# -*- coding: utf-8 -*-
# Copyright (c) 2004-2014 Alterra, Wageningen-UR
# Allard de Wit (allard.dewit@wur.nl), April 2014
from copy import deepcopy
from ..traitlets import Float, Int, Instance, AfgenTrait
from ..decorators import prepare_rates, prepare_states
from ..util import limit, merge_dict
from ..base_classes import ParamTemplate, StatesTemplate, RatesTemplate, \
SimulationObject, VariableKiosk
[docs]class WOFOST_Root_Dynamics(SimulationObject):
"""Root biomass dynamics and rooting depth.
Root growth and root biomass dynamics in WOFOST are separate processes,
with the only exception that root growth stops when no more biomass is sent
to the root system.
Root biomass increase results from the assimilates partitioned to
the root system. Root death is defined as the current root biomass
multiplied by a relative death rate (`RDRRTB`). The latter as a function
of the development stage (`DVS`).
Increase in root depth is a simple linear expansion over time until the
maximum rooting depth (`RDM`) is reached.
**Simulation parameters**
======= ============================================= ======= ============
Name Description Type Unit
======= ============================================= ======= ============
RDI Initial rooting depth SCr cm
RRI Daily increase in rooting depth SCr |cm day-1|
RDMCR Maximum rooting depth of the crop SCR cm
RDMSOL Maximum rooting depth of the soil SSo cm
TDWI Initial total crop dry weight SCr |kg ha-1|
IAIRDU Presence of air ducts in the root (1) or SCr -
not (0)
RDRRTB Relative death rate of roots as a function TCr -
of development stage
======= ============================================= ======= ============
**State variables**
======= ================================================= ==== ============
Name Description Pbl Unit
======= ================================================= ==== ============
RD Current rooting depth Y cm
RDM Maximum attainable rooting depth at the minimum N cm
of the soil and crop maximum rooting depth
WRT Weight of living roots Y |kg ha-1|
DWRT Weight of dead roots N |kg ha-1|
TWRT Total weight of roots Y |kg ha-1|
======= ================================================= ==== ============
**Rate variables**
======= ================================================= ==== ============
Name Description Pbl Unit
======= ================================================= ==== ============
RR Growth rate root depth N cm
GRRT Growth rate root biomass N |kg ha-1 d-1|
DRRT Death rate root biomass N |kg ha-1 d-1|
GWRT Net change in root biomass N |kg ha-1 d-1|
======= ================================================= ==== ============
**Signals send or handled**
None
**External dependencies:**
======= =================================== ================= ============
Name Description Provided by Unit
======= =================================== ================= ============
DVS Crop development stage DVS_Phenology -
DMI Total dry matter CropSimulation |kg ha-1 d-1|
increase
FR Fraction biomass to roots DVS_Partitioning -
======= =================================== ================= ============
"""
"""
IMPORTANT NOTICE
Currently root development is linear and depends only on the fraction of assimilates
send to the roots (FR) and not on the amount of assimilates itself. This means that
roots also grow through the winter when there is no assimilation due to low
temperatures. There has been a discussion to change this behaviour and make root growth
dependent on the assimilates send to the roots: so root growth stops when there are
no assimilates available for growth.
Finally, we decided not to change the root model and keep the original WOFOST approach
because of the following reasons:
- A dry top layer in the soil could create a large drought stress that reduces the
assimilates to zero. In this situation the roots would not grow if dependent on the
assimilates, while water is available in the zone just below the root zone. Therefore
a dependency on the amount of assimilates could create model instability in dry
conditions (e.g. Southern-Mediterranean, etc.).
- Other solutions to alleviate the problem above were explored: only put this limitation
after a certain development stage, putting a dependency on soil moisture levels in the
unrooted soil compartment. All these solutions were found to introduce arbitrary
parameters that have no clear explanation. Therefore all proposed solutions were discarded.
We conclude that our current knowledge on root development is insufficient to propose a
better and more biophysical approach to root development in WOFOST.
"""
[docs] class Parameters(ParamTemplate):
RDI = Float(-99.)
RRI = Float(-99.)
RDMCR = Float(-99.)
RDMSOL = Float(-99.)
TDWI = Float(-99.)
IAIRDU = Float(-99)
RDRRTB = AfgenTrait()
[docs] class RateVariables(RatesTemplate):
RR = Float(-99.)
GRRT = Float(-99.)
DRRT = Float(-99.)
GWRT = Float(-99.)
