N-flow in Danish agriculture And FarmAC in Amazonas Ib Sillebak Kristensen & Nick Hutchings Aarhus University Dept. of Agroecology Foulum. Denmark 10. Feb Campinas, Brazil.

part 1 Principles for Nutrient flows, examplified on average DK agriculture

Farm N balance & N-leaching Hansen et al. Env Sci. Tech. (2011)

N-eff. in Danish Agriculture

Danish Farm N surplus Development and Variation Dalgaard et al. BiogeoSciences 9 (2012)

N-flow on 4 organic dairy farms in Estonia in N/cow in manure from stable

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 = 112

Farm-balance: Reliable Field-balance: Un-secure 9

N-losses in DK-agriculture, 1999 Kg N ha -1 year -1 % N-los of input Farm gate N-surplus125 Amm. los in: -Stall -9 9 % -Storage -4 4 % Field N-surplus112 Amm. los: -Spreading -811 % -Grazing -1 7 % -Fertiliser -5 3 % -Crops -4 4 % Denitrifikation % Change in soil-N 0 N-leaching (=difference) - 78

,000,501,001,502,00 N/ha LU/ha - Farmgate N balancer on arable sandy soil SvinKonv. mælkØko. mælkØko. PlanteKonv. plante Arable conv. Arable organic Dairy organic Dairy conv. Pig conv.

FarmAC model – the basics

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

17 Deposition Fixation Fertiliser Manure NH 3, N 2 O Exported NH 3, N 2 O NH 3,N 2 0,N 2 NH 3, N 2 O NH 3,N 2 0,N 2 NO 3 3 NH 3, N 2 O NH 3,N 2 0,N 2 NH 3, N 2 O Exported NH 3, N 2 O Exported NO 3 Runoff NH 3, NO Storage losses

18 NO 3 Runoff NH 3, N 2 O Exported Fertiliser Manure NO 3 CO 2 NH 3, N 2 O CH 4,CO 2 NH 3, N 2 O CH 4,CO 2 NH 3, N 2 O CH 4,CO 2 NH 3, N 2 O Exported NH 3, N 2 O Exported NH 3, NO Storage losses

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

1 st product (e.g. grain) 2 nd product (e.g. straw) (may or not be harvested) above-ground crop residue root + leaf scenescence How the model sees grain crops

Grazed forage root + leaf scenescence Ungrazable residue root + leaf scenescence Ungrazable residue Unutilised forage Grazed forage How the model sees forage crops

Enough production More than enough production Grazed yield Unutilised (residue) Ungrazable residue Modelled yield Grazed yield Ungrazable residue Modelled yield

Grazed yield Ungrazable residue Modelled yield Deficit! Not enough production What the pasture can supply What the cattle thinks they can eat

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

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

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

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

Calculating mineral N available N outputs –Ammonia emission, which varies between fertiliser, manure, urine application method –N 2 O and N 2 emission N 2 O via emission factor (varies between sources) N 2 = N 2 O * factor –N leaching, which varies with timing of application of fertiliser/manure Period with drainage

Growth Potential crop N uptake = crop N uptake with water-limited yield If mineral N available >= potential crop N uptake –Modelled growth = water-limited growth Otherwise –Modelled growth = mineral N available/potential crop N uptake

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

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

Forest Quick degradeble ½ time life =1,5 mdr degradeble ½ time life =5 year Slow degradable ½ time life = 365 years Total soil-C

Bare soil

Grass – no cattle

Grass – few cattle

Grass – more cattle

N inputs – light grazing

N outputs – light grazing

C stored in soil – long term

Dry matter production – long term

N inputs long term

N outputs long term

Losses are calculated for the whole crop period

So it might be sensible to divide the crop in two

Soil-C in farm type År C (t/ha) DK dairy Pig Arable

Soil pools never in equilibrium