STIR : Calculate STIR value

The function calculates the soil tillage intensity rating (STIR) value of tillage and sowing operations. By default, the STIR() function of SoilManageR operates on SI units (cm and km/h) and not in imperial units (inch, mph) as the original STIR equation \insertCiteRUSLE2SoilManageR. However, the user can specifiy that the input is in imperial units. The function can process custom input, if no such input is provided it assumes default values from the STIR_value_LUT .

Usage STIR( device = NA, speed = NA, speed_unit = "km/h", type_modifier = NA, depth = NA, depth_unit = "cm", area_disturbed = NA, original.STIR.value = FALSE ) Arguments

tillage or sowing implement or operation, must match predefined list, or all necessary inputs (speed, type modidifier, depth, area_disturbed) must be provided

speed of the operation (km/h or mph)

unit of the speed input, must be either NA, "km/h" or "mph". Default value is "km/h"

tillage operation type modifier, must be a value between 0 and 1

depth of the soil that is affected by the operation (cm or inch)

unit of the depth input, must be either NA, "cm" or "inch". Default value is "cm"

share of the surfave that is disturbed by the operation (0 to 1)

logical value, if TRUE, the original STIR value of the operation in the STIR_value_LUT (instead of the calculated STIR value) is returned. Default value is FALSE

Details

The concept of the STIR value was developed within the RUSLE2 framework by the \insertCiteRUSLE2;textualSoilManageR. The STIR equation is defined as

STIR = (0.5 * speed) * (3.25 * type_) * depth * area_

where speed and depth are provided in mph and inches(!). For the purpose of this function we assume that ⁠1 inch = 2.54 cm⁠ and ⁠1 mph = 1.609 km/h⁠ . The tillage type_ is defined to be:

1.00 for inversion operation
0.80 for mixing and some inversion operations
0.70 for mixing operations
0.40 for lifting and fracturing operations
0.15 for compression operations

In the STIR_value_LUT there are more than 400 operations, incl. the original operations from the RUSLE2 software (as of 2023-02-24) and operations defined by the SoilX project.

For further details on the STIR please consider the RUSLE2 website (https://fargo.nserl.purdue.edu/rusle2_dataweb/RUSLE2_Index.htm) or the description of the SoilManageR package

Value

STIR value of the operation

References \insertAllCited See Also

tillage_intensity() to calculate STIR values for management_df
STIR_values_LUT() for the reference data used by the STIR() function

Examples #example without additional information STIR("plough") #example with additional information STIR("rotary_harrow", depth = 15) #custom example STIR(speed = 10, type_modifier = 0.8, depth = 15, area_disturbed = 0.45) #example that returns orginial STIR value STIR("plough", original.STIR.value = TRUE) #example that uses imperial units STIR("plough", depth = 5, depth_unit = "inch", speed = 8, speed_unit = "mph")

Related to STIR in SoilManageR.

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