Skip to content

The sim.json configuration file

The sim.json file contains simulation-specific information such as the start and end date (MONICA will select the appropriate climate data from climate.csv) and whether certain global toggles, such as nitrogen response or the use of secondary yields, are turned on or off.

NumberOfLayers and LayerThickness should not be changed at this time.

Reading climate data (climate.csv-options)

Climate data are stored in .csv files. The climate.csv-options object in sim.json configures how they are read. The time range for a MONICA run is defined by the keys start-date and end-date inside the climate.csv-options JSON object. If these keys are not present, the time range is taken directly from climate.csv.

The key no-of-climate-file-header-lines defines how many lines will be skipped at the beginning of the file, as there may be no header (0), only column names (1), or multiple header lines (e.g., including units). The csv-separator key defines which character separates columns and values. In a Comma Separated Values (CSV) file, this is usually a ,, but it could also be a tab \t, space, or another character.

MONICA accepts Available Climate Data (ACD) names for the climate input. These names are case-sensitive.

ACD element Description Example Unit
day Day of year 5
month Month of year 11
year Year 2017
iso-date ISO date format 2017-11-05
de-date German date format 05.11.2017
tmin Minimum daily temperature -2 °C
tavg Average daily temperature 15.3 °C
tmax Maximum daily temperature 34.7 °C
precip Daily precipitation 2.3 mm
globrad Global radiation 27.431 MJ m-2
sunhours Hours of sunshine (better use globrad) 8.5 h
wind Wind speed 6.7 m s-1
relhumid Relative humidity 90.0 %
skip Skip an existing element

Unknown column headers are skipped automatically. The skip ACD can be used explicitly to ignore known elements, for example, if there are multiple columns for the same type of climate variable.

To use any climate dataset without modifying the original file, column names can be mapped to the corresponding ACD names using the header-to-acd-names object. Its key/value pairs define these mappings.

Additionally, the value in this mapping can be a JSON array containing two elements – an arithmetic operation (+, -, *, /) and a number. In that case, the operation is applied to the values in that column. In the example below, if the .csv file contains a column global_radiation in J cm-2, it can be mapped to globrad (MONICA's internal ACD name) and multiplied (*) by 100.0 to convert to MJ m-2.

"climate.csv-options": {
  "__given the start and end date, monica will run just this time range, else the full time range given by supplied climate data": "",
  "start-date": "1991-01-01",
  "end-date": "1997-12-31",

  "no-of-climate-file-header-lines": 1,
  "csv-separator": ",",
  "header-to-acd-names": {
    "DE-date": "de-date",
    "global_radiation": "globrad",
    "global_radiation": ["*", 100.0]
}

Outputting results from MONICA

All results from a MONICA run can be written to a CSV file. Which results are written, and how they are aggregated, is configured in sim.json under the key output.

The following table describes several available options which can be set:

Key Description Example/Default Value
path-to-output Path to directory for output files ./ (current directory)
write-file? Whether to write an output file to "path-to-output" true or false
include-header-row Include header row in the output true or false
include-units-row Include a row with units true or false
include aggregation-rows Include two rows showing a) the expression which requested an output and b) what MONICA interpreted (for debugging purposes) true or false
csv-separator Separator character ,
events A list of pairs, which describe the events on which MONICA is requested to output a list of results

Defining events

The events key defines the list of MONICA results to be written to the output. Each event is specified as a pair, consisting of an event definition followed by the corresponding list of outputs.

Events are defined inside a JSON array and can take one of the following forms:

  • A simple string such as "daily",
  • A JSON array, or
  • A full JSON object that explicitly describes the conditions under which outputs should be generated.

Strings and JSON arrays serve as shortcuts for more complex JSON objects that describe the triggering conditions for generating output.

The event structure allows specification of:

  1. When to start and end outputting results (start and end keys)
  2. Time ranges to aggregate results (from and to keys)
  3. Points at which time or condition to write results (non-aggregated)
  4. Periods while conditions are true (for conditional aggregation)

ISO dates can include placeholders (x). Every possible value for the year, month, or day of the placeholder is used. For example, xxxx-xx-15 means every 15th day of each month.

