OBI-16 #184
OBI-16 #184
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| @@ -71,11 +71,11 @@ calc_slv <- function(B_LU_BRP, B_SOILTYPE_AGR, B_AER_CBS,A_SOM_LOI,A_S_RT, D_BDS | |||
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| # Calculate SLV for grass (deze formule: Stot = g/kg en dichtheid in g/cm3) | |||
| dt.grass <- dt[crop_category == "grasland"] | |||
| dt.grass[, value := 17.8 * A_S_RT * 0.001 * D_BDS * 0.001] | |||
| dt.grass[, value := 17.8 * A_S_RT * D_BDS * 0.001] | |||
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This is incorrect, see page 18 in Bemestingsadvies grasland. Soils are low in S supply when S supplying capacity is lower than 17 and its high when SLV exceeds the 23 (for grassland). If S total is 650 mg/kg (a realistic value), then SLV is around 15 kg / ha. If you remove this correction, then this change would result in a S supply of 15.000 kg S/ha, that seems unrealistic to me. Or is the unit of D_BDS different here?
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| # Calculate SLV for maize for 0-25 cm depth | ||
| dt.maize <- dt[crop_category == "mais"] | ||
| dt.maize[, value := 41.2 * A_S_RT * 0.001 * D_BDS * 2.5 * 0.001] | ||
| dt.maize[, value := 41.2 * A_S_RT * D_BDS * 2.5 * 0.001] | ||
| # correction for the length of growing season (43.5%) |
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here the same. if S is too low, there shoulde be another reason than this unit correction
| @@ -90,7 +90,7 @@ calc_slv <- function(B_LU_BRP, B_SOILTYPE_AGR, B_AER_CBS,A_SOM_LOI,A_S_RT, D_BDS | |||
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| # calculate C-stock (kg/ ha) and CS ratio (sven: check unit) | |||
| dt.arable[,D_OC := A_SOM_LOI * 100 * 100 * 0.3 * D_BDS * 0.01] | |||
| dt.arable[,A_CS_RAT := A_SOM_LOI * 10 / (A_S_RT * 0.001)] | |||
| dt.arable[,A_CS_RAT := A_SOM_LOI * 10 / (A_S_RT)] | |||
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no this is incorrect. CS_RAT is the SOM-to-S ratio. Note that this is rather SOM stock than SOC, but anyhow, A_SOM_LOI times 10 results in units g/kg, so when dividing by A_S_RT * 0.001 the resulting unit is dimensionless.
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note that sulpher is depreciated and sulfer is the new one. So, you updated the old file.
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i don't think that the low SLV is an issue due to the units here.
the equations in original are according to the current guidelines in fertilizer recommendation.
removing the 0.001 as done in this repo results in SLV values exceeding 1000 kg SLV / ha, very unrealistic. The values should vary around 5 to 50 kg S / ha for grassland and maize at least, and they do.
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Ok, thanks for checking. Is then maybe because the evaluation function is incorrect: Open-Bodem-Index-Calculator/R/sulfur.R Line 296 in 79c67aa Grass and maize use the same parameters, so can we not use those parameters for arable as well? Open-Bodem-Index-Calculator/R/sulfur.R Line 301 in 79c67aa Open-Bodem-Index-Calculator/R/sulfur.R Line 305 in 79c67aa |
Fixed
slvby removing the not applicable conversion from g S /kg to mg S /kg for A_S_RT [OBI-16]