Species-level crop parameters
This section describes the JSON properties used to configure species-level crop parameters in MONICA.
Species parameters describe characteristics shared by all cultivars of a species. Cultivar-specific properties are defined separately.
JSON conventions
Numbermeans a JSON number and may contain either an integer or a decimal value.Integermeans a whole-number JSON value.- Stage-dependent arrays must use the same stage order and normally have the same length as
BaseTemperature. -
Organ-dependent arrays use this order:
1. root 2. leaf 3. stem or shoot 4. storage organ, such as fruit, grain, or ear -
Missing properties are not necessarily reported as errors. Depending on the property, MONICA may retain a default value. Arrays required by an enabled model component must nevertheless contain the expected number of entries.
General and physiological parameters
| Parameter name | Type | Unit | Description | Example |
|---|---|---|---|---|
type |
String | Serialization metadata identifying the object as species parameters | "type": "SpeciesParameters" |
|
SpeciesName |
String | Identifier or name of the crop species | "SpeciesName": "wheat" |
|
CarboxylationPathway |
Integer | Photosynthetic pathway type: 1 = C3, 2 = C4 |
"CarboxylationPathway": 1 |
|
DefaultRadiationUseEfficiency |
Number | g MJ-1 | Default radiation-use-efficiency coefficient used by the crop photosynthesis calculation | "DefaultRadiationUseEfficiency": 0.5 |
MinimumTemperatureForAssimilation |
Number | °C | Lower temperature threshold for photosynthetic assimilation | "MinimumTemperatureForAssimilation": 4 |
OptimumTemperatureForAssimilation |
Number | °C | Optimum temperature for photosynthetic assimilation | "OptimumTemperatureForAssimilation": 27 |
MaximumTemperatureForAssimilation |
Number | °C | Upper temperature threshold for photosynthetic assimilation | "MaximumTemperatureForAssimilation": 35 |
InitialKcFactor |
Number | Crop coefficient at the beginning of crop development | "InitialKcFactor": 0.4 |
|
FieldConditionModifier |
Number | Multiplier applied to assimilate production to represent unspecified field limitations. A value of 1 applies no reduction. |
"FieldConditionModifier": 1 |
|
AssimilateReallocation |
Number | Fraction of senescing organ biomass that can be reallocated to the storage organ | "AssimilateReallocation": 0.3 |
|
DevelopmentAccelerationByNitrogenStress |
Integer | Switch controlling whether nitrogen stress accelerates crop development: normally 0 = disabled and 1 = enabled |
"DevelopmentAccelerationByNitrogenStress": 1 |
|
DroughtImpactOnFertilityFactor |
Number | Controls the reduction in reproductive fertility caused by severe drought. A value of 0 disables this response. |
"DroughtImpactOnFertilityFactor": 0 |
|
LimitingTemperatureHeatStress |
Number | °C | Limiting temperature used by the crop heat-stress response | "LimitingTemperatureHeatStress": 40 |
CuttingDelayDays |
Integer | d | Number of days for which crop development or growth is delayed after cutting | "CuttingDelayDays": 0 |
Development-stage parameters
| Parameter name | Type | Unit | Description | Example |
|---|---|---|---|---|
BaseTemperature |
Number (Array) | °C | Base temperature for thermal-time accumulation in each developmental stage. The array length defines the number of developmental stages. | "BaseTemperature": [0, 1, 1, 1, 9, 9] |
CriticalOxygenContent |
Number (Array) | m3 m-3 | Critical soil oxygen content for each developmental stage | "CriticalOxygenContent": [0.08, 0.08, 0.08, 0.08, 0.08, 0.08] |
StageMaxRootNConcentration |
Number (Array) | kg N kg-1 DM | Maximum root nitrogen concentration in each developmental stage | "StageMaxRootNConcentration": [0.02, 0.02, 0.012, 0.01, 0.01, 0.01] |
StageMobilFromStorageCoeff |
Number (Array) | fraction | Stage-specific coefficient controlling mobilization of biomass from the storage organ. If omitted, MONICA initializes one zero for each entry in CriticalOxygenContent. |
"StageMobilFromStorageCoeff": [0, 0, 0, 0, 0, 0] |
StageAtMaxHeight |
Number | stage | Developmental stage at which the crop reaches its maximum height. Normally specified as a whole stage number. | "StageAtMaxHeight": 3 |
StageAtMaxDiameter |
Number | stage | Stage at which maximum crop diameter is reached. Currently has no effect on subsequent model calculations. | "StageAtMaxDiameter": 2 |
StageAfterCut |
Integer | stage | Developmental stage to which the crop is reset after cutting. MONICA converts this value to its zero-based internal stage index by subtracting one. Use 0 only for species that are never cut. |
"StageAfterCut": 0 |
TransitionStageLeafExp |
Integer | stage | Stage through which the early-stage temperature response for leaf expansion is used. -1 disables the transition. |
"TransitionStageLeafExp": -1 |
Organ parameters
Organ arrays use the order root, leaf, stem/shoot, and storage organ.
