RUFAS.routines.field.soil.phosphorus_cycling.phosphorus_mineralization module

class RUFAS.routines.field.soil.phosphorus_cycling.phosphorus_mineralization.PhosphorusMineralization(soil_data: SoilData | None = None, field_size: float | None = None)

Bases: object

Manages the transfer of phosphorus between the various inorganic phosphorus pools in each soil layer, based on the “Inorganic Soil P Model” section of SurPhos.

Parameters

soil_dataSoilData, optional

An instance of SoilData to be used for tracking manure phosphorus activity. If not provided, a new instance will be created with the given field size.

field_sizefloat, optional

The size of the field (ha).

Attributes

dataSoilData

The SoilData object that contains data and functionality related to soil and phosphorus properties.

__init__(soil_data: SoilData | None = None, field_size: float | None = None)

mineralize_phosphorus(field_size) → None

This method handles the daily re-averaging of the phosphorus sorption parameter, then iterates through the soil profile and calls the appropriate method for adjusting its phosphorus pools.

Parameters

field_sizefloat

Size of the field (ha).

Notes

The constants used in many of this module’s subroutines differed between older versions of this code and the literature. The constants from the old code are used here.

Sorption is the process of phosphorus mineralizing from the labile inorganic pool to the active inorganic pool, and desorption is the other way around.

When sorption occurs, the program checks whether the current phosphorus imbalance is greater than it was the day before, and if so it resets unbalanced counter for the labile pool, which has the effect of sorping the maximum amount possible from the labile pool.

static _recompute_mean_phosphorus_sorption_parameter(mean_sorption_parameter: float, current_sorption_parameter: float) → float

Recalculates the mean sorption parameter based on current day’s condition.

Parameters

mean_sorption_parameterfloat

The mean phosphorus sorption parameter of the given soil layer (unitless).

current_sorption_parameterfloat

The phosphorus sorption parameter of the given soil layer calculated with the layer’s current conditions

(unitless).

Returns

float

The mean phosphorus sorption parameter that has been adjusted for the current day’s amount of labile inorganic phosphorus present (unitless).

References

SurPhos Fortran code, pminrl.f, lines 48 - 51

Notes

The phosphorus sorption parameter, in the words of Pete Vadas, “represents sort of a long term chemical characteristic of the soil and should NOT be calculated every day. There can be big changes in labile P when P is added to soils in fertilizer and manure, and we don’t want PSP changing rapidly.” Be recalculating the phosphorus sorption parameter with this equation every day (as opposed to recalculating it with calculate_phosphorus_sorption_parameter() in LayerData), we keep changes in it limited. This equation approximates taking a weighted average over a time span that is determined by the days_to_average_over_value, currently set to the length of a year.

static _determine_phosphorus_imbalance(labile_phosphorus: float, active_phosphorus: float, sorption_parameter: float) → float

Calculates the imbalance of phosphorus between the labile and active inorganic pools.

Parameters

labile_phosphorusfloat

Labile inorganic phosphorus content of this soil layer (kg / ha).

active_phosphorusfloat

Active inorganic phosphorus content of this soil layer (kg / ha).

sorption_parameterfloat

The phosphorus sorption parameter of this layer (unitless).

Returns

float

A value indicating how unbalanced the labile and active inorganic phosphorus pools are (unitless).

References

SWAT eqn. 3:2.3.2, 3 (Only the conditions that proceed the ‘if’)

Notes

A negative value returned indicates that there is more active phosphorus than there should be, a positive value indicates that there is more labile phosphorus than there should be, and a return value of zero indicates that the two pools are balanced.

static _calculate_phosphorus_desorption(active_inorganic_unbalanced_counter: int, sorption_parameter: float, phosphorus_balance: float) → float

Calculates how much phosphorus should be desorped in the given soil layer.

Parameters

active_inorganic_unbalanced_counterint

The number of days that the active inorganic phosphorus pool has been greater than it would be when in equilibrium with the labile inorganic phosphorus pool.

sorption_parameterfloat

The mean phosphorus sorption parameter that has been adjusted for the current day’s amount of labile inorganic phosphorus present (unitless).

phosphorus_balancefloat

A value indicating how unbalanced the labile and active inorganic phosphorus pools are (unitless).

Returns

float

The amount of phosphorus that should be removed from the active inorganic phosphorus pool to put it in equilibrium with the labile inorganic phosphorus pool (kg / ha).

