Articles
Validation of the ‘Virtual Lysimeter’, a decision support system for soil grown greenhouse crops
Article number
1409_42
Pages
327 – 334
Language
English
Abstract
Strict rules are in force for Dutch greenhouse horticulture to reduce water bound emissions.
For soil-grown crops a ‘duty of care’ to tune fertigation to the crop demand is imposed.
To enable growers to meet this requirement the ‘virtual lysimeter’ (VL) has been developed as DSS. It consists of a combination of an ET model and a soil model.
By analogy to a physical lysimeter, the VL represents a specific soil-crop situation and the associated in- and outputs of water flows.
The combination of ET model and soil model creates a powerful tool for growers that takes site-specific soil analysis and climate computer data and shows the grower a detailed water balance overview as well as a potential leaching for the next irrigation event.
The VL presents three succinct graphics with the cumulative values of irrigation, ET, calculated leaching, and capillary flow; the course of the calculated moisture content in the individual three soil layers; and the instantaneous flows between layers.
This gives the grower insight into his soil conditions and allows for tuned and optimized fertigation aiming at minimal leaching.
Since water flows are the means of transport for nutrients and plant protection products (PPPs), this tool can be used to control emissions in a targeted way and reduce them to minimum proportions.
This paper focuses on the validation of the VL in commercial greenhouses where physical lysimeters were installed.
During an initial phase, the model was calibrated using physical lysimeters.
In a second phase, the VL was validated for two years at two commercial greenhouses, with chrysanthemum and with fruit vegetables, using the measured leachates of the installed physical lysimeters.
For soil-grown crops a ‘duty of care’ to tune fertigation to the crop demand is imposed.
To enable growers to meet this requirement the ‘virtual lysimeter’ (VL) has been developed as DSS. It consists of a combination of an ET model and a soil model.
By analogy to a physical lysimeter, the VL represents a specific soil-crop situation and the associated in- and outputs of water flows.
The combination of ET model and soil model creates a powerful tool for growers that takes site-specific soil analysis and climate computer data and shows the grower a detailed water balance overview as well as a potential leaching for the next irrigation event.
The VL presents three succinct graphics with the cumulative values of irrigation, ET, calculated leaching, and capillary flow; the course of the calculated moisture content in the individual three soil layers; and the instantaneous flows between layers.
This gives the grower insight into his soil conditions and allows for tuned and optimized fertigation aiming at minimal leaching.
Since water flows are the means of transport for nutrients and plant protection products (PPPs), this tool can be used to control emissions in a targeted way and reduce them to minimum proportions.
This paper focuses on the validation of the VL in commercial greenhouses where physical lysimeters were installed.
During an initial phase, the model was calibrated using physical lysimeters.
In a second phase, the VL was validated for two years at two commercial greenhouses, with chrysanthemum and with fruit vegetables, using the measured leachates of the installed physical lysimeters.
Authors
W. Voogt, J. Stoenner, A. van Winkel, G. Franken
Keywords
drainage, irrigation scheduling, leaching, lysimeter, soil model, water flow
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