SoilManageR (version 1.0.1)

STIR: Calculate STIR value

Description

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 RUSLE2SoilManageR. 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
)

Value

STIR value of the operation

Arguments

device

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

speed

speed of the operation (km/h or mph)

speed_unit

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

type_modifier

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

depth

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

depth_unit

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

area_disturbed

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

original.STIR.value

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 RUSLE2;textualSoilManageR. The STIR equation is defined as

$$STIR = (0.5 * speed) * (3.25 * type_{modifier}) * depth * area_{disturbed}$$

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 \(type_{modifier}\) 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

References

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")