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Crop Land Module (30_crop)

Description

The crop land module simulates the dynamics of cropland area and agricultural crop production and calculates corresponding carbon contents of the existing cropland. Based on yield data coming from 14_yields the module calculates agricultural land-use, cropland carbon contents and agricultural production. Rotational constaints thereby assure a minimum level of crop diversity. The module is also strongly connected to 38_factor_costs which determines an important part of the related production costs.

Interfaces

Input

Name Description Unit A
vm_prod(j,kcr) production in each cell mio. ton DM x
vm_land(j,"crop",siclass) The siclass-specific cropland area in each cell mio. ha x
vm_yld(j,kcr,w) agricultural yields ton DM per ha x
vm_carbon_stock(j,"crop",c_pools) The cell and carbon pool specific carbon stock of cropland mio. tC x
fm_carbon_density(t,j,"crop",c_pools) carbon density in vegetation soil and litter of current time step tC/ha x

The last columns of the table indicate the usage in the different realizations (numbered with capital letters)

Output

Name Description Unit
vm_area(j,kcr,w) agricultural production area mio. ha

Interface plot


Figure 0: Information exchange among modules

Current realizations and their limitations

(A) endo_jun13 (default)

The endo_jun13 realization consists of a total of five equations for calculations of land use, production and carbon contents.

In the first equation the total land requirements for cropland are calculated as the sum of crop-specific land requirements. We assume that crop production can only take place on suitable cropland area; we use the suitability index (SI) to exclude areas from cropland production that have low suitability ("nsi0"), e.g. due to strong slopes [Krause et al1 (2013)]. The cultivated area therefore has to equal the "si0" cropland area, while non-suitable cropland with "nsi0" is fixed to 0:

\begin{equation}
vm\_land(j,\text{"crop"},\text{"si0"}) = \sum_{kcr,w} vm\_area(j,kcr,w)\\
vm\_land.fx(j,\text{"crop"},\text{"nsi0"}) = 0\\
\end{equation}

Agricultural production is also calculated straightforward by multiplying area under production with corresponding yields. Production from rainfed and irrigated areas is summed up to one cellular production:

\begin{equation}
vm\_prod(j,kcr) = \sum_w vm\_area(j,kcr,w) \cdot vm\_yld(j,kcr,w)
\end{equation}

As additional constraints minimum and maximum rotational constraints are active which are limiting the allowed distribution of crops. These rotational constraints are used to reflect on one hand crop rotations which limit the share of a specific crop which can be produced on average over time, on the other hand it reflects boundary conditions such as minimum self sufficiency constraints:

\begin{equation}
\sum_{kcr(crp30)} vm\_area(j,kcr,w) \leq \sum_{kcr} vm\_area(j,kcr,w) \cdot f30\_rotation\_max\_shr(crp30) \\
\sum_{kcr(crp30)} vm\_area(j,kcr,w) \geq \sum_{kcr} vm\_area(j,kcr,w) \cdot f30\_rotation\_min\_shr(crp30)
\end{equation}

Due to the high uncertainty in 2nd generation bioenergy production, irrigated production of bioenergy is deactivated:

\begin{equation}
vm\_area.fx(j,(\text{"begr"}),\text{"irrigated"}) = 0 \\
vm\_area.fx(j,(\text{"betr"}),\text{"irrigated"}) = 0
\end{equation}

Carbon stocks of cropland are calculated as product of carbon density as it comes from the 14_yields module and total cropland:

\begin{equation}
vm\_carbon\_stock(j,\text{"crop"},c\_pools) = \sum_{si,ct} vm\_land(j,\text{"crop"},si) \cdot *fm\_carbon\_density(ct,j,"crop",c\_pools)
\end{equation}

Limitations
There are currently no known limitations of this realization

Definitions

Name Description Unit A
$vm_area(j,kcr,w)$ agricultural production area mio. ha x
$f30\_rotation\_max\_shr(crp30)$ Max allowed shares for each crop demand type - x
$f30\_rotation\_min\_shr(crp30)$ Min allowed shares for each crop demand type - x
$crp\_kcr30$ crop rotation types x

References

1 Krause M., Lotze-Campen H., Popp A., Dietrich J.P., and Bonsch M. 2013. “Conservation of Undisturbed Natural Forests and Economic Impacts on Agriculture.” Land Use Policy 30 (1): 344–54. doi:10.1016/j.landusepol.2012.03.020.

Developer(s)

Jan Philipp Dietrich, Florian Humpenöder, Benjamin Bodirsky

See Also

Overview, 14_yields, 38_factor_costs, 39_landconversion, 21_trade