Nitrate leaching and pesticide use in energy crops

1. Nitrate leaching and pesticide use in energy crops Uffe Jørgensen, Danish Institute of Agricultural Sciences, Dep. of Agroecology, Research Centre Foulum

2. 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

3. 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.

4. 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

5. Nitrate leaching from energy crops • Measured by installation of suction cups below • the root zone

6. Nitrate leaching from willow Coarse sand 150 kg N 105 kg N 13-42 kg N 1-16 kg N 3-9 kg N

7. Nitrate leaching from miscanthusloamy sand

8. Leaching from common agricultural crops on sand 100 100 80 80 60 60 40 40 20 20 0 0 Peas Winter Winter Winter Winter Winter Oats 20 20 barley wheat barley rape wheat 40 40 60 60 80 80 100 100 120 120 140 140 160 160 180 180 N leaching, kg per ha 200 200 Concentration of nitrate-N 220 220 Apr88 Oct88 Apr89 Oct89 Apr90 Oct90 Apr91 Oct91 Apr92 Oct92 Apr93 Oct93 Apr94

9. Protection of drinking water on the renewable energy island, Samsø

10. How much can nitrate leaching be reduced by changing to energy crop production? Energy crops substituteReduced 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

11. 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

12. Mechanical weed management

13. 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

14. 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

15. Miscanthus saves waterSoil water content in willow and miscanthus

16. 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

17. Willow, poplar & alder

18. Miscanthus

19. Reed Canary grass