WOLFRAM SYSTEMMODELER

Food_Production

Food production

Diagram

Wolfram Language

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SystemModel["SystemDynamics.WorldDynamics.World3.Food_Production"]
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Information

This model describes the production of food. Food is a controlled variable, as farmers decide what to grow and how much to grow on the basis of their perception of what they can sell. Consequently, the model uses the perceived food ratio as a state variable. If the farmers decide that too much food is being produced already, they'll produce less next year, and vice versa.

A second state variable describes the capital that is being invested in growing food. Since that capital (for example, the capital expended in buying food harvesting machines) cannot be allocated or freed instantaneously, it makes sense to maintain also that variable as a state variable.

The agricultural input is measured in dollars/year, whereas the food ratio is dimensionless.

Public Parameters (11)

agr_inp_init

Value: 5000000000.0

Type: Real (dollar/yr)

Description: Initial agricultural input

food_short_perc_del

Value: 2

Type: Real (yr)

Description: Food shortage perception delay

land_fr_harvested

Value: 0.7

Type: Real

Description: Land fraction harvested

p_avg_life_agr_inp_1

Value: 2

Type: Real (yr)

Description: Default average life of agricultural input

p_avg_life_agr_inp_2

Value: 2

Type: Real (yr)

Description: Controlled average life of agricultural input

p_land_yield_fact_1

Value: 1

Type: Real

Description: Default land yield factor

perc_food_ratio_init

Value: 1

Type: Real

Description: Initial perceived food ratio

processing_loss

Value: 0.1

Type: Real

Description: Processing loss

subsist_food_pc

Value: 230

Type: Real (kg/yr)

Description: Available per capita food

t_policy_year

Value: 4000

Type: Real (yr)

Description: Year of policy change

tech_dev_del_TDD

Value: 20

Type: Real (yr)

Description: Technology development time

Connectors (17)

ind_out_pc

Type: MassInPort

Description: Per capita annual industrial output

industrial_output

Type: MassInPort

Description: Annual industrial output

fr_inp_al_land_dev

Type: MassInPort

Description: Fraction of capital invested in agriculture allocated to the devlopment of arable land

arable_land

Type: MassInPort

Description: Arable land

marg_prod_agr_inp

Type: MassOutPort

Description: Development of marginally producing land

land_yield

Type: MassOutPort

Description: Land yield

population

Type: MassInPort

Description: Population

yield_tech_LYTD

Type: MassInPort

Description: Technology induced absolute yield enhancement

land_fertility

Type: MassInPort

Description: Land fertility

s_yield_mlt_air_poll

Type: MassInPort

Description: Land yield multiplier from air pollution

food_ratio

Type: MassOutPort

Description: Food ratio

tot_agric_invest

Type: MassOutPort

Description: Total investment in the agricultural sector

agr_inp_per_hect

Type: MassOutPort

Description: Agricultural investments per hectare

s_fioa_agr

Type: MassOutPort

Description: Fraction of total investments allocated to the agricultural sector

p_fr_inp_for_land_maint

Type: MassOutPort

Description: Fraction of investments in the agricultural sector allocated to land maintenance

yield_tech_mult_icor_COYM

Type: MassOutPort

Description: Technology induced relative enhancement of land yield

food_pc

Type: MassOutPort

Description: Per capita annually consumed food

Components (30)

P_Indic_Food_PC_1

Type: Tabular

Description: p.286 of Dynamics of Growth in a Finite World

P_Indic_Food_PC_2

Type: Tabular

Description: p.286 of Dynamics of Growth in a Finite World

S_Indic_Food_PC

Type: S_Indic_Food_PC

Description: p.286 of Dynamics of Growth in a Finite World

P_Fr_IO_Al_Agr_1

Type: Tabular

Description: p.287 of Dynamics of Growth in a Finite World

Div1

Type: Division

P_Fr_IO_Al_Agr_2

Type: Tabular

Description: p.287 of Dynamics of Growth in a Finite World

S_FIOA_Agr

Type: S_FIOA_Agr

Description: p.287 of Dynamics of Growth in a Finite World

Tot_Agric_Invest

Type: Prod_2

Description: p.287 of Dynamics of Growth in a Finite World

Source1

Type: Source

Chg_Agr_Inp

Type: Rate_1

Agr_Inp

Type: Level1a

Ch_Agr_Inp

Type: Ch_Agr_Inp

Description: p.292 of Dynamics of Growth in a Finite World

Current_Agr_Inp

Type: Current_Agr_Inp

Description: p.292 of Dynamics of Growth in a Finite World

S_Avg_Life_Agr_Inp

Type: S_Avg_Life_Agr_Inp

Description: p.293 of Dynamics of Growth in a Finite World

P_Fr_Inp_For_Land_Maint

Type: Tabular

Description: p.332 of Dynamics of Growth in a Finite World

Source2

Type: Source

Chg_Perc_Food_Ratio

Type: Rate_1

Perc_Food_Ratio

Type: Level1a

Agr_Inp_Per_Hect

Type: Agr_Inp_Per_Hect

Description: p.294 of Dynamics of Growth in a Finite World

Marg_Land_Yield_Mlt_Cap

Type: Tabular

Description: p.313 of Dynamics of Growth in a Finite World

Land_Yield_Mlt_Cap

Type: Tabular

Description: p.306 of Dynamics of Growth in a Finite World

Land_Yield

Type: Prod_4

Description: p.307 of Dynamics of Growth in a Finite World

Marg_Prod_Agr_Inp

Type: Marg_Prod_Agr_Inp

Description: p.313 of Dynamics of Growth in a Finite World

Food

Type: Food

Description: p.280 of Dynamics of Growth in a Finite World

Food_PC

Type: Division

Description: p.281 of Dynamics of Growth in a Finite World

Food_Ratio

Type: Gain

Description: p.332 of Dynamics of Growth in a Finite World

Ch_Perc_Food_Ratio

Type: Ch_Perc_Food_Ratio

Description: p.333 of Dynamics of Growth in a Finite World

S_Land_Yield_Fact

Type: S_Land_Yield_Fact

Description: p.307 of Dynamics of Growth in a Finite World

P_Land_Yield_Fact_2

Type: SMTH3

Yield_Tech_Mult_Icor_COYM

Type: Tabular

Used in Examples (11)

Scenario_11

SystemDynamics.WorldDynamics.World3

Influencing the future 10 years later

Scenario_10

SystemDynamics.WorldDynamics.World3

Influencing the future 20 years earlier

Scenario_9

SystemDynamics.WorldDynamics.World3

Combining the measures of Scenarios #6 and #8

Scenario_8

SystemDynamics.WorldDynamics.World3

More abundant non-recoverable natural resources, birth control, and stable industrial output

Scenario_7

SystemDynamics.WorldDynamics.World3

More abundant non-recoverable natural resources and birth control

Scenario_6

SystemDynamics.WorldDynamics.World3

More accessible non-recoverable natural resources, pollution control, land yield enhancement, erosion protection, and resource efficiency

Scenario_5

SystemDynamics.WorldDynamics.World3

More accessible non-recoverable natural resources, pollution control, land yield enhancement, and erosion protection

Scenario_4

SystemDynamics.WorldDynamics.World3

More accessible non-recoverable natural resources, pollution control, and land yield enhancement

Scenario_3

SystemDynamics.WorldDynamics.World3

More accessible non-recoverable natural resources and pollution control

Scenario_2

SystemDynamics.WorldDynamics.World3

More abundant non-recoverable natural resources

Scenario_1

SystemDynamics.WorldDynamics.World3

Original WORLD3 model