APSIM Agricultural Production Systems Simulator Mehrnoosh
Eghtedari Decamber 2013 1 Slide 2 Introduction APSIM: is a modeling
environment that uses various component modules to simulate
cropping systems in the semi-arid tropics. Modules can be
biological, environmental, managerial or economic and are linked
via the APSIM "engine". can simulate the growth and yield of a
range of crops in response to a variety of management practices,
crop mixtures and rotation sequences, including pastures and
livestock. 2 Slide 3 Goals of APSIM To simulate of biophysical
processes in farming systems. To assist the search for better
farming strategies and the development of aids to better production
decision making under risk. To require a tool to accurate
predictions of crop production in relation to climate, genotype,
soil, and management factors regarding long term management of
resources. 3 Slide 4 History of APSIM Commonwealth Scientific and
Industrial Research Organisation In the early 1990s. 4 Slide 5
Capabilities of APSIM Growth and yeild simulation of more than 25
crops. Growth and biomass simulation of pastures. Growth and
biomass simulation of trees. Crop Competition with weeds
simulation. Weed population dynamics. 5 Slide 6 Capabilities of
APSIM Intercropping systems simulation. Systems simulation in
irrigated and rainfed conditions. The impact of management factors
simulation. (Tillage, Irrigation, Fertilizing, Date of sowing)
Rotation and fallow simulation. 6 Slide 7 Capabilities of APSIM
Agroforestry systems simulation. Key processes simulation in the
soil. Carbon decomposition and surface residues simultion. Systems
simulation in various scales (gene to ecosystem). The effect of
climate change simulation. Production socio-economic effects
simulation. 7 Slide 8 Combining with Different Models CABALA: A
model for predicting forest growth 8 Slide 9 The APSIM Model
Framework A set of biophysical modules that simulate biological and
physical processes in farming systems, A set of management modules
that allow the user to specify the intended management rules.
Various modules to facilitate data input and output to and from the
simulation. A simulation engine that drives the simulation process
and controls all messages passing between the independent modules.
9 Slide 10 STRUCTURE of APSIM ( Mathematical-Mechanistic-
Dynamic-Code based ) Manag er ClockReport Met SoilWat SoilN SoilPH
SoilP Erosion Manure Residue Economics Manager Fertilize Irrigate
Other Crops Legume Sorghum Maize Canopy Wheat System Control
Climate Soil Management Crops 10 Slide 11 APSIM Modules Crop Soil
Climate Mangement System Control 11 Slide 12 Crop Modules APSIM
contains an array of modules for simulating growth, development and
yield of crops, pastures and forests and thier interactions. The
plant modules simulate key physiological processes and operate on a
daily time step in response to input daily weather data, soil
characteristics and crop management actions. All plant species use
the same physiological principles to capture resources and use
these resources to grow. The main differences are the thresholds
and shapes of their response functions. 12 Slide 13 Crop Modules
Crop ontogeny is simulated via relationships defining responses to
temperature and photoperiod. Leaf area production and senescence is
simulated via relationships of leaf initiation rate, leaf
appearance rate and plant leaf area with temperature. Potential
crop water uptake is simulated via relationships with root
exploration and extraction potential, which depends on soil and
crop factors. 13 Slide 14 Crop Modules All coefficients for general
crop responses and crop/cultivar specific coefficients are stored
external to the code to allow ease of use and transition across
crops/cultivars. Constants and parameters from the code are stored
in crop parameter files. Each file consists of two major parts:
crop-specific constants and cultivar-specific parameters. 14 Slide
15 Physiology of Yield Formation Climate Soil Mangement Yield Dry
Matter Light Interception Leaf Area Phenology C k RUE HI 15 Slide
16 Physiology of Yield Formation 16 Harvest Index Dry Matter= Yield
HI = f(phenology, temperature, water,nutrients, management) HI
(Grain Number x Grain size )/Dry Matter Linear function of biomass
accumulation after anthesis Slide 17 Crop Modules AgPasture Growth
PlantCropsSlurpCanopy 17 Slide 18 Crop Submodules AgPasture : A
pasture growth model, Based on the physiological model of Thornley
& Johnston (2000), Designed for the simulation of mixed
pastures of C3 and C4 grasses and legumes, Requirement: Micromet,
Soil (SoilN and SoilWat or SWIM), Surface Organic Matter
(SurfaceOM) and Fertiliser, and optionally Irrigation and pasture
Managers. 18 Slide 19 Crop Submodules Canopy (Intercropping):
Simulates light and water competition between crops, On a daily
basis, finds the number of crops in the simulation and their canopy
heights, Canopy layers are then defined, with the layer boundaries
being defined by the top of each canopy. Thus there are as many
layers as canopies. 19 Slide 20 Crop Submodules Canopy
(Intercropping): Then each layer in turn is taken from the top, in
the combine canopy, to get the combined (extinct_coeff * LAI) value
of the canopies present in that layer. The fraction of light
