Presentation in Lednice 1 st July 2004 Impact of Organic farming on aquatic environment By Erik Steen Kristensen and Marie Trydeman Knudsen Danish Research Centre for Organic Farming (www.darcof.dk) DARCOF
DARCOF (Danish Research Centre for Organic Farming)
Presentation 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 year DARCOF
Outline 1. Problems in European aquatic environment 2. Development in organic farming 3. Effect of conversion to organic mixed/dairy farming 4. Effect of conversion to organic arable farming 5. Conclusion DARCOF
Nitrate concentration in European rivers Development since 1955 Extension 1994-96 Source: European Environment Agency (http://dataservice.eea.eu.int/atlas/viewdata/viewpub.asp?id=546)
Nitrate in groundwater European Environment Agency, 2003 Source: European Environment Agency (http://dataservice.eea.eu.int/atlas/viewdata/viewpub.asp?id=110)
Nitrate Vulnerable Zones Source: European Environment Agency (http://dataservice.eea.eu.int/atlas/viewdata/viewpub.asp?id=150)
Phosphorus concentration in European rivers og lakes Rivers (1994-96) Lakes and reservoirs Source: European Environment Agency (http://dataservice.eea.eu.int/atlas/viewdata/viewpub.asp?id=546 )
Status of European waters Indicators Nitrate in groundwater Nutrients in rivers Phosphorus in lakes Nutrients in marine waters Assessments No 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. Concentrations 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. Eutrophication of European lakes is decreasing. Still many lakes and reservoirs with high concentrations of phosphorus - highest in accession countries. Nutrient concentrations in Europe s seas have generally remained stable over recent years. European Environment Agency, 2003
Outline 1. Problems in European aquatic environment 2. Development in organic farming 3. Effect of conversion to organic mixed/dairy farming 4. Effect of conversion to organic arable farming 5. Conclusion DARCOF
Development of organic farming in EU-15 countries DARCOF http://www.organic.aber.ac.uk/stats.shtml
180000 160000 140000 120000 100000 80000 60000 40000 20000 0 8000 7000 6000 5000 4000 3000 2000 1000 0 1988 1990 1992 1994 1995 1996 1997 1998 1999 2000 Total hectares 2001 2002 Number of farms Development of organic farming in Denmark Hectares Farms
Organic farms in Denmark 2003 Area, ha Land use Farm types Num ber Per farm Total % Livestock units/ ha Cereals, maturity Silage (maize + pea/ barley) Clover/ grass Others Permanent grass Organic, total 3700 48 178.000 6,4 Mixed/dairy farms 770 115 50 1,28 15 28 42 0 13 Arable farms 530 83 25 0,07 Others (incl. pigs/poultry) 2400 19 25 0,65 59 10 15 11 5 (Plantedirektoratet 2003)
Outline 1. Problems in European aquatic environment 2. Development in organic farming 3. Effect of conversion to organic mixed/dairy farming 4. Effect of conversion to organic arable farming 5. Conclusion DARCOF
Characteristics of Danish dairy farms Average Conventional Organic Number of cows per farm 61,3 81,9 Livestock units (DE) 99 128 Agricultural area, ha 68 100 Stocking rate, DE/ha 1,46 1,28 Cereal yield, hkg/ha, 51 41 Average yield, FE/ha 5700 4400 Milk production per cow, Kg milk/cow 7373 6855 Animal feed consumption, FU/DE 4764 4459 FØI-statistik, 1999 Kristensen et al., 2003
N surplus on dairy farms (kg N ha -1 year -1 ) 250 Conventional 200 Input: 238 150 Organic kg N per ha 100 50 0 N surplus: 181 Input: 144 N surplus: 105 INPUT Rainfall Imported fodder Mineral fertilizer Organic fertilizer N2 fixation Exported crops -50 Output: - 57 Output: - 39 Milk Meat OUTPUT -100 Farm type FØI-statistik, 1999 Kristensen et al., 2003
N surplus and N loss on dairy farms (kg N ha -1 year -1 ) 200 Conventional 150 Organic 100 181 kg N per ha 50 0-50 -100-36 -26-119 -119 105-25 -26-54 105-54 -26-25 N surplus Ammonia volatilation Denitrification -150-26 -36 N leaching -200 Farm type FØI-statistik, 1999 Kristensen et al., 2003