Available events

In addition to date patterns, each workstep generates an event with the same name (e.g., Sowing, Harvest, AutomaticSowing, SetValue, etc.).

Common events include:

  • run-started
  • Stage-1, Stage-2, ...
  • emergence
  • anthesis
  • cereal-stem-elongation
  • maturity
  • Sowing, AutomaticSowing, Cutting, etc.

The following table shows examples of some event expressions, their shortcut forms, and their expanded equivalents:

Shortcut Expanded form Meaning
{"start": "xxxx-05-01", "end": "xxxx-07-31", "at": "xxxx-xx-15"} Output results on the 15th of each month from May to July – daily results will be written
{"from": "Sowing", "to": "anthesis", "while": ["ETa/ETc", "<", 0.4]} Output aggregated results from the Sowing event until (and including) the anthesis event, but only while actual to potential evapotranspiration is below 0.4
"xxxx-03-31" {"at": "xxxx-03-31"} Write results every March 31st
"daily" {"at": "xxxx-xx-xx"} Write daily results
"monthly" {"from": "xxxx-xx-01", "to": "xxxx-xx-31"} Write monthly aggregated results
"yearly" {"from": "xxxx-01-01", "to": "xxxx-12-31"} Write yearly aggregated results
"run" {"from": <start-date>, "to": <end-date>} Write results aggregated over the entire simulation run
"crop" {"from": "Sowing", "to": "Harvest"} Write results aggregated over the cropping period
["while", "Stage", "=", 5] {"while": ["Stage", "=", 5]} Write results aggregated only while Stage equals 5
["at", "Stage", "=", 2] {"at": ["Stage", "=", 2]} Write results daily when Stage equals 2
[["Mois", 1], "<", 0.5] {"at": ["Mois", 1], "<", 0.5]} Write results daily when the soil moisture in the first layer is below 0.5
"Sowing" {"at": "Sowing"} Write results at sowing time

As shown in the table above, simple comparison expressions can be used in events. The available operators are <, <=, =, >=, >. Output expressions such as "Stage" or ["Mois", 1], as well as numeric values (e.g., 1), can be used on both sides of these operators.

List of outputs

After defining events (i.e., when to output), you must specify what to output. Some examples of outputs already appeared in the previous table, such as ["at", "Stage", "=", 2] or [["Mois", 1], "<", 0.5]. "Stage" outputs the current development stage of the plant, while ["Mois", 1] outputs the soil moisture in the first 10 cm soil layer.

MONICA supports three categories of outputs:

  1. Scalar values (e.g., "Stage")
  2. Array values for soil layers (e.g., "Mois", which consists of 20 values representing soil moisture in all layers)
  3. Array values for crop organs (e.g., ["OrgBiom", "Root"])

MONICA currently uses 20 soil layers of 10 cm each (total depth 2 m). When outputs refer to layers, they can specify:

  • a single layer (e.g., 15 for the 15th layer, corresponding to 1.5 m depth),
  • a range of layers (e.g., [1, 5] for layers 1 to 5, corresponding to 0 to 0.5 m depth),
  • or a crop organ (e.g., "Root", "Leaf", "Shoot", "Fruit", "Struct", "Sugar").

Additionally, the user must tell MONICA whether ranges of values (in arrays) should be output as multiple scalars or aggregated into a single value. If aggregation is applied, the aggregation method must also be specified.

The available aggregation operations are: AVG, MEDIAN, SUM, MIN, MAX, FIRST, LAST, NONE.

Aggregation can occur on a daily basis to aggregate soil layers into a single scalar value (the default operation for layer aggregation is NONE) or over a time range, e.g. to aggregate monthly values, where the default operation in this case is AVG.

Aggregation reason Default operation Meaning
Aggregate soil layers into scalar value NONE If no aggregation operation is specified, the selected range of layer values will be output as individual values.
Aggregate time range AVG If an event defines an aggregation time range and no aggregation operation is specified (value 2 or 3 in the JSON array), the temporarily collected daily values will be averaged.

