The cropland module simulates the dynamics of cropland area and agricultural crop production and calculates corresponding carbon contents and the biodiversity value of the existing cropland.
| Description | Unit | A | |
|---|---|---|---|
| fm_bii_coeff (bii_class44, potnatveg) |
bii coeff | \(unitless\) | x |
| fm_carbon_density (t_all, j, land, c_pools) |
LPJmL carbon density for land and carbon pools | \(tC/ha\) | x |
| fm_luh2_side_layers (j, luh2_side_layers10) |
luh2 side layers | \(grid cell share\) | x |
| vm_bv (j, landcover44, potnatveg) |
biodiversity value for all land cover classes (unweighted) | \(Mha\) | x |
| vm_carbon_stock (j, land, c_pools) |
Carbon stock in vegetation soil and litter for different land types | \(10^6 tC\) | x |
| vm_land (j, land) |
Land area of the different land types | \(10^6 ha\) | x |
| vm_prod (j, k) |
Production in each cell | \(10^6 tDM/yr\) | x |
| vm_yld (j, kve, w) |
Yields (variable because of technical change) | \(tDM/ha/yr\) | x |
| Description | Unit | |
|---|---|---|
| fm_croparea (t_all, j, w, kcr) |
Different croparea type areas | \(10^6 ha\) |
| vm_area (j, kcr, w) |
Agricultural production area | \(10^6 ha\) |
The endo_apr21 realization calculates the crop specific agricultural land use endogenously based on yield data coming from the module 14_yields and the rotational as well as suitability constraints stated in the input data of the module.
Cropland areas are linked to the crop specific production and the carbon content of the different land carbon pools. The crop specific land use areas are also used in 18_residues, 38_factor_costs, 41_area_equipped_for_irrigation, 42_water_demand, 50_nr_soil_budget, 53_methane and 59_som. This realisation also includes the option to set aside a given share of the total available cropland for other land cover classes (by a given target year), in order to provide species habitats and to benefit from ecosystem services in agricultural landscapes.
The total land requirements for cropland are calculated as the sum of crop and water supply type specific land requirements:
\[\begin{multline*} \sum_{kcr,w} vm\_area(j2,kcr,w) = vm\_land(j2,"crop") \end{multline*}\]
We assume that crop production can only take place on suitable cropland area. We use a suitability index (SI) map from Zabel, Putzenlechner, and Mauser (2014) to exclude areas from cropland production that have a low suitability, e.g. due to steep slopes, to estimate the available cropland area. The cultivated area therefore has to be smaller than the available cropland area. Moreover, the available cropland can be reduced by setting aside cropland for other land cover types.
\[\begin{multline*} vm\_land(j2,"crop") \leq \sum_{ct} p30\_avl\_cropland(ct,j2) \end{multline*}\]
As additional constraints minimum and maximum rotational constraints limit the placing of crops. On the one hand, these rotational constraints reflect crop rotations limiting the share a specific crop can cover of the total area of a cluster:
\[\begin{multline*} \sum_{crp\_kcr30(crpmax30,kcr)} vm\_area(j2,kcr,w) \leq \sum_{kcr} vm\_area(j2,kcr,w) \cdot f30\_rotation\_max\_shr(crpmax30) \end{multline*}\]
On the other hand, it reflects boundary conditions such as minimum self sufficiency constraints:
\[\begin{multline*} \sum_{crp\_kcr30(crpmin30,kcr)} vm\_area(j2,kcr,w) \geq \sum_{kcr} vm\_area(j2,kcr,w) \cdot f30\_rotation\_min\_shr(crpmin30) \end{multline*}\]
Agricultural production is calculated by multiplying the area under production with corresponding yields. Production from rainfed and irrigated areas is summed up:
\[\begin{multline*} vm\_prod(j2,kcr) = \sum_{w}\left( vm\_area(j2,kcr,w) \cdot vm\_yld(j2,kcr,w)\right) \end{multline*}\]
Due to the high uncertainty in 2nd generation bioenergy production, irrigated production of bioenergy is deactivated (see presolve statements of crop realization). The carbon content of the above ground carbon pools are calculated as a total for all cropland :
\[\begin{multline*} vm\_carbon\_stock(j2,"crop",ag\_pools) = vm\_land(j2,"crop") \cdot \sum_{ct}fm\_carbon\_density(ct,j2,"crop",ag\_pools) \end{multline*}\]
The biodiversity value for cropland is calculated separately for annual and perennial crops:
\[\begin{multline*} vm\_bv(j2,"crop\_ann",potnatveg) = \sum_{crop\_ann30,w} vm\_area(j2,crop\_ann30,w) \cdot fm\_bii\_coeff("crop\_ann",potnatveg) \cdot fm\_luh2\_side\_layers(j2,potnatveg) \end{multline*}\]
\[\begin{multline*} vm\_bv(j2,"crop\_per",potnatveg) = \sum_{crop\_per30,w} vm\_area(j2,crop\_per30,w) \cdot fm\_bii\_coeff("crop\_per",potnatveg) \cdot fm\_luh2\_side\_layers(j2,potnatveg) \end{multline*}\]
First, all 2nd generation bioenergy area is fixed to zero, irrespective of type and rainfed/irrigation.