| Parameter name | Type | Unit | Description | Example |
|---|---|---|---|---|
AbovegroundOrgan |
Boolean (Array) | Indicates whether each organ contributes to aboveground biomass | "AbovegroundOrgan": [false, true, true, true] |
|
StorageOrgan |
Boolean (Array) | Indicates which organ is treated as the crop's storage organ | "StorageOrgan": [false, false, false, true] |
|
InitialOrganBiomass |
Number (Array) | kg DM ha-1 | Initial dry-matter biomass of each organ at crop establishment | "InitialOrganBiomass": [53, 53, 0, 0] |
OrganGrowthRespiration |
Number (Array) | fraction | Organ-specific fraction of allocated assimilates consumed by growth respiration | "OrganGrowthRespiration": [0.306, 0.315, 0.338, 0.291] |
OrganMaintenanceRespiration |
Number (Array) | d-1 | Organ-specific maintenance-respiration coefficient | "OrganMaintenanceRespiration": [0.01, 0.03, 0.015, 0.01] |
MaxCropDiameter |
Number | m | Maximum crop diameter. Currently affects only an internal green-area-index variable that is not used by subsequent model calculations. | "MaxCropDiameter": 0.005 |
PlantDensity |
Integer | plants m-2 | Number of plants per square meter. Currently has no effect on subsequent model calculations. | "PlantDensity": 220 |
Nitrogen parameters
| Parameter name | Type | Unit | Description | Example |
|---|---|---|---|---|
MinimumNConcentration |
Number | kg N kg-1 DM | Minimum nitrogen concentration in aboveground biomass before maximum nitrogen stress is reached | "MinimumNConcentration": 0.005 |
NConcentrationAbovegroundBiomass |
Number | kg N kg-1 DM | Initial nitrogen concentration in aboveground biomass | "NConcentrationAbovegroundBiomass": 0.06 |
NConcentrationRoot |
Number | kg N kg-1 DM | Initial nitrogen concentration in root biomass | "NConcentrationRoot": 0.02 |
NConcentrationB0 |
Number | Coefficient controlling the biomass-dependent curvature of the critical nitrogen-concentration function | "NConcentrationB0": 2 |
|
NConcentrationPN |
Number | Scaling parameter of the critical nitrogen-concentration function | "NConcentrationPN": 1.6 |
|
LuxuryNCoeff |
Number | Multiplier defining nitrogen uptake above the critical nitrogen requirement | "LuxuryNCoeff": 1.3 |
|
PartBiologicalNFixation |
Number | fraction | Fraction of crop nitrogen demand that can be supplied by biological nitrogen fixation | "PartBiologicalNFixation": 0 |
MaxNUptakeParam |
Number | kg N m-1 root d-1 | Parameter used to limit daily nitrogen uptake as a function of total root length and crop development | "MaxNUptakeParam": 3.145 |
SamplingDepth |
Number | m | Soil depth over which mineral nitrogen is evaluated by the automatic Nmin fertilization method | "SamplingDepth": 0.9 |
TargetN30 |
Number | kg N ha-1 | Target amount of available mineral nitrogen in the upper 0.30 m of the soil | "TargetN30": 120 |
TargetNSamplingDepth |
Number | kg N ha-1 | Target amount of available mineral nitrogen from the soil surface down to SamplingDepth |
"TargetNSamplingDepth": 230 |
Root parameters
| Parameter name | Type | Unit | Description | Example |
|---|---|---|---|---|
InitialRootingDepth |
Number | m | Rooting depth at crop establishment | "InitialRootingDepth": 0.1 |
MinimumTemperatureRootGrowth |
Number | °C | Minimum temperature for active root growth | "MinimumTemperatureRootGrowth": 0 |
RootGrowthLag |