To understand aggregation operations, imagine that all values to be aggregated (e.g., Runoff) are stored temporarily in a list during the from/to period . After the to time range ends, the specified aggregation operation is applied to this list. For example, AVG will calculate the mean of all values, while FIRST will return the first value in the list – the value from the start (from day) of the aggregation period.

The user specifies an output either by simply defining the output name (e.g., "Stage", "Crop", or "Date") or by using a JSON array, where the first element of the array is the aforementioned output name. It is also possible to append a display name to the output name, separated by the character |. This display name will be used in the output instead of the result name. For example, "DOY|MatDOY" will output MatDOY instead of DOY, which may be more descriptive.

The second element in the array can specify one of the following:

  • the selected soil layer,
  • a range of layers,
  • a crop organ (for array values), or
  • an aggregation operation (for scalar values).

If omitted, the aggregation operation defaults to NONE.

For array outputs, a third element can define the aggregation operation. The second element can be:

  • a single number (e.g., the soil layer number),
  • a string describing the crop organ, or
  • an array that describes a layer range (for soil layers only).

In the latter case, the first value of the array is the starting layer, the second the ending layer (inclusive), and an optional third value specifies the aggregation operation. If the range includes an aggregation operation, MONICA will apply it and store a single aggregated value each time output is requested. Otherwise, individual layer values will be listed in the output, each labeled with the result name and the corresponding layer number (e.g., Mois_1, Mois_2, etc.).

The following examples show the possible variations:

Output definition Meaning
"Date" Output the ISO date (e.g., 2017-01-17)
["Year", "LAST"] Output the year at the to time – the year at the end of the aggregation period
["PercolationRate\|WDrain", 15, "SUM"] Output the sum of percolation rates in soil layer 15 (1.5 m) during the aggregation period, and rename it in the output as WDrain (SUM requires an event to specify the aggregation time range.)
["Mois", [1, 20]] Output the daily soil moisture of all 20 soil layers. The outputs will be labeled "Mois_1", "Mois_2", etc.
["OrgBiom", "Leaf"] Output the daily organic biomass of leaves
["SOC", [1, 3, "AVG"]] Output the daily soil organic carbon as a single value averaged across the first three soil layers
["Precip", "SUM"] Output the sum of precipitation values within a given aggregation time range

In the generated output file, the order of the results follows the sequence defined in the events list and can be relied upon.

The example below shows an output section that produces an equivalent file to the rmout file from MONICA version 1. It also includes a commented out (__events) example of outputs used in the EU MACSUR Heat Stress study.

"output": {
  "write-file?": false,
  "file-name": "out.csv",

  "csv-options": {
    "include-header-row": true,
    "include-units-row": true,
    "include-aggregation-rows": true,
    "csv-separator": ","
  },

  "__events": [
    "crop", [
      ["Year", "LAST"],
      ["DOY|SowDOY", "FIRST"],
      ["LAI|MaxLAI", "MAX"],
      ["PercolationRate|WDrain", 15, "SUM"],
      ["Act_ET|CumET", "SUM"],
      ["Act_Ev|Evap", "SUM"],
      ["Mois|SoilAvW", [1, 15, "SUM"], "LAST"],
      ["Runoff", "SUM"],
      ["ET0|Eto", "SUM"],
      ["Tmax|TMAXAve", "AVG"],

      ["Yield", "LAST"],
      ["AbBiom|Biom-ma", "LAST"],
      ["AbBiomN|CroN-ma", "LAST"],
      ["GrainN", "LAST"]
    ],

    ["while", "Stage", "=", 5], [
      ["DOY|AntDOY", "FIRST"],
      ["AbBiom|Biom-an", "First"],
      ["AbBiomN|CroN-an", "FIRST"]
    ],

    ["while", "Stage", "=", 7], [
      ["Yield", "FIRST"],
      ["DOY|MatDOY", "FIRST"],
      ["AbBiom|Biom-ma", "First"],
      ["AbBiomN|CroN-ma", "FIRST"],
      ["GrainN", "FIRST"]
    ],

