Calculate application rates for active ingredients — application_rate_g_per

An application rate in g active substance/ha is calculated from information on dosage (product concentration in the application solution), application volume, or directly from the product application rate. This is complicated by the fact that a rate ("expenditure" in the XML file) with units l/ha can refer to the application solution or to the liquid product.

Usage

application_rate_g_per_ha(
  product_uses,
  aggregation = c("max", "mean", "min"),
  dosage_units = c("percent_ww", "percent_vv", "state_of_matter"),
  skip_l_per_ha_without_g_per_L = TRUE,
  fix_l_per_ha = TRUE
)

Arguments

product_uses: A tibble containing the columns 'pNbr', 'use_nr', 'application_area_de', 'min_dosage', 'max_dosage', 'min_rate', 'max_rate', from the 'uses' table in a srppp_dm object, as well as the columns 'percent' and 'g_per_L' from the 'ingredients' table in a srppp_dm object.
aggregation: How to represent a range if present, e.g. "max" (default) or "mean".
dosage_units: If no units are given, or units are "%", then the applied amount in g/ha is calculated using a reference application volume and the dosage. As the dosage units are not explicitly given, we can specify our assumptions about these using this argument (currently not implemented, i.e. specifying the argument has no effect).
skip_l_per_ha_without_g_per_L: Per default, uses where the use rate has units of l/ha are skipped, if there is not product concentration in g/L. This was also done in the 2023 indicator project.
fix_l_per_ha: During the review of the 2023 indicator project calculations, a number of cases were identified where the unit l/ha specifies a water volume, and not a product volume. If TRUE (default), these cases are corrected, if FALSE, these cases are discarded.

Value

A tibble containing one additional column 'rate_g_per_ha'

Details

In some cases (currently one), external information was found, indicating that the "expenditure" is an application volume l_per_ha_is_water_volume.

Note

A reference application volume is used if there is no 'expenditure'. It is selected only based on the product application area. This is not correct if hops ('Hopfen') is the culture, as it has a unique reference application volume of 3000 L/ha.

Applications to hops were excluded for calculating mean use rates in the indicator project (Korkaric 2023), arguing that it is not grown in large areas in Switzerland.

Examples

if (FALSE) { # \dontrun{
library(srppp)
library(dplyr, warn.conflicts = FALSE)
library(dm, warn.conflicts = FALSE)
sr <- srppp_dm()

product_uses_with_ingredients <- sr$substances |>
  filter(substance_de %in% c("Halauxifen-methyl", "Kupfer (als Kalkpr\u00E4parat)")) |>
  left_join(sr$ingredients, by = "pk") |>
  left_join(sr$uses, by = "pNbr") |>
  left_join(sr$products, by = "pNbr") |>
  select(pNbr, name, use_nr,
    min_dosage, max_dosage, min_rate, max_rate, units_de,
    application_area_de,
    substance_de, percent, g_per_L)

application_rate_g_per_ha(product_uses_with_ingredients) |>
  filter(name %in% c("Cerelex", "Pixxaro EC", "Bordeaux S")) |>
  select(ai = substance_de, app_area = application_area_de,
    min_d = min_dosage,  max_d = max_dosage,
    min_r = min_rate, max_r = max_rate,
    units_de, rate = rate_g_per_ha) |>
  print(n = Inf)
} # }