The effects of conversion to organic farming on N leaching are discussed in the presentation. Problems in European aquatic environment are presented along with the development of organic farming in Denmark and the rest of Europe. Recent Danish studies on the N leaching effects by conversion of mixed dairy and arable farms are presented. The studies estimate that N leaching is lower from organic compared to conventional mixed dairy farms, whereas N leaching at organic arable farms are comparable to conventional arable farms

Knudsen, Marie Trydemann

Kristensen, Erik Steen

English

Knudsen, Marie Trydeman

Copenhagen University Research Information System

Impact of Organic farming on aquatic environment

Organic Eprints

DARCOFPresentation in  Presentation in Lednice Lednice 1 1st st July 2004 July 2004Impact of Organic farming on aquatic environment  Impact of Organic farming on aquatic environment By ByErik Steen  Erik Steen Kristensen Kristensen and Marie  and Marie Trydeman Trydeman Knudsen KnudsenDanish Research Centre for Organic Farming  Danish Research Centre for Organic Farming ( (www.DARCOF.dk www.DARCOF.dk) )DARCOF (Danish Research Centre for OrganicFarming) DARCOFPresentation of DARCOF• Established in 1996 by the government • Initiate and coordinate R & D in organic agriculture• Communicate the results and contribute to further education • “Centre without walls”: 20 Institutes, 140 Scientists• 30-50 research projects, 40-60 mill Dkr (5-8 mill €) per yearDARCOFOutline1. Problems in European aquatic environment2. Development in organic farming3. Effect of conversion to organic mixed/dairy farming4. Effect of conversion to organic arable farming5. ConclusionNitrate concentration in European riversSource: European Environment Agency (http://dataservice.eea.eu.int/atlas/viewdata/viewpub.asp?id=546)Development since 1955Extension 1994-96Nitrate in groundwaterSource: European Environment Agency (http://dataservice.eea.eu.int/atlas/viewdata/viewpub.asp?id=110)European Environment Agency, 2003Nitrate Vulnerable ZonesSource: European Environment Agency (http://dataservice.eea.eu.int/atlas/viewdata/viewpub.asp?id=150)Phosphorus concentration in European rivers og lakesSource: European Environment Agency (http://dataservice.eea.eu.int/atlas/viewdata/viewpub.asp?id=546 )Rivers (1994-96) Lakes and reservoirsEuropean Environment Agency, 2003Indicators AssessmentsNitrate in groundwaterNo decrease (or increase) in levels of nitrate in Europe’s groundwater.Nitrate drinking water limit values exceeded in one third of the groundwater bodies.Nitrate in drinking water a common problem across Europe.Nutrients in riversConcentrations of phosphate have decreased in the rivers of the EU and accession countries during the 1990s.Nitrate concentrations in rivers stable throughout the 1990s - highest in western Europe where agriculture is most intensive.Phosphorus in lakesEutrophication of European lakes is decreasing.Still many lakes and reservoirs with high concentrations of phosphorus - highest in accession countries.Nutrients in marine watersNutrient concentrations in Europe’s seas have generally remained stable over recent years.Status of European watersDARCOFOutline1. Problems in European aquatic environment2. Development in organic farming3. Effect of conversion to organic mixed/dairy farming4. Effect of conversion to organic arable farming5. ConclusionDARCOFDevelopment of organic farming in EU-15 countrieshttp://www.organic.aber.ac.uk/stats.shtml020000400006000080000100000120000140000160000180000198819901992199419951996199719981999200020012002Total hectares010002000300040005000600070008000Number of farmsHectares FarmsDevelopment of organic farming in DenmarkOrganic farms in Denmark 2003110Others1542Clover/ grass0,65 25 19 2400 Others (incl.  pigs/poultry)5 10 590,07 25 83 530 Arable farms13 28 15 1,28 50 115 770 Mixed/dairy farms6,4 178.000 48 3700 Organic, totalPerma-nentgrassSilage(maize + pea/barley)Cereals,maturityLive-stockunits/ha% TotalPerfarmLand use Area, haNumber Farm types(Plantedirektoratet 2003)DARCOFOutline1. Problems in European aquatic environment2. Development in organic farming3. Effect of conversion to organic mixed/dairy farming4. Effect of conversion to organic arable farming5. ConclusionCharacteristics of Danish dairy farms4459 4764 Animal feed consumption, FU/DE4400 5700 Average yield, FE/ha6855 7373 Milk production per cow, Kg milk/cow41 51 Cereal yield, hkg/ha, 1,28 1,46 Stocking rate, DE/ha100 68 Agricultural area, ha128 99 Livestock units (DE)81,9 61,3 Number of cows per farmOrganic ConventionalAverageFØI-statistik, 1999Kristensen et al., 2003N surplus on dairy farms (kg N ha-1 year-1)FØI-statistik, 1999Kristensen et al., 2003-100-50050100150200250Farm typekg N per haRainfallImported fodderMineral fertilizerOrganic fertilizerN2 fixationExported cropsMilkMeatOrganicConventionalInput: 238 Output: - 39 Output: - 57N surplus: 105 Input: 144 N surplus: 181 INPUTOUTPUTN surplus and N loss on dairy farms (kg N ha-1 year-1)181105-119-54-36-26-25-26-119-54-26-26-36-25105181-200-150-100-50050100150200Farm typekg N per haN surplusAmmoniavolatilationDenitrificationN leachingOrganicConventionalFØI-statistik, 1999Kristensen et al., 2003N surplus on dairy farms(Kg N ha-1 year-1)FØI-statistik, 1999Kristensen et al., 2003Note: The numbers below the symbols shows the stocking rate (animal units per ha) of the study. 