calc_psp: Calculate the precipitation surplus

In OBIC: Calculate the Open Bodem Index (OBI) Score

Calculate the precipitation surplus

Description

This function calculates the precipitation surplus (in mm / ha) given the crop rotation plan. For the months with green manure (M_GREEN_START to and including M_GREEN_TERMINATE), the makkink correction factor is increased to 0.6. If the value is already higher than 0.6, no change is made to the makkink factor. For most cultivations, including green manure decreases the precipitation suprlus by increasing the evapotranspiration.

Usage

calc_psp(B_LU_BRP, M_GREEN, M_GREEN_START = 10L, M_GREEN_TERMINATE = 3L)

Arguments

B_LU_BRP	(numeric) The crop code from the BRP
M_GREEN	(boolean) A soil measure. Are catch crops sown after main crop (optional, options: TRUE, FALSE)
M_GREEN_START	(integer) Month in which the green manure is sown
M_GREEN_TERMINATE	(integer) Month in which the green manure is terminated, this month is included as month with green manure

Details

This function is calculates a precipitation surplus over 12 months taking green manures into account. The function does not take crop rotations or successive years into account. As such, including a winter cereal, which modifies evapotranspiration from January to August, does not alter the autumn evapotranspiration. If for example, a crop rotation includes potato followed by winter wheat, the year with potato cultivation should have M_GREEN = TRUE. The winter wheat acts as a green manure/catch crop for the potato's year.

Value

The estimated precipitation surplus (in mm / ha) depending on averaged precipitation and evaporation. A numeric value.

Examples

calc_psp(B_LU_BRP = 265, M_GREEN = TRUE)
calc_psp(B_LU_BRP = c(265,1019,265,1019), M_GREEN = rep(TRUE,4))
calc_psp(B_LU_BRP = c(2014, 2767), M_GREEN = rep(TRUE,2),
             M_GREEN_START = c(10L, 11L), M_GREEN_TERMINATE = c(12L, 3L))

OBIC documentation built on Feb. 11, 2026, 5:06 p.m.