climag.modvege#
modvege.py
- climag.modvege.sum_of_temperature_thresholds(timeseries, params) dict[str, float]#
Calculate sum of temperatures
Parameters#
- timeseriespandas.DataFrame
Input meteorological time series data
- paramsdict
A dictionary of input parameters
Returns#
- dict[str, float]
Dictionary of the sum of temperature thresholds
Notes#
- Calculate sum of temperatures at:
the beginning of the reproductive period (ST₁) [°C d]
the end of the reproductive period (ST₂) [°C d]
the beginning of the grazing season (STg₁) [°C d]
the end of the grazing season (STg₂) [°C d]
the beginning of harvest (STh₁) [°C d]
Nolan and Flanagan (2020) define the thermal growing season length as the number of days between the first occurrence of at least six consecutive days with a daily mean temperature of > 5°C and the first occurrence of at least six consecutive days with a daily mean temperature of < 5°C.
If the temperatures are too low (i.e. no six consecutive days > 5°C) to calculate the start date of the growing season, assume it is the 15th March, which is the median date for the midlands and part of northern Ireland (Collins and Cummins, 1996; Connaughton, 1973). This is also the date when cows are out full time according to Teagasc recommendations (Kavanagh, 2016).
Calculating the end date of the growing season is not straightforward, as the temperatues may be too high for there to be six consecutive days < 5°C, or these six consecutive days may happen very early in the year, and may even be before the growing season start date.
Grazing season calculations based solely on temperature do not consider the delay before sufficient plant cover is available to support grazing animals or the ability of animals and machinery to pass over land (Nolan and Flanagan, 2020; Collins and Cummins, 1996; based on Keane, 1982).
The beginning of the grazing season has a delay of 5-15 days after the start of the growing season based on Broad and Hough (1993). A delay of 10 days is used to allow sufficient reproductive growth. ~The end date of the grazing season is determined using the Smith formula for calculating the grazing season length (Collins and Cummins, 1996; based on Smith, 1976).~
The end date of the grazing season cannot exceed 1st December. Livestock are assumed to be fully housed by 22nd November based on Teagasc recommendations (Kavanagh, 2016). The mean latest autumn closing date is 3rd December, with a two-week interval of 26th November to 9th December (Looney et al., 2021).
Grazing will only take place if there is sufficient biomass available; if the residual biomass has a height of less than 5 cm, no grazing or harvesting will take place. Therefore, the amount of ingested and harvested biomass are mainly influenced by the environmental factors that affect growth, such as temperature, radiation, and precipitation.
The beginning of harvest is assumed to be one day before the grazing season ends. Grazing costs less than indoor feeding, so starting the harvest just a day before the end of the grazing season ensures grazing is maximised. The end of harvest is the same as the end of the grazing season.
- climag.modvege.modvege(params, tseries, endday=365, t_init=None) dict[str, float]#
ModVege model as a function
Parameters#
- paramsdict
Parameters (constants)
- tseriespandas.DataFrame
Time series meteorological data
- enddayint
Number of days of the year (default is 365)
Returns#
- dict[str, float]
Dictionary of results
Notes#
- Results:
Green vegetative biomass [kg DM ha⁻¹]
Dead vegetative biomass [kg DM ha⁻¹]
Green reproductive biomass [kg DM ha⁻¹]
Dead reproductive biomass [kg DM ha⁻¹]
Total standing biomass [kg DM ha⁻¹]
Potential growth [kg DM ha⁻¹]
Total growth [kg DM ha⁻¹]
Ingested biomass [kg DM ha⁻¹]
Harvested biomass [kg DM ha⁻¹]
Leaf area index [dimensionless]
Water reserves [mm]
Actual evapotranspiration [mm]
Environmental limitation of growth [dimensionless]
Reproductive function [dimensionless]