    ["while", "Stage", "=", 2], [
      ["DOY|EmergDOY", "FIRST"]
    ]
  ],

  "events" : [
    "daily", [
      "Date", "Crop", "TraDef", "Tra", "NDef", "HeatRed", "FrostRed", "OxRed",
      "Stage", "TempSum", "VernF", "DaylF",
      "IncRoot", "IncLeaf", "IncShoot", "IncFruit",
      "RelDev", "LT50", "AbBiom",
      ["OrgBiom", "Root"], ["OrgBiom", "Leaf"], ["OrgBiom", "Shoot"],
      ["OrgBiom", "Fruit"], ["OrgBiom", "Struct"], ["OrgBiom", "Sugar"],
      "Yield", "SumYield", "GroPhot", "NetPhot", "MaintR", "GrowthR",   "StomRes",
      "Height", "LAI", "RootDep", "EffRootDep", "TotBiomN", "AbBiomN", "SumNUp",
      "ActNup", "PotNup", "NFixed", "Target", "CritN", "AbBiomNc", "YieldNc",
      "Protein",
      "NPP", ["NPP", "Root"], ["NPP", "Leaf"], ["NPP", "Shoot"],
      ["NPP", "Fruit"], ["NPP", "Struct"], ["NPP", "Sugar"],
      "GPP",
      "Ra",
      ["Ra", "Root"], ["Ra", "Leaf"], ["Ra", "Shoot"], ["Ra", "Fruit"],
      ["Ra", "Struct"], ["Ra", "Sugar"],
      ["Mois", [1, 20]], "Precip", "Irrig", "Infilt", "Surface", "RunOff", "SnowD", "FrostD",
      "ThawD", ["PASW", [1, 20]], "SurfTemp", ["STemp", [1, 5]],
      "Act_Ev", "Act_ET", "ET0", "Kc", "AtmCO2", "Groundw", "Recharge", "NLeach",
      ["NO3", [1, 20]], ["Carb", 0], ["NH4", [1, 20]], ["NO2", [1, 4]],
      ["SOC", [1, 6]], ["SOC-X-Y", [1, 3, "SUM"]], ["SOC-X-Y", [1, 20, "SUM"]],
      ["AOMf", 1], ["AOMs", 1], ["SMBf", 1], ["SMBs", 1], ["SOMf", 1],
      ["SOMs", 1], ["CBal", 1], ["Nmin", [1, 3]], "NetNmin", "Denit", "N2O", "SoilpH",
      "NEP", "NEE", "Rh", "Tmin", "Tavg", "Tmax", "Wind", "Globrad", "Relhumid", "Sunhours",
      "NFert"
    ]
  ]
}

Below you will find a simplified example of a complete sim.json file focused on output configuration.

{
  "climate.csv-options": {
        "__given the start and end date, monica will run just this time range, else the full time range given by supplied climate data": "",
        "start-date": "1991-01-01",
        "end-date": "1997-12-31",

        "no-of-climate-file-header-lines": 1,
        "csv-separator": ",",
        "header-to-acd-names": {
            "DE-date": "de-date"
        }
    },

  "output": {
      "write-file?": false,
        "file-name": "out.csv",

        "__how to write and what to include in monica CSV output": "",
        "csv-options": {
            "include-header-row": true,
            "include-units-row": true,
            "include-aggregation-rows": true,
            "csv-separator": ","
        },

        "__what data to include in the monica output according to the events defined by the keys": "",
        "events" : [
            "monthly", [
                "Year", "Month",
                ["SOC", [1, 1, "AVG"]], ["SOC", [1, 3, "AVG"]],
                ["WaterContent", [1, 9, "AVG"]], "Recharge", "NLeach",
                ["SnowD", "MAX"], ["SnowD", "SUM"], ["FrostD", "SUM"],
                ["RunOff", "SUM"], ["NH3", "SUM"], ["Precip", "SUM"], "Act_ET"
            ],

            "yearly", [
                "Year",
                ["N", [1, 3]],
                ["RunOff", "SUM"],
                ["NLeach", "SUM"],
                ["Recharge", "SUM"]
            ],