[docs] class StateVariables(StatesTemplate):
RD = Float(-99.)
RDM = Float(-99.)
WRT = Float(-99.)
DWRT = Float(-99.)
TWRT = Float(-99.)
[docs] def initialize(self, day, kiosk, parvalues):
"""
:param day: start date of the simulation
:param kiosk: variable kiosk of this PCSE instance
:param parvalues: `ParameterProvider` object providing parameters as
key/value pairs
"""
self.params = self.Parameters(parvalues)
self.rates = self.RateVariables(kiosk, publish="DRRT")
self.kiosk = kiosk
# INITIAL STATES
params = self.params
# Initial root depth states
rdmax = max(params.RDI, min(params.RDMCR, params.RDMSOL))
RDM = rdmax
RD = params.RDI
# initial root biomass states
WRT = params.TDWI * self.kiosk.FR
DWRT = 0.
TWRT = WRT + DWRT
self.states = self.StateVariables(kiosk, publish=["RD","WRT", "TWRT"],
RD=RD, RDM=RDM, WRT=WRT, DWRT=DWRT,
TWRT=TWRT)
@prepare_rates
def calc_rates(self, day, drv):
p = self.params
r = self.rates
s = self.states
k = self.kiosk
# Increase in root biomass
r.GRRT = k.FR * k.DMI
r.DRRT = s.WRT * p.RDRRTB(k.DVS)
r.GWRT = r.GRRT - r.DRRT
# Increase in root depth
r.RR = min((s.RDM - s.RD), p.RRI)
# Do not let the roots growth if partioning to the roots
# (variable FR) is zero.
if k.FR == 0.:
r.RR = 0.
@prepare_states
def integrate(self, day, delt=1.0):
rates = self.rates
states = self.states
# Dry weight of living roots
states.WRT += rates.GWRT
# Dry weight of dead roots
states.DWRT += rates.DRRT
# Total weight dry + living roots
states.TWRT = states.WRT + states.DWRT
# New root depth
states.RD += rates.RR
class Simple_Root_Dynamics(SimulationObject):
"""Simple class for linear root growth.
Increase in root depth is a simple linear expansion over time until the
maximum rooting depth (`RDM`) is reached.
**Simulation parameters**
======= ============================================= ======= ============
Name Description Type Unit
======= ============================================= ======= ============
RDI Initial rooting depth SCr cm
RRI Daily increase in rooting depth SCr |cm day-1|
RDMCR Maximum rooting depth of the crop SCR cm
RDMSOL Maximum rooting depth of the soil SSo cm
======= ============================================= ======= ============
**State variables**
======= ================================================= ==== ============
Name Description Pbl Unit
======= ================================================= ==== ============
RD Current rooting depth Y cm
RDM Maximum attainable rooting depth at the minimum N cm
of the soil and crop maximum rooting depth
======= ================================================= ==== ============
**Rate variables**
======= ================================================= ==== ============
Name Description Pbl Unit
======= ================================================= ==== ============
RR Growth rate root depth N cm
======= ================================================= ==== ============
**Signals send or handled**
None
**External dependencies:**
None
"""
class Parameters(ParamTemplate):
"""Traits-based class for storing rooting depth parameters
"""
RDI = Float(-99.)
RRI = Float(-99.)
RDMCR = Float(-99.)
RDMSOL = Float(-99.)
class RateVariables(RatesTemplate):
RR = Float(-99.)
class StateVariables(StatesTemplate):
RD = Float(-99.)
RDM = Float(-99.)
def initialize(self, day, kiosk, parameters):
"""
:param day: start date of the simulation
:param kiosk: variable kiosk of this PCSE instance
:param parameters: ParameterProvider object with key/value pairs
"""
self.params = self.Parameters(parameters)
self.rates = self.RateVariables(kiosk)
self.kiosk = kiosk
# INITIAL STATES
params = self.params
# Initial root depth states
rdmax = max(params.RDI, min(params.RDMCR, params.RDMSOL))
RDM = rdmax
RD = params.RDI
self.states = self.StateVariables(kiosk, publish=["RD"],
RD=RD, RDM=RDM)
@prepare_rates
def calc_rates(self, day, drv):
params = self.params
rates = self.rates
states = self.states
# Increase in root depth
rates.RR = min((states.RDM - states.RD), params.RRI)
@prepare_states
def integrate(self, day, delt=1.0):
rates = self.rates
states = self.states
# New root depth
states.RD += rates.RR