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Closed system for water and nutrient management in horticulture

Throughout Europe, current horticultural practices cause very large amounts of water and nutrients to be wasted in the environment. To avoid this, and to increase possibilities of controlling crop growth and quality, water and individual nutrients should be supplied independently and in proportion to the plant's needs, rather than supplying excessive water and nutrients together. In this project, a holistic and multidisciplinary approach - combining modelling and experimental research in plant physiology, substrate physics and chemistry, sensor technology, machine learning, control and optimisation techniques, and economics - is being adopted to reach its objectives. In addition, the end users play a considerable role in the project, and their experience will help test the integrated system under applied research conditions in the final year of the project.

The primary objective of CLOSYS is zero nutrient pollution and minimum water use in greenhouse cultivation. This project aims to achieve crop production sustainability by developing a 'CLOsed SYStem for water and nutrients in horticulture'. In this system, the water and nutrients are continuously re-used. Pollution will be minimised by controlling the input of resources rather than by end-of-pipe measures. Besides aiming at sustainability, other important aspects are enhancing crop quality and safety, and controlling the timing of production, the latter being increasingly important in order for production to be timely and responsive to consumer demand.
Within this overall objective, a number of other critical goals are envisaged in order to complete the project successfully, such as the development of mechanistic plant and substrate models with self-learning properties, non-invasive sensors for plant and substrate characteristics, improved growth substrates, and building a real-time process controller and 'expert system'.

Progress to Date
1) Plant sensor
Knowledge is being applied to develop further an imaging sensor that can be used for the early detection of stress in plants grown in greenhouses. The prototype development is finished.
2) Plant physiology
The prototype mechanistic model for sweet pepper and rose plants, a self-learning process, was tested on data from greenhouse trials, and consisted of a weekly auto-calibration of the simulation results on actual plant data from sensors measuring photosynthesis and reflectance.
3) Substrate physics
To tune the mineral supply so that, at the root level, the rose and sweet pepper plants' demand is met instantly, four main tasks were pursued:
a. characterisation of the dynamics and heterogeneity of water and minerals within the slab
b. determination of substrate properties
c. development of models of substrate dynamics
d. design of improved stone wool slabs.
4) Systems integration
An expert system is being developed that will determine the irrigation schedule and the nutrient supply plan. This system should lead to 'fertigation plans' that will be sensitive to weather forecasts.

The project was carried out with two different crops (roses and sweet peppers), which are very important economically throughout Europe. As the system has a mechanistic basis, a generic structure and self-learning properties, the system can be easily applied to other crops as well. The work was grouped in five themes:
1) Plant sensor
Non-invasive, on-line sensors, measuring important parameters of the crop, were developed.
2) Plant physiology
Experimental and modelling research focused on the development of a dynamic crop model that predicted the demand for, and uptake of, water and the individual ions by crops.
3) Substrate physics
Multiflow computer fluid dynamics was used to develop a substrate model that predicted the strategy of fertigation to meet the demand of the roots.
4) Systems integration
The models and sensors were integrated in an expert system and a real-time control system for ion-selective nutrient and water supply. To obtain total system integration, all sub-systems will be implemented within a technical infrastructure consisting of a modular hardware platform.
5) Testing & dissemination
In the last year of the project, the integrated system will be tested on a near-practical level, and results will be disseminated to the horticultural industry, students and policy-makers.


Scientist responsible for the project

P.O. BOX 16
6700 AA Wageningen
Netherlands (The) - NL

Phone: +31 317 475802
Fax: +31 317 423110


Project ID QLRT-1999-31301
Organisation Plant Research International B.V.
Area 5.1.1
Start date 01 February 2001
Duration (months) 48
Total cost 2 638 324 €
Total EC contribution   1 657 851 €
Status Ongoing
Web address of the project

The partners

  • Centre Technique Interprofessionel des Fruits et Légumes , France - FR

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