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Nitrate leaching and pesticide use in energy crops

Uffe Jørgensen, Danish Institute of Agricultural Sciences,

Dep. of Agroecology, Research Centre Foulum

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Biomass use and production in Denmark

• Total energy use 2004 839 PJ• Biomass (straw, wood, biogas) 59 PJ• Municipal waste 37 PJ• Wind power 24 PJ

Renewable energy 14% of total energy use

Energy crops:• 10-20,000 ha. rape & c. 1000 ha. willow

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Danish agriculture can produce much more energy – but also have to fulfil …

• The Water Framework Directive• The Ground Water Directive• The Habitat Directive• The 3rd national action plan on the

aquatic environment• The national action plan on pesticides• Etc.

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Annual versus perennial crops

• Perennial crops have the most efficient nutrient use

• Perennial crops are hardy and competitive (not during establishment)

• Therefore, perennial crops are more easy to produce with low environmental impacts

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Nitrate leaching from energy crops

•Measured by installation of suction cups below the root zone

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Nitrate leaching from willow Coarse sand

0

10

20

30

40

50

60

70

80

90

100

jul

93

jan

94

jul

94

jan

95

jul

95

jan

96

jul

96

jan

97

jul

97

jan

98

jul

98

jan

99

jul

99

jan

00

mg

nit

rate

-N/li

tre

0 N

75 N

sludge with c. 140 N

sludge with c. 280 N

drinking water quality

150 kg N

105 kg N

3-9 kg N

13-42 kg N

1-16 kg N

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Nitrate leaching from miscanthus loamy sand

0

20

40

60

jul 9

3

jan

94

jul 9

4

jan

95

jul 9

5

jan

96

jul 9

6

jan

97

jul 9

7

jan

98

jul 9

8

jan

99

jul 9

9

jan

00

mg

NO

3-N

/lit

re s

oil

wa

ter 0 N

75 N

140 N slurry

280 N slurry

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Leaching from common agricultural crops on sand

Peas Winterbarley

Winterwheat

Oats Winterbarley

Winterrape

Winterwheat

100

80

60

40

20

0

20

40

60

80

100

120

140

160

180

200

220

100

80

60

40

20

0

20

40

60

80

100

120

140

160

180

200

220

N leaching, kg per haConcentration of nitrate-N

Apr88 Oct88 Apr89 Oct89 Apr90 Oct90 Apr91 Oct91 Apr92 Oct92 Apr93 Oct93 Apr94

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25

50

75

100

125

150

175

200

01-09-2001

01-12-2001

01-03-2002

01-06-2002

01-09-2002

01-12-2002

01-03-2003

01-06-2003

01-09-2003

01-12-2003

01-03-2004

01-06-2004

01-09-2004

01-12-2004

01-03-2005

01-06-2005

01-09-2005

01-12-2005

mg

nit

rate

/litr

e

crop rotation

miscanthus

mis. environmentally optimised

potatoes / ryegrass / spring barley + ryegrass /potatoes / oats+ryegrass /potatoes/persian clover+fodder radish/ white cabbage 118 kg N/ha 109 kg N/ha 69 kg N/ha 35 kg N/ha 168 kg N/ha

Protection of drinking water on the renewable energy island, Samsø

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How much can nitrate leaching be reduced by changing to energy crop

production?

Energy crops substitute Reduced leaching c.

Crop rotation: 50 kg N/ha.Annual set aside: 30 kg N/ha.Grass fallow: -10 kg N/ha.

• Mean N-abatement cost in the latest national action plan for the aquatic environment: 21 DKK per kg N

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Pesticide use in energy crops

• Quality demands not so crucial for

energy use

• Hardy and competitive crops

• Weed management is important

during establishment of

perennial crops

• Pesticide-free production possible

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Mechanical weed management

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Annual pesticide treatments in energy crops

• Triticale 1997-98 0,9 (0,3 - 1,7)• Triticale 1998-99 0,7 (0 - 0,9)

• Miscanthus Foulum, 1993-2000 0,6 (0 - 3,0)• Miscanthus Jyndevad, 1993-2000 1,0 (0 - 5,9)

• Willow Foulum, 1993-2000 0• Willow Jyndevad, 1993-2000 0,4 (0 - 3,0)

• Mean in Danish agriculture 2,2• Reduction target 2009 1,7

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Energy crops can ensure water qualityBut what about quantity?

Willow uses a lot of water!

Soil water percolation from

winter wheat willow

1993-94 522 mm 404 mm

1994-95 648 mm 537 mm

1995-96 77 mm 0 mm

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Miscanthus saves water

Soil water content in willow and miscanthus

10

15

20

25

30

35

01-mar 01-apr 01-maj 01-jun 01-jul 01-aug 01-sep 01-okt 01-nov 01-dec 01-jan

% v

an

d (

0 -

50

cm

)

Elefantgræs (miscanthus)

Pil (willow)

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Conclusions

• Energy crops and good water quality can be co-produced

• Perennial energy crops reduce nitrate leaching– by up to 50 kg N/ha

– especially efficient in utilising manure and sludge

• Compared with fallow and afforestation energy crop production secures continued animal production

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Willow, poplar & alder

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Miscanthus

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Reed Canary grass