The CLASSES Model

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The CLASSES Model

• Overview
• January 15-19, 2007

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CLASSES Model Purpose

• To understand the interactions between soil,
  livestock and economic dynamic processes and
  farmer welfare
• To examine possible interventions from economic
  and biophysical perspectives to improve farmer
  welfare

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Model Setup and Feedback

• Initialization household has 10 patches with
  either food, cash or napier, has some or no
  livestock (each patch0.1 ha)
• Initialization Survey data are used to calculate
  expected value of labor in food crops, cash
  crops (tea), napier, livestock
• At time 0 Crop(s) start to grow, animals are
  fed, household cash is spent on soil amendments,
  labor etc.

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Model Setup 2

• Every quarter any fully grown food crops are
  harvested (napier and tea have continuous
  harvesting), nutrients extracted from soil,
  farmer sells output.
• Every quarter farmer updates the expected value
  of labor in each activity, reallocates land into
  highest return activity, invests or disinvests in
  livestock
• Every quarter new soil quality determines crop
  growth and cycle begins again

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Major Feedback Loops
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Introduction to Vensim

• Will show how to use Vensim to create models
• Will show where to get help/find out more about
  Vensim capabilities

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Livestock Submodule

• Household can buy, sell and maintain livestock
• Cows in herd produce milk and are bred for
  several cycles
• Investment HH purchases livestock if it has
  sufficient cash, feed and labor resources
• Disinvestment HH sells male calves, plus animals
  that are in poor health. HH can also sell if
  there is a feed or cash shortfall

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Major Feedback Loops
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Main Livestock Model Views

• Herd Structure
• Shows aging of animals, investment and
  disinvestment, calves (7 classifications of
  animal)
• Milk Production
• calculates milk production for feeding to calves
  and for sale, also sums up Total Livestock Units,
  cumulative sales
• Nutrient Requirements
• Shows desired and actual amounts fed for all
  types of animal (5 feed classifications), in
  terms of amount of feed and energy requirements

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Main Livestock Views 2

• Crop Residues
• Shows management of crop residues for feeding to
  herd, calculates amount available for
  incorporation as green manure
• Body Condition Score
• Tracks the body fat content of each class of
  animal and calculates overall body condition
  score
• Scores less than 1.5 induce sales
• Manure
• Shows overall manure produced by herd, plus
  amount of Nitrogen and Phosphorus content

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Crop/Soils Submodule

• Household manages 10 land patches (0.1 ha)
• patches are in maize, napier or tea
• Investment Crop choice determined by max average
  value product of labor
• AVP(Priceoutput)/Labor input
• Crop extract N and P from the soil
• N and P can be added to soil
• with manure, fertilizer or soil organic matter

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Crop/Soils Submodule 2

• Soil Organic Matter Minerals in soil become more
  or less available to plants due to various
  physical processes
• Food Crops Harvested every other quarter, with
  seasonality of output
• Napier Continuous harvesting
• Tea Continuous harvesting

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Major Feedback Loops
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Main Crop/Soil Views

• Organic Matter Flows Soil organic matter
  (carbon) flows between different kinds of
  availability
• Can add green manure to augment Free Soil organic
  matter stock
• There are outflows to the atmosphere (i.e. not
  all carbon is conserved)

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Main Crop/Soil Views 2

• Phosphorus Flows Tracks the phosphorus content
  of the soil organic matter
• has additional stocks for soluble phosphorus that
  is used in crop growth
• There is some proportion of phosphorus that is
  non-soluble
• Can add phosphorus with Fertilizer (DAP) and
  Manure

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Main Crop/Soil Views 3

• Nitrogen Flows Tracks nitrogen content of soil
  organic matter
• has two forms of soluble nitrogen for crop uptake
• Can add nitrogen with Fertilizer (DAP, Urea) and
  Manure
• Tea crops are assumed to add Nitrate directly
  (and is available upon undertaking tea
  cultivation from Tea Buyer)

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Main Crop/Soil Views 4

• Crop Growth Shows Biomass yield as a function of
  the Efficiency of uptake of N and P
• Yield is N or P limited (i.e. which ever is
  minimal in soil will determine crop yield)
• Yields are calibrated to a reference crop yield,
  based on data from new forest conversions
• Harvest Index
• 50 for maize, 100 all others

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Economic Submodule

• Household makes Livelihood Decisions over crop
  choices and investment/disinvestment in livestock
  based on AVP
• HH allocates available land, cash and labor force
  to either maize, tea, napier or livestock
  activities
• Land is endowed (no land market)
• Cash from ag. receipts, off-farm, other sources
• Labor is household members plus any hired in,
  minus any hired out

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Major Feedback Loops
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Main Economic Views

• Land allocation Tracks state of patches in terms
  of crop choice
• Also keeps track of time since establishment for
  perennials (i.e. there is a delay in production)
• Also has info on crop specific harvest times

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Main Economic Views 2

• Production/Consumption Norms Calculated from
  data
• average labor usage, costs per livelihood
  activity
• average maize consumption per household
• Effective Market Prices accounts for
  transactions costs in maize/labor markets

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Main Economic Views 3

• Crop Harvest Calculations sums up total
  production by crop type overall patches
• Harvests are adjusted by any labor shortfalls
• Labor Force Allocation Household allocates labor
  resources by activity priority (given by AVP) and
  availability
• Average hours worked per day and labor in a given
  activity calculated from data

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Main Economic Views 4

• Off Farm Labor Household can hire labor in or
  out, depending on cash availability/shortfalls
• Cash Allocation Household allocates available
  cash to different livelihood activites based on
  priority (given by AVP)
• Household earns cash receipts from agricultural
  sales, off-farm income, remittances, gifts etc.

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Main Economic Views 5

• Returns to Labor Where AVP is calculated
• Labor used taken from labor allocation view,
  output from Crop/Soils submodule, prices averaged
  from data
• AVP of Livestock given by the AVP of Milk
  Production

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Main Economic Views 6

• Decisions Livelihood activity ranking (from AVP)
  and Feasibility are evaluated
• Investment occurs when ranking is high and
  activity is feasible from land, cash, labor
  standpoint
• Decisions made every quarter about Land
  Allocation, Livestock acquisition
• Livestock sales can occur at any time

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Policy Evaluation Exercises

• Each group will study a farm with a different
  initial endowment of activities
• Pure Maize Farm (no livestock)
• Pure Tea Farm (no livestock)
• Mixed Maize, Napier and 1 Heifer
• Mixed Maize and Tea Farm (no livestock)

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Levers to Analyze

• Green Manure
• Fertilizer (purchased from farmers own cash
  stock)
• Quarterly Remittances
• Price Changes

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Various Outcome Variables

• Pick 3 or 4 Outcome variables from the 9
  possibilities
• Evaluate the impact of the Lever over the base
  case
• Prepare a short (10 minute) presentation on your
  findings

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Note about Subscripts

• The professional version of Vensim can use a tool
  called Subscripts to track multi-dimensional
  vectors over time
• Example The farmers have 10 plots. The soil
  dynamics of each of these is subscripted by
  PatchNumber
• This allows construction of models without having
  to replicate model structure multiple times
• i.e. would not want to replicate soil structure
  10 times, one for each patch!!!

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Note about Subscripts 2

• For the policy exercise, it will be easiest to
  conduct your analysis on the first patch
• Therefore, subscript N1 has been selected for
  you
• However, be aware that the dynamics are different
  for different patches