Abstract
Variations in the water profiles of soils under oil palms were monitored using a programmable and automatic neutron and gamma ray radiometric probe. Measurements were made during a drying out phase, followed by a rehydration phase. Soil samples taken when the probe was installed were used for gravimetric calibration and slices were taken from trench walls for densimetric calibration. At the start of the rainy season, the roots utilised water from the surface horizons, and then from prgressively greater depths. Although not clearly demonstrated, capillary rise was strongly suspected of playing a role in this supply of water. These data allowed water balances and the changes in available soil water to be calculated over different periods of time, aswell as the quantities of water absorbed by the oil palms in relation to the rainfall pattern at the plantation.Variations in the water profiles of soils under oil palms were monitored using a programmable and automatic neutron and gamma ray radiometric probe. Measurements were made during a drying out phase, followed by a rehydration phase. Soil samples taken when the probe was installed were used for gravimetric calibration and slices were taken from trench walls for densimetric calibration. At the start of the rainy season, the roots utilised water from the surface horizons, and then from prgressively greater depths. Although not clearly demonstrated, capillary rise was strongly suspected of playing a role in this supply of water. These data allowed water balances and the changes in available soil water to be calculated over different periods of time, aswell as the quantities of water absorbed by the oil palms in relation to the rainfall pattern at the plantation.