0501001502002501988 1993 1998 2003YearsN surplus (kg N per ha) OrganicConventional 1.761.7 1.461.24  1.241.301.461.30Nitrate leaching from grassland (Foulum) ofdifferent age, composition and managementGrass-clover Ryegrasskg NO3-N ha-1yr-10255075100125kg NO3-N ha-1yr-102550751001250177017712881288Production yearProduction year2000-20012001-2002GrazedCutP surplus of dairy farms(Kg P ha-1 year-1)Studielandbrugene, 1997-2001Halberg et al., 2003http://www.vmp3.dk/Files/Filer/Rap_fra_t_grupper/VMP_III_Final_med_bilag.pdf-200204060801000123456Dyretæthed, DE/haP-overskud bedrift, kg P/haKonv. planteavl u. dyrKonv. planteavl m. sl.svinKonv. svin indeKonv. svin frilandKonv. kvægØko. kvægØko. svin frilandP surplus on dairy farms(Kg P ha-1 year-1)Studielandbrugene, 1997-2001Halberg et al., 2003http://www.vmp3.dk/Files/Filer/Rap_fra_t_grupper/VMP_III_Final_med_bilag.pdf-15-10-5051015202530Farm typekg P per haImported fodderMineral fertilizerOrganic fertilizerExported cropsMilkMeatOrganicConventionalInput: 34 Output: 8 Output: - 17P surplus: 8Input: 16 P surplus: 17 OUTPUTINPUTDARCOFOutline1. Problems in European aquatic environment2. Development in organic farming3. Effect of conversion to organic mixed/dairy farming4. Effect of conversion to organic arable farming5. ConclusionNutrient dynamicsCrop rotation experimentRotation 1  Rotation 2  Sædskifte 4 S. barley:ley Grass-clover S. wheat* Lupin* S. barley:ley Grass-clover W. wheat* Peas/barley* S. oats* W. wheat* W. cereals* Peas/barley* *: Cover crops are used Experimental treatments:• Crop rotation (proportion of cereals)• +/- cover crop• +/- animal manure (40% af norm)1997 1998 1999 2000 2001kg/ha (85% DM)02000400060008000JyndevadFoulumFlakkebjergWinter wheat ÷ manureGrain yield in rotation 2Foulum05101520253035Flakkebjerg Jyndevadppm102030NO3-NK97 98 99 00 97 98 99 00 97 98 99 00Concentrations of nitrate-N and K in soil waterJyndevad Foulum Flakkebjerg HolebyNitrate-N (kg N/ha)020406080100Without cover cropWith cover cropbaaabaN leaching in rotation 2Model simulation of N balance on Danish arable farms • Organic scenarios:• Basic: Crop rotation dominated by spring cereals with catch crops in 40% of crops and 20% clover/grass.• + catch crops:  Catch crops (white clover/rye grass) in 70% of the crops.• 0 fertilisation: No manure is used.• Conventional scenarios:• Basic: Crop rotation dominated by winter cereals and catch crops in 6% of the crops.• + catch crops: Catch crops (ryegrass) in 36% of the crops.Note: Scenarios are representative for Danish agriculture.Model simulation of N balance on Danish arable farms • N balance at field level (incl. N leaching and changes in soil Norganic matter) - calculated for scenarios using the FASSET model at:• Three soil types (Sandy soil, loamy sand and sandy loam)• Two levels of soil organic matter (high and low).N surplus on arable farms (kg N ha-1 year-1)Berntsen et al., 2004-150-100-50050100150200Farm typekg N per haMineral fertilizerOrganic fertilizerN2 fixationOther inputsGrain yieldStraw and coarsefodderConventional OrganicBasic+ catch    crops Basicno fertili-sation+ catch   cropsN surplus: 61  N surplus: 38  N surplus: 40  N surplus: 31  N surplus: 60 Input: 103Input: 151  Input: 147  Input: 150  Input: 150 Output: - 110 Output: - 72 Output: - 86  Output: - 91 Output: - 112 INPUTOUTPUTN surplus and N loss on arable farms (kg N ha-1 year-1)Berntsen et al., 200411 19-9 -8 -4-36-27-32 -36-29-11-11-8 -10-1031 40 38-3-3-2-26160-80-60-40-20020406080100Farm typekg N per haN surplusAmmonia volatilationDenitrificationN leachingSoil N poolConventional OrganicBasic+ catch    crops Basicno fertili-sation+ catch    cropsN leaching on arable farms (kg N ha-1 year-1)OrganicBasis+ catch crop0 fertilisationConventionalBasis+ catch cropSandy loam (low)Loamy sand (low)Sand (low ) 0102030405060N leaching (kg N ha-1 year-1)Cropping systemsSoil type and level of organic matterSandy loam (low)Sandy loam (high)Loamy sand (low)Loamy sand (high)Sand (low)Sand (high)Berntsen et al., 2004Change in soil N pool on arable farms (kg N ha-1 year-1)OrganicBasis+ catch crop0 fertilisationConventionalBasis+ catch crop Sandy loam (low)Loamy sand (low)Sand (low)-30-20-10010203040Soil N pool (kg N ha-1 year-1)Cropping systemSoil type and level of organic matterSandy loam (low)Sandy loam (high)Loamy sand (low )Loamy sand (high)Sand (low)Sand (high)Berntsen et al., 2004DARCOFConclusion• Nitrate leaching from agriculture is a common problem for European aquatic environment• Conversion to organic mixed/dairy farming decrease leaching of N because of decreased stocking rate and level of N-fertilizer• Conversion to organic arable farming increase soil fertility, but has little effect on leaching of Nitrate at least at farm level and on a short term• Organic farming has positive environmental benefits on the soil and the ecosystem Assessment of environmental impact of organic farmingSource: Hansen et al. (2001)

Impact of Organic farming on aquatic environment

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