Etude de la consommation en eau de l'association cocotier - cacaoyer par l'analyse de profils hydriques

Moisture stress is the main limiting factor for perennial crops in the cropping conditions of P.T Multi-agro Corporation (South Sumatra, Indonesia). A research based on the use of a capacitive moisture probe (Sentry 200 AP, Troxier) was carried out in order to compare the water consumption between coconut-cocoa intercropping and single crops. The measurement method consists in introducing a probe in a CPV pipe . Mis-functioning of the experimental device due to the presence of air between the soil and the pipe lead us to set up a new experimental device which appreciably increased the accuracy and reliability of the results obtained. The drying out profile obtained after an artificial flood of the volume of soil located around the pipe enables to assess the duration of the soil drying out. The low value obtained (10 h) characterizes a soil water economy very draining. Between 15 and 130 centimeters, the field capacity varies from 23 to 30% moisture by volume. The comparison of water stock variation after three months of dry season between coconut-cocoa intercropping and single crops underlines that in both cases the water storage of the first 160 centimeters of soil is fully consumed whereas, more in depth, water storage use is more efficient for coconut-cocoa intercropping than for single crops. A rough estimation of the fractional extractable water enables to assess the water consumption in a non constrained situation. The value obtained (6.8 millimeters) is relatively high since the deep layers of the soil are not taken into account in the calculation. The results presented in the present report do not take into account all the initially planed repetitions and remain to be confirmed by further experiments to be cared out during the next rainy season with the new experimental device we developed. (Résumé d'auteur)