Environmental Engineering Reference
In-Depth Information
Agro-management Components
AgroManagement: Rule Based Modelling of Technical Management
The AgroManagement component was developed by CRA and is designed to
implement field management actions during simulation. An agricultural activity is
defined, in this context, as a production enterprise such as a crop rotation, i.e. an
assemblage of crops, an orchard etc., associated with a production system charac-
terized in terms of outputs and inputs such as high input, high output (e.g., irrigated,
high nitrogen fertilization, minimum tillage). Such an integrated system must be
implemented in a way that imitates as closely as possible farmers' behaviour.
Limiting the drivers of the decision making process to the biophysical system
implies that each action must be triggered at run time via a set of rules which can
be based on the state of the system, on constraints of resource availability, or on the
physical characteristics of the system. However, simulating management in a
component-based system poses challenges in defining a re-usable framework
which is able to account for the complete range of agricultural management
technologies applied to particular enterprises. Finally, the implementation of
management must allow different approaches to be used for modelling its impact
on different model components.
The AgroManagement component formalizes the decision making process in
models called rules, and the drivers of the implementation of the impact on the
biophysical system as a set of parameters encapsulated in data-types called impacts.
Rules and impacts are both easily extendable, thus allowing a wide range of model-
ling approaches to be used. Furthermore, the information on the biophysical system is
passed through a data-type called states, which can also be extended in case new
rules require additional variables. The outputs from the management actions, applied
as a result of rules evaluated at run-time, needed to provide the simulation output
(output to a text file, an XML file or a database are all currently available) can be
fully customized by the user and added to without recompiling the component.
Currently, the management actions which can be implemented are nitrogen
fertilization (mineral and organic), tillage, irrigation, pesticide application, and crop,
tree, and grassland operations. The software implementation is such that new agro-
management typologies, and new actions within the typologies, can be easily added.
The rule-based model is characterized by three main sections:
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Inputs: states of the system and time
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Parameters specific for each rule (values are compared to states of the system via the
rule model)
A model which returns a true/false output
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Rules, which are based on relative date or on a set of state variables, are
implemented as a class encapsulating their parameter declarations and tests of
pre-conditions (this also allows management configuration files to be validated using
pre-condition tests). One feature of interest is that implementing the rule approach
allows the formalization of what is generically referred to as “expert knowledge”.
