Plantas Ornamentales

ARTICLE IN PRESS
Biosystems Engineering (2007) 96 (3), 419–425
doi:10.1016/j.biosystemseng.2006.12.002
SW—Soil and Water

Adaptation of an Automatic Irrigation-control Tray System
for Outdoor Nurseries
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R. Caceres; J. Casadesus; O. Marfa
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Departament de Tecnologia Hortı´ cola, Institut de Recerca i Tecnologia Agroalimentaries (IRTA), Centre de Cabrils, Cra. de Cabrils s/n 08348Cabrils, Catalonia, Spain; e-mail of corresponding author: rafaela.caceres@irta.es
(Received 4 April 2006; accepted in revised form 4 December 2006; published online 29 January 2007)

Inefficiency in water and nutrient management in outdoor nurseries causes environmental concerns. In this
sense, the irrigation-control system should automatically modulate irrigation in accordance with waterconsumption by the substrate–plant system. The irrigation-control tray method (ICT), which is applied
extensively in greenhouse plants raised in grow bags for horticulture production, has been successfully adapted
to the specific conditions of plants grown outdoors in containers. The prototype was employed to irrigate
plants during the entire experiment (18 months). The performance of the ICTmethod was comparable to the
tensiometric method that it is a sufficiently proven method. The plant biomass was not significantly different
between the two methods and also the irrigation events were comparable.
r 2006 IAgrE. All rights reserved
Published by Elsevier Ltd

1. Introduction

1.1. Irrigation-activation systems

It is becoming more necessary for ornamental plant
nurseries to beequipped with irrigation-management
systems to improve water-use efficiency and reduce the
amount of nutrients that leach into the soil (Schuch &
´
Burger, 1997; Gonzalez, 1998; Bilderback, 2001). The
cost of water and fertiliser usually represents a relatively
low percentage of total production costs, which is why
nurseries often do little to reduce consumption of these
inputs. However,environmental policies now tend to
limit excessive use of water and fertiliser (Biernbaum,
1992; European Parliament, 2000).
Bearing in mind that outdoor ornamental plant
nurseries grow a wide variety of species and use different
formats, strategies to promote water conservation
require to consider many different factors, such as the
needs of different species, the distribution of growingcontainers, and the design and maintenance of irrigation
systems (Bilderback, 2002; Garber et al., 2002).
To increase irrigation efficiency in a group of
homogeneous plants in a nursery (i.e. plants of the
same species and of similar size), it is necessary to
determine the dosage of water to be applied and the
criteria for activating the irrigation system.

Irrigation dosage is based onsubstrate characteristics,
container volume and leachate-fraction percentage
(Salas & Urrestarazu, 2001; Moreno, 2003).
In outdoor ornamental plant nurseries, irrigation is
usually activated empirically, which means irrigation
dosage and frequency are not based on objective criteria
(Michelot, 2000). It is very common for irrigation to be
programmed at regular time intervals without taking
intoaccount objective parameters such as substrate
moisture (Lieth & Burger, 1989; Biernbaum, 1992). The
aim is for irrigation to be activated automatically when
plants need it, while bearing in mind water-retention
capacity of the substrate and plant water consumption.
Many methods have been described and sensors have
been developed that provide reliable information so
irrigation can be managedobjectively (Biernbaum &
Versluys, 1998; Salas & Urrestarazu, 2001). However,
often the sensors are expensive and not mechanically
robust enough for use in outdoor nurseries (Biernbaum,
1992). A few methods for outdoor nurseries stop the
irrigation programme only when enough rain has fallen
(Bilderback, 2001). This area is worth developing for
nurseries located in regions with high...