Outline presentation

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Outline presentation

• Discussion on last session
• PPC concept and use in Agroforestry
• Optimal crop combination
• Tree crop interactions
• conclude

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Production Possibility Curve

• A production possibility curve is the local of
  the combinations of forest and agricultural
  products that can be obtained with a given amount
  of resources. Such curves are also called
  iso-cost curves, production transformation curve
  or production possibility frontier.

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Production Possibility Curves (PPC)

• The product relations in Agro-forestry can be
  explained with PPCs which also help to determine
  the optimal combination for profit maximisation
  in Agro-forestry.

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Product relations in Agro-forestry

• Three types of relationships in Agro-forestry
  explain the trees and agriculture crop
  intercropping as follows
• Complementary
• Supplementary
• Competitive

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Complementary

• 1. Complementary is a synergistic or symbiotic
  type of relationship between the two crops and
  intercropping results in increased production for
  both of the crops. e.g., wind break/ shelter belt
  synergistic e.g., bee keeping (apiculture) in
  horticulture farm, Cardamom - Alnus nepalensis.

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Supplementary

• 2. Supplementary is a type of relationship where
  the intercropping results into increased of
  production for one crop while the production of
  another crop remains unchanged. For example if
  agriculture and tree crops are intercropped,
  production of agriculture crop increases while
  the tree crops remains unchanged or vice versa.
  Taungya gives good example of supplementary
  relationship.

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Competitive

• 3. Competitive is the relationship where the
  production of agriculture crop decreases with
  increased tree crops e.g.,Tea with Albezzia
  yielded less than with other shade trees (Willey,
  1975).

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Production Possibility Curves
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Optimal crop production

• Yield of tree crop

Yt
Yield of agriculture crop
Ya
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Optimal crop production

• The optimal crop combination from financial
  point of view depends on production relationship
  and price ratio of forest products to
  agricultural crops. The combination is the point
  where PPC is tangent to the price line. If the
  price ratio changes the optimal combination also
  changes.
• PPC convex to origin results in either
  agriculture or forestry. A PPC concave to origin
  is favourable for agroforestry. Specialisation
  might occur if price line is either steep or
  flat, and in such cases agroforestry is only
  practiced if strong complementary or
  supplementary relations exist.

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Tree crop interactions
Agroforestry systems Positive Negative
1. Perennial crop with trees Complementary Competitive-water/nutrients/shade
2. Trees intercropped - agriculture crops Complementary Competitive-water/nutrients/shade
3. Alley planting Complementary Competitive-water/nutrients/shade
4. Contour planting Increased production through soil protection and organic matter contribution. Competitive -water/nutrients/shade
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5. Wind break Increased production through protection from winds crop production helps to cover cost of plantation establishment. Competitive-space/water/nutrients.
6. Taungya Crop production helps to cover cost of plantation establishment. Shade and competition eliminate crop production in 3-4 years.
7. Woodlot Isolate trees from crops, avoiding potential negative tree-crop interaction Competition for crop production area, poor matching of species to site and poor management can increase soil erosion

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Tree-crop interaction continued
8. Home garden Generally does not compete for crop production area. There is no tree-crop interface, little interaction.
Source Current et al., 1995. Source Current et al., 1995. Source Current et al., 1995.
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• Optimum crop production depend both on production
  relationship and price ratio of forest crop to
  the agriculture crop. Optimum crop production is
  the point in PPC that is tangent to the price
  line.
• In the optimum point the value of marginal
  product also called the marginal value product of
  the resource in forestry is equal to that of the
  agriculture.

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• PPC concave to the origin will promote
  agro-forestry if both crops have value but PPC
  convex to the origin promotes specialisation or
  monoculture. But even if PPC is concave
  specialisation or monoculture will prevail if the
  price line is very steep or flat. Hence if the
  price line changes, optimal combination of tree
  and agriculture crops also changes

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Agro-forestry tools

• Land Equivalent Ratio (LER)
• m
• LER S yi/yii - - - - - - - - - - - - (a)
• i1
• yi yield from the intercropped area
• yii- yield from sole cropping.
• In formula (a) If LER gtor lt1, then the yield in
  intercropping exceeds or is smaller than that of
  the sole cropping, rejecting or accepting
  intercropping.

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• However LER has weakness due to localised
  measures of biological productivity. It is
  because the effects of total plant density and
  the density of one plant on the other are
  compounded (Trenbath, 1976 as cited by
  Ranganathan et al., 1991). In order to overcome
  the weakness of LER, Ranganathan (1991) proposed
  Yield Advantage Index (YAI).

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Thought of the day

• Leuceana is planted on field boundaries and
  seldom interspersed with field crops.
• (Leuceana with sorghum/pigeon pea hedgerow
  intercropping is economically inferior than sole
  planting (ICRISAT experiments) gives convex
  curve. The finding was in consistence with
  intercropping practices in that region)

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• THANKS