Number | °C d | Thermal-time threshold or offset controlling the beginning of rooting-depth growth. Negative values are permitted. | "RootGrowthLag": -30 |
RootPenetrationRate |
Number | m (°C d)-1 | Increase in rooting depth per accumulated degree-day | "RootPenetrationRate": 0.0011 |
RootDistributionParam |
Number | Legacy root-distribution parameter. Its former calculation is currently commented out. Root distribution is controlled by RootFormFactor. |
"RootDistributionParam": 0.002787 |
|
RootFormFactor |
Number | m-1 | Exponential shape coefficient used to distribute root density over soil depth | "RootFormFactor": 3 |
SpecificRootLength |
Number | m g-1 DM | Root length per unit root dry-matter biomass. It is used to calculate total root length from root biomass. | "SpecificRootLength": 300 |
Perennial-crop dormancy parameters
| Parameter name | Type | Unit | Description | Example |
|---|---|---|---|---|
DormancyStartDoy |
Integer | day of year | Day of year on which dormancy begins for a perennial crop. 0 means unset. |
"DormancyStartDoy": 0 |
DormancyEndDoy |
Integer | day of year | Day of year on which dormancy ends and thermal-time accumulation resumes. 0 means unset. |
"DormancyEndDoy": 0 |
Example species parameter object
The following is a structurally complete illustrative wheat parameter object. Parameter values should be calibrated for the intended cultivar, environment, and model configuration. The example should not be treated as a universally recommended wheat parameterization.
{
"SpeciesName":"wheat",
"AbovegroundOrgan":[
false,
true,
true,
true
],
"AssimilateReallocation":0.3,
"BaseTemperature":[
0,
1,
1,
1,
9,
9
],
"CarboxylationPathway":1,
"CriticalOxygenContent":[
0.08,
0.08,
0.08,
0.08,
0.08,
0.08
],
"CuttingDelayDays":0,
"DefaultRadiationUseEfficiency":0.5,
"DevelopmentAccelerationByNitrogenStress":1,
"DroughtImpactOnFertilityFactor":0,
"FieldConditionModifier":1,
"InitialKcFactor":0.4,
"InitialOrganBiomass":[
53,
53,
0,
0
],
"InitialRootingDepth":0.1,
"LimitingTemperatureHeatStress":40,
"LuxuryNCoeff":1.3,
"MaxNUptakeParam":3.145,
"MinimumNConcentration":0.005,
"MinimumTemperatureForAssimilation":0,
"OptimumTemperatureForAssimilation":27,
"MaximumTemperatureForAssimilation":35,
"MinimumTemperatureRootGrowth":0,
"NConcentrationAbovegroundBiomass":0.06,
"NConcentrationB0":2,
"NConcentrationPN":1.6,
"NConcentrationRoot":0.02,
"OrganGrowthRespiration":[
0.306,
0.315,
0.338,
0.291
],
"OrganMaintenanceRespiration":[
0.01,
0.03,
0.015,
0.01
],
"PartBiologicalNFixation":0,
"RootFormFactor":3,
"RootGrowthLag":-30,
"RootPenetrationRate":0.0011,
"SamplingDepth":0.9,
"SpecificRootLength":300,
"StageAfterCut":0,
"StageAtMaxHeight":3,
"StageMaxRootNConcentration":[
0.02,
0.02,
0.012,
0.01,
0.01,
0.01
],
"StorageOrgan":[
false,
false,
false,
true
],
"TargetN30":120,
"TargetNSamplingDepth": 230,
"type": "SpeciesParameters"
}
Consistency requirements
Before using a species parameter object, verify the following:
BaseTemperature,CriticalOxygenContent,StageMaxRootNConcentration, andStageMobilFromStorageCoeffcontain one entry for every developmental stage.AbovegroundOrgan,StorageOrgan,InitialOrganBiomass,OrganGrowthRespiration, andOrganMaintenanceRespirationcontain one entry for every crop organ.- Exactly one organ is normally marked as the storage organ.
- Stage references are valid for the number of developmental stages.
DormancyStartDoyandDormancyEndDoyare set only for perennial crops that use dormancy.