            "run", [["Precip", "SUM"]],

            "harvesting", ["Crop", ["OrgBiom", "Fruit"], "Yield"],
        ]
    },

  "NumberOfLayers": 20,
  "LayerThickness": [0.1, "m"],

  "UseSecondaryYields": true,
  "NitrogenResponseOn": true,
  "WaterDeficitResponseOn": true,
  "EmergenceMoistureControlOn": true,
  "EmergenceFloodingControlOn": true,
  "FrostKillOn": true,

  "UseAutomaticIrrigation": false,
  "AutoIrrigationParams": {
    "irrigationParameters": {
      "nitrateConcentration": [0, "mg dm-3"],
      "sulfateConcentration": [0, "mg dm-3"]
    },
    "amount": [17, "mm"],
    "threshold": 0.35
  },

  "UseNMinMineralFertilisingMethod": false,
  "NMinUserParams": { "min": 0, "max": 0, "delayInDays": 0 },
  "NMinFertiliserPartition": {
    "id": "my AN",
    "name": "my very own ammonium nitrate variant",
    "Carbamid": 0,
    "NH4": 0,
    "NO3": 0
  }
}

Allowed output variables

The most up-to-date list of available and allowed output names can be found directly in the MONICA source code, in the file build-output.cpp. There, you will find entries such as:

build({id++, "Date", "", "output current date"},
...
build({id++, "TraDef", "0;1", "TranspirationDeficit"},

In this example, Date and TraDef are allowed output names. Additionally, the code lists the expected units of measure (if defined) and provides a description for each output variable.