References

SurPhos pminrl.f, lines 69, 70 Vadas P.A., Krogstad T., Sharpley A.N. (2006) Modeling phosphorus transfer between labile and nonlabile soil

pools: Updating the EPIC model. Soil Science Society of America Journal 70:736-743. DOI: Doi 10.2136/Sssaj2005.0067. (Eqn. [8])

static _determine_desorption_base(sorption_parameter: float) → float

This method calculates a value used to determine how much phosphorus is desorped from the active inorganic phosphorus pool in the labile organic phosphorus pool.

Parameters

sorption_parameterfloat

The mean phosphorus sorption parameter that has been adjusted for the current day’s amount of labile inorganic phosphorus present (unitless).

Returns

float

A value (named ‘base’ in code and literature) that is used to determine how much phosphorus is transferred from the active inorganic phosphorus pool to the labile inorganic phosphorus pool (unitless).

References

SurPhos pminrl.f, line 59 Vadas P.A., Krogstad T., Sharpley A.N. (2006) Modeling phosphorus transfer between labile and nonlabile soil

pools: Updating the EPIC model. Soil Science Society of America Journal 70:736-743. DOI: Doi 10.2136/Sssaj2005.0067. (Eqn. [7])

static _calculate_phosphorus_sorption(labile_inorganic_unbalanced_counter: int, sorption_parameter: float, phosphorus_balance: float) → float

Calculates how much phosphorus should be sorped in the given soil layer.

Parameters

labile_inorganic_unbalanced_counterint

The number of days that the labile inorganic phosphorus pool has been greater than it would be when in equilibrium with the labile inorganic phosphorus pool.

sorption_parameterfloat

The mean phosphorus sorption parameter that has been adjusted for the current day’s amount of labile inorganic phosphorus present (unitless).

phosphorus_balancefloat

A value indicating how unbalanced the labile and active inorganic phosphorus pools are (unitless).

Returns

float

The amount of phosphorus that should be removed from the labile inorganic phosphorus pool to put it in equilibrium with the active inorganic phosphorus pool (kg / ha).

References

SurPhos pminrl.f, lines 92, 94 Vadas P.A., Krogstad T., Sharpley A.N. (2006) Modeling phosphorus transfer between labile and nonlabile soil

pools: Updating the EPIC model. Soil Science Society of America Journal 70:736-743. DOI: Doi 10.2136/Sssaj2005.0067. (Eqn. [4])

static _determine_sorption_scalar(sorption_parameter: float) → float

Determines the scalar used to calculate the sorption factor.

Parameters

sorption_parameterfloat

The mean phosphorus sorption parameter that has been adjusted for the current day’s amount of labile inorganic phosphorus present (unitless).

Returns

float

The scalar used in determining how much phosphorus is removed from the labile inorganic phosphorus pool and transferred to the active inorganic phosphorus pool (unitless).

References

SurPhos pminrl.f, line 56 Vadas P.A., Krogstad T., Sharpley A.N. (2006) Modeling phosphorus transfer between labile and nonlabile soil

pools: Updating the EPIC model. Soil Science Society of America Journal 70:736-743. DOI: Doi 10.2136/Sssaj2005.0067. (Eqn. [6])

static _determine_sorption_exponent(sorption_scalar: float) → float

Determines the exponential term used to calculate the sorption factor.

Parameters

sorption_scalar

The scalar used in determining how much phosphorus is removed from the labile inorganic phosphorus pool and transferred to the active inorganic phosphorus pool (unitless).

Returns

float

A value used as an exponential term when determining the phosphorus sorption rate (unitless).

References

SurPhos pminrl.f, line 57 Vadas P.A., Krogstad T., Sharpley A.N. (2006) Modeling phosphorus transfer between labile and nonlabile soil

pools: Updating the EPIC model. Soil Science Society of America Journal 70:736-743. DOI: Doi 10.2136/Sssaj2005.0067. (Eqn. [5])

static _determine_stable_to_active_phosphorus_mineralization(stable_phosphorus: float, active_phosphorus: float) → float

Determines how much phosphorus should be transferred from the stable pool to the active pool.

Parameters

stable_phosphorusfloat

Stable inorganic phosphorus content of this soil layer (kg / ha).

active_phosphorusfloat

Active inorganic phosphorus content of this soil layer (kg / ha).

Returns

float

The amount of phosphorus to be transferred from the stable inorganic phosphorus pool to the active phosphorus inorganic pool (kg / ha).

References

SurPhos pminrl.f, lines 108 - 110