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Automatic control of irrigation in greenhouses by simulation of the water balance in the root zone

Abstract:

To optimize the scheduling of irrigation, the water status in the root zone should be controlled. To this end an automatic control unit using the continuous and remote reading of quick response tensiometers has been conceived. This paper shows that the tensiometer control of a greenhouse irrigation system may be optimized by simulation of the root zone water balance. The model, which has been validated by growing hothouse tomatoes in lysimeter experiments, requires data relating to soil, crop and climate. Simulation allows calculation of the critical soil pressure head, which varies with depth and, for a specific crop-soil combination, especially depends on the evapotranspiration demand and on the presence of a ground watertable. In cases where very low pressure heads prevail, the method suggests an installation depth for the tensiometers. © 1984.