Output name (L)ayers/(O)rgans Setttable? Unit Description
Count Output constant value 1 (can be used for counting records or events)
CM-count Order number of the current cultivation method
Date Current date
days-since-start Number of days since simulation start
DOY Current day of year
Month Current month number (1-12)
Year Current year
Crop Crop name
TraDef 0;1 Transpiration deficit index (1= no stress, 0 = maximum stress)
Tra mm Actual transpiration
NDef 0;1 Nitrogen deficit index, indicates N availability (1 = no stress, 0 = no N available)
HeatRed 0;1 Heat stress reductor
FrostRed 0;1 Frost stress reductor
OxRed 0;1 Oxygen deficit reductor
Stage Phenological development stage
TempSum °Cd Accumulated temperature sum
VernF 0;1 Vernalisation factor
DaylF 0;1 Daylength factor
IncRoot kg ha-1 Growth increment of root
IncLeaf kg ha-1 Growth increment of leaf
IncShoot kg ha-1 Growth increment of shoot
IncFruit kg ha-1 Growth increment of fruit
RelDev 0;1 Relative total development
LT50 °C Crop's lethal temperature at which 50% of plants die
AbBiom kg ha-1 Aboveground biomass
OrgBiom O kgDM ha-1 Biomass of individual crop organs (e.g, Root, Leaf, Shoot, Fruit)
Yield kgDM ha-1 Primary harvested yield
sumExportedCutBiomass kgDM ha-1 Total exported biomass across all cuts for the current crop
exportedCutBiomass kgDM ha-1 Exported biomass from the current crop at the current cut
sumResidueCutBiomass kgDM ha-1 Total residue biomass across all cuts for the current crop
residueCutBiomass kgDM ha-1 Residue biomass from the current crop at the current cut
GroPho kgCH2O ha-1 Gross photosynthesis rate per hectare
NetPhot kgCH2O ha-1 Net photosynthesis per hectare
MaintR kgCH2O ha-1 Maintenance respiration rate per hectare (from AGROSIM)
GrowthR kgCH2O ha-1 Growth respiration rate per hectare (from AGROSIM)
StomRes s m-1 Stomata resistance
Height m Crop height
LAI m2 m-2 Leaf Area Index
RootDep layer# Rooting depth
EffRootDep m Depth of the maximum active and effective root
TotBiomN kgN ha-1 Total nitrogen content in biomass
AbBiomN kgN ha-1 Aboveground nitrogen content in biomass
SumNUp kgN ha-1 Cumulative actual nitrogen uptake by the crop
ActNup kgN ha-1 Actual nitrogen uptake
PotNup kgN ha-1 Potential nitrogen uptake
NFixed kgN ha-1 Nitrogen input by the crop via atmospheric fixation
Target kgN ha-1 Target nitrogen concentration
CritN kgN ha-1 Critical nitrogen concentration
AbBiomNc kgN ha-1 (kg ha-1)-1 Nitrogen concentration in aboveground biomass
Nstress - Nitrogen stress index, indicates N availability (1 = no stress, 0 = no N available)
YieldNc kgN ha-1 Nitrogen concentration in primary yield
Protein kg kg-1 Raw protein concentration
NPP kgC ha-1 Net Primary Production (NPP)
NPP-Organs O kgC ha-1 Organ-specific Net Primary Production (NPP)
GPP kgC ha-1 Gross Primary Production (GPP)
Ra kgC ha-1 Autotrophic respiration
Ra-Organs O kgC ha-1 Organ-specific autotrophic respiration
Mois L x m3 m-3 Soil moisture content per layer
Irrig mm Irrigation amount applied
Infilt mm Amount of water that infiltrates into top soil layer
Surface mm Surface water storage
RunOff mm Surface water runoff for the current day
SnowD mm Snow depth
FrostD m Frost front depth in soil
ThawD m Thaw front depth in soil
PASW L m3 m-3 Plant available soil water per layer
SurfTemp °C Soil surface temperature
STemp L °C Soil temperature by layer
Act_Ev mm Actual evaporation
Pot_ET mm Potential evapotranspiration = ET0 * Kc = the plants water use
Act_ET mm Actual evapotranspiration = actual transpiration + actual evaporation + evaporation from interception + evaporation from surface
ET0 mm Reference evapotranspiration
Kc Plant coefficient to calculate with ET0 the plants water use (ET0 * Kc)
AtmCO2 ppm Atmospheric CO2 concentration in the atmosphere
Groundw m Groundwater table depth
Recharge mm Groundwater recharge
NLeach kgN ha-1 Nitrogen leaching below the root zone
NO3 L x kgN m-3 Soil nitrate (NO3) per layer
Carb L x kgN m-3 Soil carbamide per layer
NH4 L x kgN m-3 Soil ammonium (NH4) per layer
NO2 L x kgN m-3 Soil nitrite (NO2) per layer
SOC L kgC kg-1 Soil organic carbon content per layer
SOC-X-Y L gC m-2 Soil organic carbon stock between soil layers X and Y. (SOC * bulk density * layer thickness * 1000)
AOMf L kgC m-3 Sum of added organic matter (AOM) fast pool carbon content
AOMs L kgC m-3 Sum of added organic matter (AOM) slow pool carbon content
SMBf L kgC m-3 Soil microbial biomass (SMB) fast pool carbon content
SMBs L kgC m-3 Soil microbial biomass (SMB) slow pool carbon content
SOMf L kgC m-3 Soil organic matter (SOM) fast pool carbon content
SOMs L kgC m-3 Soil organic matter (SOM) slow pool carbon content
CBal L kgC m-3 Carbon balance per layer
Nmin L kgN ha-1 Net nitrogen mineralisation rate per layer
NetNmin kgN ha-1 Net nitrogen mineralisation rate for the layers defined in the parameter MaxMineralizationDepth (see general/soil-organic.json)
Denit kgN ha-1 Amount of N resulting from denitrification
actnitrate kgN m-3 N production rate resulting from nitrification (N2O STICS module)
N2O kgN ha-1 Total N2O produced (MONICA's original approach)
N2Onit kgN ha-1 N2O produced through nitrification (N2O STICS module)
N2Odenit kgN ha-1 N2O produced through denitrification (N2O STICS module)
SoilpH Soil pH
NEP kgC ha-1 Net Ecosystem Production (NEP)
NEE kgC ha- Net Ecosystem Exchange (NEE)
Rh kgC ha- Daily decomposer respiration
Tmin °C Minimum daily air temperature
Tavg °C Mean daily air temperature
Tmax °C Maximum daily air temperature
Precip mm Precipitation
Wind m s-1 Wind speed
Globrad MJ m-2 Global radiation
Relhumid % Relative humidity
Sunhours h Sunshine duration
BedGrad 0;1 Fractional soil coverage
N L kgN m-3 Mineral nitrogen content in soil
Co L kgC m-3 Soil organic carbon concentration per soil layer
NH3 kgN ha-1 Ammonia (NH3) volatilisation
NFert kgN ha-1 Daily nitrogen fertiliser input
WaterContent L fraction nFC Fraction of usable field capacity: PASW/(FC-PWP)
CapillaryRise L mm Capillary rise
PercolationRate L mm Percolation rate
SMB-CO2-ER L Soil microbial biomass (SMB) CO2 evolution rate
Evapotranspiration mm Remaining evapotranspiration after evaporation of intercepted water
Evaporation mm Evaporation from intercepted water
ETa/ETc Ratio of actual to potential evapotranspiration Act_ET/Pot_ET (actual evapotranspiration/potential evapotranspiration)
Transpiration mm Actual transpiration
GrainN kg ha-1 Nitrogen content of harvested grains
Fc L m3 m-3 Field capacity
Pwp L m3 m-3 Permanent wilting point
Nresid kgN ha-1 Nitrogen content in crop residues
Sand L kg kg-1 Soil sand content
Clay L kg kg-1 Soil clay content
Silt L kg kg-1 Soil silt content
Stone L kg kg-1 Soil stone content
pH L kg kg-1 Soil pH per layer
rootDensity L Root density in soil layer
rootingZone Current rooting zone, the soil layer into which roots are growing

