P. Janssens, F. Elsen , A. Elsen , T. Deckers, H. Vandendriessche
Pear growing (Pyrus Communis ‘Conference’) is an important part of horticulture in Belgium and The Netherlands. Drip irrigation techniques are implemented to achieve maximum production with a high fruit size distribution. The financial return of fruits having a diameter of ≥60 mm is twice the return of smaller sized fruits (≤55 mm). Maximum fruit size distribution and high productivity on ‘Conference’ pear trees can be achieved by applying regulated deficit irrigation (RDI). However, unpredictable summer rains and drought periods make it difficult to establish the optimal irrigation thresholds.
To overcome these difficulties, an adapted Soil Water Balance model is presented to monitor the evolution of soil water content in the root zone on a daily basis. The input parameters for the model are soil water retention characteristics, rain, irrigation events and evapotranspiration. A specific algorithm has been developed for drip irrigation and tree transpiration in an orchard with weed free strips under the trees and grass strips between tree rows. Gravimetric moisture determination is used to calibrate the model during the growing season. The performance of the model was studied in three commercial orchards in the period 2008-2009. A significant correlation (R>0.80) was observed between predicted and observed soil water content. It illustrates the possibilities of the approach to use the soil water balance model as a base to schedule the irrigation for pear trees under orchard conditions with sufficient accuracy.
Janssens, P., Elsen , F., Elsen , A., Deckers, T. and Vandendriessche, H. (2011). ADAPTED SOIL WATER BALANCE MODEL FOR IRRIGATION SCHEDULING IN 'CONFERENCE' PEAR ORCHARDS. Acta Hortic. 919, 39-56
DOI: 10.17660/ActaHortic.2011.919.5
soil water content, regulated deficit irrigation (RDI), root pruning

Acta Horticulturae