vm_area.fx(j,kbe30,w)=0;Second, the bounds for 2nd generation bioenergy area are released depending on the dynamic sets bioen_type_30 and bioen_water_30.
vm_area.up(j,bioen_type_30,bioen_water_30)=Inf;Set aside cropland policy is fading in after 2020
p30_avl_cropland(t,j) = f30_avl_cropland(j,"%c30_marginal_land%") *
(1 - f30_set_aside_fader(t,"%c30_set_aside_target%") *
(s30_set_aside_shr * sum(cell(i,j), p30_region_setaside_shr(i))
+ s30_set_aside_shr_noselect * sum(cell(i,j), 1-p30_region_setaside_shr(i)))); Limitations There are currently no known limitations of this realization.
| Description | Unit | A | |
|---|---|---|---|
| f30_avl_cropland (j, marginal_land30) |
Available land area for cropland | \(10^6 ha\) | x |
| f30_avl_cropland_iso (iso, marginal_land30) |
Available land area for cropland at ISO level | \(10^6 ha\) | x |
| f30_rotation_max_shr (crp30) |
Maximum allowed area shares for each crop type | \(1\) | x |
| f30_rotation_min_shr (crp30) |
Minimum allowed area shares for each crop type | \(1\) | x |
| f30_set_aside_fader (t_all, set_aside_target30) |
Fader for share of set aside cropland | \(unitless\) | x |
| i30_avl_cropland_iso (iso) |
Available land area for cropland at ISO level | \(10^6 ha\) | x |
| p30_avl_cropland (t, j) |
Total available land for crop cultivation | \(10^6 ha\) | x |
| p30_country_dummy (iso) |
Dummy parameter indicating whether country is affected by selected set-aside policy | \(1\) | x |
| p30_region_setaside_shr (i) |
Set-aside share of the region | \(1\) | x |
| q30_avl_cropland (j) |
Available cropland constraint | \(10^6 ha\) | x |
| q30_bv_ann (j, potnatveg) |
Biodiversity value of annual cropland | \(Mha\) | x |
| q30_bv_per (j, potnatveg) |
Biodiversity value of perennial cropland | \(Mha\) | x |
| q30_carbon (j, ag_pools) |
Cropland above ground carbon content calculation | \(10^6 tC\) | x |
| q30_cropland (j) |
Total cropland calculation | \(10^6 ha\) | x |
| q30_prod (j, kcr) |
Production of cropped products | \(10^6 tDM\) | x |
| q30_rotation_max (j, crp30, w) |
Local maximum rotational constraints | \(10^6 ha\) | x |
| q30_rotation_min (j, crp30, w) |
Local minimum rotational constraints | \(10^6 ha\) | x |
| s30_set_aside_shr | Share of available cropland that is witheld for other land cover types | \(1\) | x |
| s30_set_aside_shr_noselect | Share of available cropland that is witheld for other land cover types | \(1\) | x |
| description | |
|---|---|
| ag_pools(c_pools) | Above ground carbon pools |
| bii_class44 | bii coefficent land cover classes |
| bioen_type_30(kbe30) | dynamic set bioen type |
| bioen_water_30(w) | dynamic set bioen water |
| c_pools | Carbon pools |
| cell(i, j) | number of LPJ cells per region i |
| crop_ann30(kcr) | annual crops |
| crop_per30(kcr) | perennial crops |
| crp_kcr30(crp30, kcr) | Mapping of crop types into crop rotation types |
| crp30 | Crop rotation types |
| crpmax30(crp30) | Maximum crop rotation |
| crpmin30(crp30) | Minimum crop rotation |
| ct(t) | Current time period |
| i | all economic regions |
| i_to_iso(i, iso) | mapping regions to iso countries |
| iso | list of iso countries |
| j | number of LPJ cells |
| j2(j) | Spatial Clusters (dynamic set) |
| k(kall) | Primary products |
| kbe30(kcr) | bio energy activities |
| kcr(kve) | Cropping activities |
| kve(k) | Land-use activities |
| land | Land pools |
| landcover44 | land cover classes used in bii calculation |
| luh2_side_layers10 | side layers from LUH2 |
| marginal_land30 | Marginal land scenarios |
| policy_countries30(iso) | countries to be affected by set-aside policy |
| potnatveg(luh2_side_layers10) | potentially forested biomes |
| t_all(t_ext) | 5-year time periods |
| t_past(t_all) | Timesteps with observed data |
| t(t_all) | Simulated time periods |
| Target | year for set aside policy |
| type | GAMS variable attribute used for the output |
| w | Water supply type |
Jan Philipp Dietrich, Florian Humpenöder, Benjamin Bodirsky
10_land, 14_yields, 17_production, 18_residues, 38_factor_costs, 41_area_equipped_for_irrigation, 42_water_demand, 44_biodiversity, 50_nr_soil_budget, 52_carbon, 53_methane, 59_som
Zabel, Florian, Birgitta Putzenlechner, and Wolfram Mauser. 2014. “Global Agricultural Land Resources A High Resolution Suitability Evaluation and Its Perspectives Until 2100 Under Climate Change Conditions.” PLOS ONE 9 (9): e107522. https://doi.org/10.1371/journal.pone.0107522.