Environmental Engineering Reference
In-Depth Information
(Confalonieri et al.
2006)
. The first two models are generic crop simulators, based
respectively on the simulation of net and gross photosynthesis; the latter is a model
specifically for rice simulations. CropSyst simulates net daily biomass accumulation
using two approaches: the first is based on the concept of radiation use efficiency
(RUE); the second is a vapour pressure - corrected Transpiration Use Efficiency
approach. Each day, the minimum of the two biomasses is taken. CropSyst simulates
daily biomass partitioning as a function of Specific Leaf Area at emergence,
cumulated biomass, and an empiric parameter representing the partitioning of
biomass between stems and leaves. WOFOST simulates the daily fixation of CO
2
(gross photosynthesis), the growth and maintenance respirations and a dynamic
partitioning between leaves, stems and storage organs. WARM is based on the RUE
approach, accounting for limitations to RUE due to temperature, senescence,
saturation of the enzymatic chains and diseases. A dynamic approach for biomass
partitioning of assimilates into stems, leaves and storage organs is also adopted in
this case, driven by a single input parameter.
The CropML - WARM component uses a micrometeorological component,
TRIS (Temperature in paddy-RIce Simulation). The TRIS component simulates the
floodwater effect on the vertical soil thermal profile in paddy rice fields. TRIS is
particularly important for rice simulations in temperate environments, where there
is a significant effect of floodwater on temperature (one of the main driving
variables in cropping systems models). Two alternative models were implemented,
a mechanistic and an empirical one, for use according to data availability. The first
is based on the solution of surface energy balance equations and estimates the
temperature of floodwater, of each 10 cm canopy layer from the air-water interface
to the top of the canopy, of the meristematic apex, and of the canopy. The model
has an hourly time step. Context strategies allow also the generation or estimation
of canopy and meteorological variables according to their availability in the domain
classes. If needed, hourly inputs can be generated using the CLIMA libraries
(Fig.
4.2
). Maximum and minimum daily temperatures of floodwater, meristematic
apex, and mid-canopy are calculated. The empirical model is based on modified
Gaussian filters which reproduce the smoothing effect of water on daily thermal
extremes, and the water heat storage capacity.
The component can be extended through the implementation of alternative
approaches, e.g. for the simulation of meteorological variables into the canopy
profile.
Diseases: Air-Borne Plant Diseases
The Diseases component was developed by CRA and UNICATT. It allows the
impact of plant disease epidemics on plant growth and yield to be estimated. It consists
of four modules providing a generic frame to simulate disease development:
-
Disease progress
-
Inoculum pressure (initial conditions)
-
Impact on plants
-
Agricultural management impact on pathogen populations
