N-flow%20in%20Danish%20agriculture%20And%20FarmAC%20in%20Amazonas

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N-flow in Danish agricultureAnd FarmAC in
Amazonas

• Ib Sillebak Kristensen Nick Hutchings
• Aarhus University
• Dept. of Agroecology
• Foulum. Denmark
• 10. Feb. 2015. Campinas, Brazil.

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part 1

• Principles for Nutrient flows, examplified on
  average
• DK agriculture

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Farm N balance N-leaching
Hansen et al. Env Sci. Tech. (2011)
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N-eff. in Danish Agriculture
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Danish Farm N surplusDevelopment and Variation
2008
1990
Dalgaard et al. BiogeoSciences 9 (2012)
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N-flow on 4 organic dairy farms in Estonia in 1998
75N/cow in manure from stable
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• DK agriculture N-balance, 1999
• Input Kg N ha-1 year-1
• N-fertiliser 94
• Seed 2
• Fodder 79
• N-fixation 13
• Precipitation 16 
• Output
• Milk -9
• Animals -28
• Cash crops -41 
• los in .
  
• 
  -stall -storage fieldbalance
• N-surplus 125 - 9 -4 112

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Field-balance Un-secure
Farm-balance Reliable
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• N-losses in DK-agriculture, 1999
• Kg N ha-1 year-1
  N-los of input
• Farm gate N-surplus 125
• Amm. los in
• Stall -9 9
• Storage -4 4
• Field N-surplus 112
• Amm. los
• Spreading -8 11
• Grazing -1 7
• Fertiliser -5 3
• Crops -4 4
• Denitrifikation -16 11
• Change in soil-N 0
• N-leaching (difference) - 78

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Dairy conv.
Pig conv.
Dairy organic
Arable organic
Arable conv.
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FarmAC model the basics
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FarmAC model

• Focusses on livestock farming systems
• Can be used for arable agriculture
• Intended to have wide applicability
• Simple enough that demand for inputs and
  parameters is manageable
• Complex enough to describe consequences of
  mitigation/adaptation measures
• Mass flow for C and N
• Consistency between GHG and N emissions
• Capture knock-on effects

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Components

• Cattle model (simplified Australian)
• energy and protein determine growth/milk
• Animal housing and manure storage (mainly IPCC)
• Crop model
• Potential growth N limitation water
  limitation
• Soil model
• simple soil water model
• simple soil C and N model

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How the model sees grain crops
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How the model sees forage crops
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Enough production
More than enough production
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What the cattle thinks they can eat
What the pasture can supply
Not enough production
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Running FarmAC (1)

• Define crop sequences
• area, soil type, irrigation
• crop sequence (crops and bare soil)
• Define yield potentials and grazed yields
• also define fate of crop residues
• Define livestock numbers, feed rations, livestock
  housing and manure storage
• calculates manure production
• calculates livestock production
• Decide manure and fertiliser applications

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Running FarmAC (2)

• Simulate!
• What can go wrong
• grazed yield cannot be achieved
• total production of grazed forage does not equal
  total consumption of grazed forage

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Yield modelling

• Potential yield (water and N unlimited)
• for all crop products
• input by users
• Calculate water-limited yield (Water balance)
• Calculate N uptake at water-limited yield
• includes N in above and below-ground crop
  residues
• Calculate mineral N available
• Mineral N or maximum uptake determines yield

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Calculating mineral N available

• Mineral N mineral N input - losses
• N inputs
• atmosphere
• N fixation
• fertiliser
• manure
• urine
• mineralised soil, manure organic N, dung and crop
  residue N

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Calculating mineral N available

• N outputs
• Ammonia emission, which varies between
• fertiliser, manure, urine
• application method
• N2O and N2 emission
• N2O via emission factor (varies between sources)
• N2 N2O factor
• N leaching, which varies with
• timing of application of fertiliser/manure
• Period with drainage

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Growth

• Potential crop N uptake crop N uptake with
  water-limited yield
• If mineral N available gt potential crop N uptake
• Modelled growth water-limited growth
• Otherwise
• Modelled growth mineral N available/potential
  crop N uptake

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How to define a permanent crop

• The fertilisation necessary to achieve a given
  yield will change with time
• For grazed crops, the fertilisation will be
  determined by the year with the least
  mineralisation of soil N
• Means that excessive fertiliser will be applied
  in other years
• Break the permanent crop into several crops

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Amazonian forest

• Simulated here by teak
• Main features
• no export of products
• deep roots, high rainfall 1000 mm drainage and
  high temperature
• high CN ration in residues
• N input 10 kg/ha/yr from precipitation

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Forest
Total soil-C
Slow degradable ½ time life 365 years
degradeble ½ time life 5 year
Quick degradeble ½ time life 1,5 mdr
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Bare soil
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Grass no cattle
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Grass few cattle
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Grass more cattle
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N inputs light grazing
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N outputs light grazing
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C stored in soil long term
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Dry matter production long term
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N inputs long term
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N outputs long term
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Losses are calculated for the whole crop period
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So it might be sensible to divide the crop in two
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Soil-C in farm type
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Soil pools never in equilibrium