SoilManageR (version 1.0.1)

C_input_crops: Estimate C inputs by crops

Description

Calculates the estimated carbon (C) input into the soil system by harvested main crops.

Usage

C_input_crops(
  crop,
  crop_product = NA,
  crop_residue = NA,
  harvest_index = NA,
  variable_harvest_index = NA,
  HI_intercept = NA,
  HI_slope = NA,
  shoot_root_ratio = NA,
  root_exudation_factor = NA,
  Cc_product = 450,
  Cc_residue = 450,
  Cc_root = 450,
  straw.removal = NA,
  fixed_belowground_input = NA,
  fixed_C_input_root = NA,
  return.comment = FALSE
)

Value

a tibble with the following parameters:

• C_input_product: Estimated soil carbon input from product (e.g. damaged patatos) (kgC/ha),

• C_input_straw: Estimated soil carbon input by straw or other residues (kgC/ha),

• C_input_root: Estimated soil carbon input by roots (kgC/ha),

• C_input_exudate: Estimated soil carbon input by roots (kgC/ha),

• C_input_total: Total estimated Soil carbon input, sum of C_input_straw, C_input_root, C_input_exudate (kgC/ha),

• comment (optional): comment on the derived values

Arguments

crop

Crop type. Must match predefined list (see C_input_crops_LUT)

crop_product

(optional) Dry weight of the exported product, i.e. yield. Default value is taken from table (tDM/ha)

crop_residue

(optional) Dry weight of the residues of the main crop (e.g., straw, sugar beet leaves) (tDM/ha)

harvest_index

(optional) Ratio of the product to the total above ground biomass

variable_harvest_index

(optional) Logical value that is TRUE if the variable harvest index assumptions of Fan et al. (2017) are to be applied (TRUE / FALSE)

HI_intercept

(optional) Intercept of the variable harvest index. Values provided by Fan et al. (2017)

HI_slope

(optional) Slope of the variable harvest index. Values provided by Fan et al. (2017) (ha/tDM)

shoot_root_ratio

(optional) Ratio of the total above ground biomass to the root biomass

root_exudation_factor

(optional) Ratio of the root exudated C to the C in the root biomass

Cc_product

(optional) C concentration in the exported product. Default value is 450 (gC/kgDM)

Cc_residue

(optional) C concentration in the residues of the main crop. Default value is 450 (gC/kgDM)

Cc_root

(optional) C concentration in the roots. Default value is 450 (gC/kgDM)

straw.removal

(optional) Logical value that is TRUE if straw is removed at harvest.

• When NA then SR value from table is take

• When TRUE SS is 1

• When FALSE SS is 0.

• Default value is NA

fixed_belowground_input

(optional) Logical value that is TRUE if fixed below ground Carbon inputs are to be assumed (e.g. for temporary leys) (TRUE / FALSE)

fixed_C_input_root

(optional) amount of root C that is assumed if fixed_belowground_input is TRUE (kgC/ha)

return.comment

(optional) logical value if comment are returned or not. Default = FALSE (TRUE/FALSE)

Details

The annual C input by crops were estimated based on crop type and crop yield with the allometric functions of bolinder2007;textualSoilManageR:

$$ C_{Product} = Product * CC_{Product} $$ $$ C_{Straw} = {Product}* \frac{1 - HI}{HI} * CC_{Straw} $$ $$ C_{Root} = \frac{Product}{SRR*HI} * CC_{Root} $$ $$ C_{Exudates} = C_{Root} * REF $$

Where \(C\) is the C per fraction (in kgC/ha) and \(CC\) is the C content of given fraction (kgC/tDM). \(Prodcuct\) is the dry matter yield of a crop in tDM/ha, \(HI\) is the harvest index (ratio of product total of product and straw), \(SRR\) is the ratio of the shoot biomass (product and straw) to the root biomass, and \(REF\) is the root exudation factor (i.e., the ratio of the C exudated by the roots to the C in the root biomass). All fractions are multiplied with a crop and fraction specific \(S\)-factor that determines the share of the fraction that is returned to the soil.

If not mentioned otherwise parameters were taken from the publications of bolinder2007;textualSoilManageR, keel2017;textualSoilManageR or wuest2020;textualSoilManageR. Parameters for potatoes and sugar beets were derived from bolinder2015;textualSoilManageR For temporary leys we assumed yield-independent annual \(C_{Root}\) of 1.5 MgC/ha and a \(REF\) of 0.5 taghizadeh-toosi2020SoilManageR. Furthermore, like wuest2020;textualSoilManageR, the belowground C input (\(C_{Root} + C_{Exudates}\)) of corn maize, silage maize and cereals were fixed to 0.46 MgC/ha, 1.1 MgC/ha and 0.6 MgC/ha respectively, based on the values from hirte2018;textualSoilManageR. Additionally, we applied the yield dependent harvest index \((HI = Intercept + Product * Slope)\) proposed by fan2017;textualSoilManageR for cereals, faba beans, peas, corn, rapeseed, and soybeans.

Reference yields were derived from the Swiss fertilizer recommendations GRUD2017_ch8;textualSoilManageR.

All default values can be found in the look-up-table C_input_crops_LUT.

References

See Also

• C_input() to calculate C inputs for a management_df

• C_input_cover_crops() to calculate C input for cover crops

• CN_input_amendments() to calculate C (and N) inputs for organic amendments

• C_input_crops_LUT() for the look-up-table for crop reference values

Examples

#example without yield information, default yield is assumed
C_input_crops("wheat, winter")

#example with yield information and straw retention
C_input_crops("barley, spring", crop_product = 4.5, straw.removal = FALSE)

#example with more information
C_input_crops("barley, spring", crop_product = 4.5, harvest_index = 0.4,
              shoot_root_ratio = 2.4, root_exudation_factor = 0.5)

#example with variable harvest index
C_input_crops("barley, spring", crop_product = 4.5, variable_harvest_index = TRUE,
              HI_intercept = 0.35, HI_slope = 0.015, shoot_root_ratio = 2.4,
              root_exudation_factor = 0.5)

#example with fixed below ground input
C_input_crops("maize, silage", crop_product = 18.5, 
              fixed_belowground_input = TRUE, fixed_C_input_root = 1500,
              root_exudation_factor = 0.3)