AS MEASURED BY NEUTRON PROBE |
| Authors: | I. Bautista, G. Cruz-Romero, J.R. Castel, C. Ramos |
| Abstract:
Neutron probe measurements of soil moisture were carried out at weekly intervals in three plots planted to oranges and flood irrigated. Neutron probe access tubes had been placed with different layouts in relation to tree trunk and irrigation border dike. Location, calibration and instrument components of total variance of the estimates of soil moisture and soil moisture changes by the neutron probe technique were evaluated. The location component was always larger by about one order of magnitude than the calibration component, while the instrument component was between two and one order of magnitude lower than the location and calibration components, respectively. The number of tubes required in a plot to assure with 95% probability that the true value of the mean soil water content change was within ± 6 mm of the estimated soil water content change (h) were different for each plot, ranging from 8 to 18, for a typical h between two irrigations of 40 mm. A study on site selection and representativity may allow to reduce the number of access tubes to be read after a certain period of measurements in all tubes initially installed is completed. | |
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