N surplus on dairy farms (Kg N ha -1 year -1 ) N surplus (kg N per ha) 250 200 150 100 50 1.76 1.7 1.24 1.24 1.46 1.30 1.46 1.30 Organic Conventional 0 1988 1993 1998 2003 Years Note: The numbers below the symbols shows the stocking rate (animal units per ha) of the study. FØI-statistik, 1999 Kristensen et al., 2003
Nitrate leaching from grassland (Foulum) of different age, composition and management kg NO3-N ha -1 yr -1 kg NO3-N ha -1 yr -1 125 100 75 50 25 0 125 100 75 50 25 Grass-clover Ryegrass 0 1 7 7 0 1 7 7 Production year 2000-2001 2001-2002 0 1 2 8 8 1 2 8 8 Production year Grazed Cut
P surplus of dairy farms (Kg P ha -1 year -1 ) 100 P-overskud bedrift, kg P/ha 80 60 40 20 0-20 0 1 2 3 4 5 6 Dyretæthed, DE/ha Konv. planteavl u. dyr Konv. planteavl m. sl.svin Konv. svin inde Konv. svin friland Konv. kvæg Øko. kvæg Øko. svin friland Studielandbrugene, 1997-2001 Halberg et al., 2003 http://www.vmp3.dk/files/filer/rap_fra_t_grupper/vmp_iii_final_med_bilag.pdf
P surplus on dairy farms (Kg P ha -1 year -1 ) 30 Conventional 25 Input: 34 kg P per ha 20 15 10 5 0-5 -10 P surplus: 17 Output: - 17 Organic Input: 16 P surplus: 8 Output: 8 INPUT Imported fodder Mineral fertilizer Organic fertilizer Exported crops Milk Meat -15 Farm type OUTPUT Studielandbrugene, 1997-2001 Halberg et al., 2003 http://www.vmp3.dk/files/filer/rap_fra_t_grupper/vmp_iii_final_med_bilag.pdf
Outline 1. Problems in European aquatic environment 2. Development in organic farming 3. Effect of conversion to organic mixed/dairy farming 4. Effect of conversion to organic arable farming 5. Conclusion DARCOF
Nutrient dynamics
Crop rotation experiment Rotation 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)
Grain yield in rotation 2 Winter wheat manure kg/ha (85% DM) 8000 6000 4000 2000 Jyndevad Foulum Flakkebjerg 0 1997 1998 1999 2000 2001
Concentrations of nitrate-n and K in soil water 30 Jyndevad 35 30 Foulum Flakkebjerg 25 ppm 20 20 15 10 10 5 0 97 98 99 00 97 98 99 00 97 98 99 00 NO3-N K
N leaching in rotation 2 100 80 a Without cover crop With cover crop Nitrate-N (kg N/ha) 60 40 b a b a a 20 0 Jyndevad Foulum Flakkebjerg Holeby
Model 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 N organic 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 ) 200 Organic Conventional kg N per ha 150 100 50 0 Input: 147 Input: 151 Input: 150 Input: 150 Input: 103 N surplus: 61 N surplus: 60 N surplus: 31 N surplus: 40 N surplus: 38 INPUT Mineral fertilizer Organic fertilizer N2 fixation Other inputs Grain yield -50-100 -150 Output: - 86 Basic Output: - 91 + catch crops Output: - 72 no fertilisation Farm type Output: - 110 Basic Output: - 112 + catch crops Straw and coarse fodder OUTPUT Berntsen et al., 2004
N surplus and N loss on arable farms (kg N ha -1 year -1 ) 100 80 Organic Conventional kg N per ha 60 40 20 0-20 -40-60 -80 61 11-36 -11-3 Basic 60 19-27 -11-3 + catch crops 31-9 -8-4 -32-36 -8 no fertilisation Farm type 40 38-10 -2 Basic -29-10 -2 + catch crops N surplus Ammonia volatilation Denitrification N leaching Soil N pool Berntsen et al., 2004
N leaching on arable farms (kg N ha -1 year -1 ) 60 50 40 30 20 10 N leaching (kg N ha-1 year-1) Sandy loam (low) Sandy loam (high) Loamy sand (low) Loamy sand (high) Sand (low) Sand (high) Sand (low ) 0 Soil type and level of organic matter Loamy sand (low ) Sandy loam (low ) Organic Basis + catch crop 0 fertilisation Conventional Basis + catch crop Cropping systems Berntsen et al., 2004
Change in soil N pool on arable farms (kg N ha -1 year -1 ) 40 30 Soil type and level of organic matter 20 10 0-10 -20 Soil N pool (kg N ha-1 year-1) Sandy loam (low ) Sandy loam (high) Loamy sand (low ) Loamy sand (high) Sand (low ) Sand (high) Sand (low ) Loamy sand (low ) Sandy loam (low ) Organic Basis + catch crop 0 fertilisation Conventional Basis + catch crop -30 Berntsen et al., 2004 Cropping system
Conclusion 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 DARCOF
Assessment of environmental impact of organic farming Source: Hansen et al. (2001)