Environmental Engineering Reference
In-Depth Information
MassBalance: A Library of Mass Balance Tests
The MassBalance component was developed by CRA. It implements equations of
balance in discrete code units (strategies). The water and the nitrogen balance are
currently implemented. At each time step the component computes the active balances,
and outputs the values. Each balance has a threshold parameter as maximum departure
from zero allowed; this threshold can activate a flag at run time. The component,
which can be extended, is designed to be used either in the test phase of a new
modelling solution, or permanently as a check on correct functioning.
RootDistribution: Roots Growth and Distribution
The RootDistribution component, which was developed by INRA, estimates the
partitioning of fine roots between layers in the soil profile. Only one model is currently
available, derived from Hi-sAFe 3D model (Root Voxel Automaton, Mulia
2005
;
Mulia and Dupraz
2006)
. From the daily fine root growth and death, the soil layer
thickness and the water extraction of the previous day, the allocation of root length
and biomass to the different soil layers is estimated using an opportunistic growth
paradigm. Parameters can be fitted to adjust the water and distance to collar sensitivity
so that root profiles of most species can be simulated. It is assumed that the
horizontal distribution of crop roots is homogeneous, given that the root distribution
is a one-dimensional simplification of the system.
Tree: Woody Plant Growth and Quality
The Tree component was developed by INRA. It is a generic woody plant
model designed to simulate grapevines, fruit trees and timber trees; it is currently
parameterized for grapevines. It simulates crop growth, production and product
quality. Its basic features are similar to those implemented in the Crop component:
temperature drives crop development, and intercepted radiation determines the
potential growth rate that can be reduced by water or nitrogen limitations. Dry
matter and nitrogen are partitioned between the growing organs on the basis of
partitioning tables (Nendel and Kersebaum
2004
; Vivin et al.
2002
; Wermelinger
and Koblet
1990)
. Some features are specific to woody crops. Where these crops
are planted in rows, as is generally the case, their canopy is heterogeneous and
the Tree component converts the daily carbon increment into an increase in crown
dimensions (needed in the Light interception component, Pronk et al.
2003)
. Woody
crops are perennial so carbon and nitrogen can be stored during the annual crop
cycle and used during the next cycle (particularly at bud break) (Castelan-Estrada
2001)
. The Tree component calculates variables that define fruit crop quality,
which is important for crops such as grapevines or apple trees. For grapevines,
the dynamics of fruit water and sugar contents depend on the thermal time during
the phase of grape growth after the onset of ripening (veraison) (Ollat et al.
2002)
.
