Dan

mar

ks J

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rugs

For

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inis

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Fø

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Danish efforts to reduce P loss from agriculture to the aquatic

environmentGitte Rubæk

Danish Institute of Agricultural Sciences

DJF

The P surplus in Danish AgricultureP

im

po

rt (

1000

to

nn

es)

(Kyllingsbæk, 2005)

P s

urp

lus

(Kg

P h

a-1)

Imported animal feed

Waste products

Mineral fertilizers

DJF

-5

0

5

10

15

20

25

30

35

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

kg f

osfo

r pe

r ha

P o

vers

kud

(kg

P /

ha

)The P surplus in danish agriculture

1,4 tonnes P ha-1 has accumulated in on agricultural

landTotal P (mg P/kg jord)

De

pth

(cm

)

Agricult.

Forest

DJF

Geographic distribution of the P surplus

(Dalgård et al., 2004)

P surplus in 2001(kg ha-1 agricultural land)

DJF

Very high spatial variability in P losses from land

Source

område medhøjt indhold af

flytbartfosfor

Areas with a high content of potentially mobile P

Transport

med højttransport-potentiale

områdeAreas with a high potential for P transport

Critical source area

DJF

P losses in landscape

Stream

Cultivated land(source area)

Soil erosion

Surface run-off

Meadows, occasionally flooded(P deposition)

Leaching and potential lossthrough drainage system

Stream Banks(source)

Buffer Zone(P deposition)

2 m uncultivated zone(Law enforced)

Drained low-land soil (Source area)

DJF

P discharge to coastal waters in DK

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

spildevand +spredt bebyggelse

industri

dambrug

gårdbidrag

dyrket areal

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 20001900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

spildevand +spredt bebyggelse

industri

dambrug

gårdbidrag

dyrket areal

(after Rüegg og Østergaard, 2002)

Waste water

Industry

Fish hatchery

Farm contribution

Diffuse losses, cropped land

DJF

P loss from farmland to surface watersin DK - estimatesCertainty of estimate: (+) = Incufficient; (+++) = average; (+++++) = high

Total P (tonnes year-1)Erosion-related losses 287 - 695• Water erosion (++) 7 - 35• Stream bank erosion (++) 275 - 645• Wind erosion (+) 5 – 15

Drainage related leaching, total 65 - 405• Leaching from high risk areas (mineral soils) (+) 15 - 90• Leaching from other areas (mineral) (+++) 20 - 90• Leaching from lowland organic soils (+) 30 – 225

Groundwater related leaching, total 125 - 210• Leaching to shallow ground water (++) 80• Leaching to deeper ground water(++) 45 – 130

Atmospheric deposition (++++) < 5

SUM (without leaching to deep ground water) 440 - 1180

Kronvang & Rubæk, 2005

DJF

“Experts” conclusions during the preparations for VMPIII

A dual strategy combining:

• General measures to reduce the P surplus and optimizing P distribution on farmland– Improved feeding (Digestibility, phytase

additions, reduced safety margins based on improved knowledge of physiological need)

• Targeted measures to reduce P losses from high-risk areas (critical source areas)

Poulsen and Rubæk, 2005, DIAS report nr 68

DJF

The Danish Action Plans (Vand-Miljø-Planer)

• VMP-I and VMP-II had focus on:– N emissions from agriculture– P emissions from point sources

• The VMPIII addresses:– The P surplus in agriculture– The P losses from farmland– …and N leaching, vulnerable nature,

organic farming and a “slurry action plan”

DJF

The political agreement on P in VMPIII

• 50% reduction in the annual P surplus– tax on feed-phosphates– improved utilization of animal feed P

• Buffer zones along streams and lakes– volunteer subsidized agreements (MVJ)– 10 meter zones, 50.000 ha

• Research and development…..

DJF

P related research and development in VMPIII

• Reducing the P surplus – P utilization in animal husbandry – Slurry treatment - including combustion

• “Land management”– A Danish P index– Management of Stream Banks, Buffer zones, Flood

plains and low land – Management on farmland– Modeling P effects in estuaries– Cost and benefits of mitigation strategies– A web-based interactive tool for N and P

management of watersheds

DJF

Land management research projects

Mapping layers, mapping

techniques

Modeling P effects in estuaries

Management of buffer zones, stream banks, floodplains and

lowlands

Costs and Benefits of

mitigation strategies

Interactive web-based

tool for nutrient management

A Danish P index

Management on farmland

DJF

Silkeborg, 3-7 sep 2007