transmitted out of the bottom of that layer can be calculated. The
total radiation intercepted in a layer is divided amongst the
canopies occupying the layer, being done on the basis of
(extinct_coeff * LAI) of each canopy. 20 Slide 21 Crop Submodules
Canopy (Intercropping): LAI is distributed with height in the
canopy using normalized height and integration of a specific
function. This results in 47% of the leaf area in the top 10% of
height, 27% in the next 10%, 15% in the next 10%, and so on. 21
Slide 22 Crop Submodules Growth: A simplified plant growth module
developed for simulating pasture and forestry systems module. Major
classes of biomass pools: 1.Growth pool responsible for most growth
processes 2.Structural pool provides sinks for assimilate and
nutrients and are used to describe plant properties such as plant
height. 22 Slide 23 Crop Submodules Growth: Growth Calculation: :
Daily Growth : Daily intercepted solar radiation (MJ/m2) : The
light use efficiency (g/MJ) : Growth modifiers for temperature :
Growth modifiers for nitrogen : Growth modifiers for vapour
pressure deficit : Soil water supply 23 Slide 24 Crop Submodules
Growth: variation in root:shoot ratio Partitioning structural
fraction of above-ground growth 24 Slide 25 Crop Submodules Plant :
Simulates the growth of a number of different species on a daily
time-step (on an area basis not single plant). Plant growth in this
model responds to climate (temperature, rainfall and radiation from
the Met module), soil water supply (from the Soilwat module) and
soil nitrogen (from the SoilN module). 25 Slide 26 Crop Submodules
Slurp: a model for calculating soil water uptake by plants. Inputs
: a)plant root ( root length profile and extraction potential ) b)
canopy (live LAI, dead LAI, extinction coefficients and canopy
height) 26 Slide 27 Crop Modules Crops 27 Slide 28 Crop Modules
Crops 28 Biomass accumulation 1.Water-nonlimiting dlt_dm_rue = RUE
*radiation_interception (1) 2.Water-limiting dlt_dm_water = soil_
water_ supply * transpiration_efficiency (2) dlt_dm =
min(dlt_dm_water, dlt_dm_rue) Slide 29 Soil Submodules Eroison
Daily soil erosion, and its effect on the soil profile Map It maps
simulation soil layers onto output layers SoilN The dynamics of
both carbon and nitrogen in soil SoilP The availability of
phosphorus in soil SoilTemp Soil temperature 29 Slide 30 Soil
Submodules SoilWat The soil water balance model Solute Solute
balance model Surfac Surface water conductivity changes with time
SurfaceOM The effect of surface organic matter SWIM Infiltration
and water movement in soil WaterSupply The role of water-source for
the Irrigate module 30 Slide 31 Soil Erosion Module Sub model 1:
Freebarin E: Event soil loss (t/ha) COV: Cover (%) Q: Event runoff
(mm) K: Soil erodibility factor LS: Slope length and steepness
factor P: Supporting practice factor Sine of slope angle Length of
catchment (m) 31 Slide 32 Soil Erosion Module Sub model 1: Rose E:
Event soil loss (t/ha) S: Sine of slope angle cov: Fractional
surface cover (0-1) Q: Event runoff (mm) : Factor approximating
efficiency of entrainment bare : Efficiency of entrainment (bare
surface) COV: Surface cover (%) 32 Slide 33 SoilN Module FOM -
fresh organic matter (crop residues, dead roots) BIOM the more
labile, soil microbial biomass HUM the bulk of soil organic matter
33 Slide 34 SoilN Module Decomposition of Soil Organic Matter Pools
34 Slide 35 SoilTemp Module Air temperature depth thermal
conductance boundary layer heat storage temperature number of nodes
annual average soil temperature Method: 1- Heat storage in nodes 2-
Resistance to heat transfer in layers 35 Slide 36 SoilWat Module
The Water Balance INPUT = OUTPUT 36 Slide 37 SoilWat Module Methods
of water movement Cascading Layer Richard s equation Daily time
step 37 Slide 38 SoilWat Module The thickness of each layer by the
user 100 or 150 mm the uppermost layer 300 or 500 mm the base of
the profile The whole profile by up to 10 or more layers 38 Slide
39 SoilWat Module Processes represented in SOILWAT, adapted from
water balances such as WATBAL and CERES, include: Runoff: USDA
curve number (CN) runoff model, include effect of : a.soil water
content b. soil cover both from crop and crop residue c.roughness
due to tillage Evaporation: based on potential evaporation
(Priestly/Taylor or Penman/Monteith) 39 Slide 40 SoilWat Module
Saturated flow : Sw i+1 = Sw i+1 + SWCON i x (SW i - DUL i ) for
layer i, SW i > DUL i Unsaturated flow : Between LL and DUL,
water can move between layers in proportion to the water content
gradient. Movement of solutes associated with saturated and
unsaturated flow of water are calculated using a mixing algoritm.
40 Slide 41 Met Module The APSIM Met module provided daily
meteorological information to all modules within an APSIM
simulation. 41 Slide 42 Management Module Fertilizer Effect of
fertilizer application on a system Irrigation Irrigation scheduling
Economics Maintains a cash balance through the simulation, which
monitors all financial activity (e.g. income, expenses, loan
repayments). 42 Slide 43 System Control Manager Capability to
specify a set of rules using conditional logic during simulations
to control the actions of modules. Clock Simulation time Report
Creates a columnar output file to record data from an APSIM
simulation. 43 Slide 44 44