Automatic irrigation trigger

Automatic irrigation can be enabled or disabled using the UseAutomaticIrrigation key (set to true or false). If the key amount is defined, a fixed amount of irrigation water will be applied. Alternatively, if set_to_%nFC is specified, the soil moisture of the affected layers (up to the depth defined by calc_nFC_until_depth_m) will be set to the given percentage of available soil water. The trigger becomes active only when a crop is currently growing and MONICA's internal current temperature sum is between HeatSumIrrigationStart and HeatSumIrrigationEnd. Both parameters are defined in the cultivar JSON file of the active crop.

Key Default value Unit Description
"UseAutomaticIrrigation" true or false Enables or disables automatic irrigation
"nitrateConcentration" 0 mg dm-3 Nitrate concentration in irrigation water
"sulfateConcentration" 0 mg dm-3 Sulfate concentration in irrigation water (currently ignored by MONICA)
"amount" mm Amount of irrigation water to apply when plant available water drops below the trigger threshold
"set_to_%nFC" % nFC Sets soil moisture of the involved layers to the specified percentage of plant available water (nFC)
"threshold" fraction nFC Fraction of net field capacity (plant available water = field capacity - permanent wilting point to) that must be reached before irrigation is triggered
⚠️ Deprecated, use trigger_if_nFC_below_% instead.
"trigger_if_nFC_below_%" % nFC Triggers irrigation if the percentage of net field capacity (plant available water = field capacity - permanent wilting point to) drops below this value
"calc_nFC_until_depth_m" 0.3 m The soil depth used by MONICA to check whether the irrigation trigger condition is met

Example 1:

Apply 17 mm irrigation each time the plant available water in the first 30 cm of the soil profile drops below 50%.

"UseAutomaticIrrigation": false,
"AutoIrrigationParams": {
  "amount": [17, "mm"],
  "trigger_if_nFC_below_%": [50, "%"],
  "calc_nFC_until_depth_m": [0.3, "m"]
}

Example 2:

Set soil moisture in the first 50 cm of the soil profile to field capacity = 100% nFC, if the plant available water drops below 50%. This time add 10 mg dm-3 of nitrate with the irrigation water.

"UseAutomaticIrrigation": false,
"AutoIrrigationParams": {
  "irrigationParameters": {
    "nitrateConcentration": [10, "mg dm-3"],
  },
  "trigger_if_nFC_below_%": [50, "%"],
  "set_to_%nFC": [100, "%"],
  "calc_nFC_until_depth_m": [0.5, "m"]
}