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Benefits and risks of applying compost to European soils Luca Montanarella.

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Presentation on theme: "Benefits and risks of applying compost to European soils Luca Montanarella."— Presentation transcript:

1 Benefits and risks of applying compost to European soils Luca Montanarella

2 Spatial data layer of estimated OC contents in the surface horizon of soils in Europe (30cm), 1km grid size. Status of Soil Organic Carbon in European soils:

3 Hypothetical carbon stock build-up by LULUCF measures Actual terrestrial carbon stock Max. potential carbon stock achievable through LULUCF measures Max. potential carbon stock at climax Terrestrial organic carbon pool Terrestrial carbon stock depletion by historical human induced LULUCF activities Ca. 60,000 B.C. to A.D Last green revolutionpresentfuture time Soil Organic Carbon dynamics

4 Monitoring SOM on Broadbalk, Rothamsted %OC FYM FYM since 1885 FYM since 1968 NPK No fertilisers or manures FYM applied at 35 t ha -1 yr -1 Goulding

5 Soil specific carbon sequestration potential Max tC Min tC Actual tC Max & Min tC are soil specific Years tC Potential Carbon Sequestration, PCS Carbon Sequestration Rate, CSR Potential Carbon loss, PCL (Risk assessment) Carbon Loss Rate, CLR

6 SOC content is depending on humidity, temperature, soil type and land use [after Loveland, NSRI, Cranfield University, Silsoe] Example: Change in organic carbon content of topsoils in England and Wales

7 Carbon losses from all soils across England and Wales (Bellamy et al., Nature Sep 2005, based on ca samples, 0-15cm) Bellamy et al. estimate annual losses of 13 million tonnes of carbon. This is equivalent to 8% of the UK emissions of carbon dioxide in 1990, and is as much as the entire UK reduction in CO2 emissions achieved between 1990 and 2002 (12.7 million tonnes of carbon per year).

8 CountryMunicipal solid waste production Biowaste actually collected Greenwaste actually collected Biowaste potentially collectable Greenwaste potentially collectable Austria (*) Belgium- Flanders (***) Belgium- Wallonia Germany Denmark France Finland Spain (**) 60/6 600 Greece4 200//1 800 Italy (****) 1 100/9 000 Ireland1 848//440 Luxembourg Netherlands Portugal3 600/ Sweden United Kingdom European Union (*) Biowaste of industrial origin; (**) Catalonia; (***) Belgium total; (****) Italy: CIC and Italian Environmental Agency data for J. Barth, An estimation of European compost production, sources, quantities and use, EU Compost Workshop Steps towards a European Compost Directive, Vienna, 2-3 November Modified for France by I. Feix. Data from Germany are from the report Bundesgütegemeinschaft Kompost: Verzeichnis der Kompostierungs- und Vergärungsanlagen in Deutschland, Total biowaste and green waste arising in the European Union (1,000 t/y)

9 Soil organic matter Origin Turnover Complexity Decomposing fresh OM (Particulate organic matter) Microorganisms Colloidal OM Polysaccharides and biomolecules Humic substances soluble OM -OH CO 2 C org


11 Potential measures for cropland Freibauer et al. 2003

12 MeasurePotential soil C sequestration rate (t CO 2.ha -1.y -1 ) Estimated uncertainty (%) Ref. / notes Limiting factorSoil sequestration potential (10 6 CO 2.y -1 ) given limitation Ref. / notes Animal manure 1.38> 50%1Manure available = t dm.y Crop residues2.54> 50%1Surplus straw = t dm.y Sewage sludge0.95> 50%1, 2Sewage sludge available in the mid-time (2005) = t dm.y Composting1.38 or higher>> 50%3, 2Potential production of composted materials present in MSW = 13 to t dm.y -1. Figures include processing of biowaste from agro- industrial by-products, but neither manure, nor crop residues Smith et al. (2000); per hectare values calculated using the average C content of arable top soils (to 30 cm) of 53 t C.ha -1 ; Vleeshouwers and Verhageb (2002), cf. table The sequestration values are based on a load rate of 1 t ha -1.y -1, which was the lowest safe limit in place (in Sweden) at the time of analysis for this figure (1997). A higher loading rate would give a higher sequestration rate per area. As the limiting factor for the application of compost is the amount of producible compost, a higher loading rate on a certain area would imply that a more limited area could be treated. -3. Assumed to be the same as animal manure figure of Smith et al. (2000). -4. Total figure for EU15 calculated from figures in Smith et al. (2000). Total amount of manure available from Smith et al. (1997). -5. Total figure for EU15 calculated from figures in Smith et al. (2000). Total amount of surplus cereal straw available from Smith et al. (1997).

13 Total carbon sequestration potential of measures for increasing soil carbon stocks in agricultural soils for Europe (EU15) and limiting factors. European Climate Change Programme ECCP

14 Land surface (%UAA) Mean level of Cu ( -1 dm) Cu rates (kg.ha -1.y -1 ) Cu annual loads (t.y -1 ) over France Urban sewage sludge1 to 4% MSW compost0.1% Biodegradable wastes Greenwaste compost0.2% Households biowaste compost 0.02% Animal effluents20-25%Ex.: 52 cattle; 730 pigs 0.7 cattle; 2.3 pigs (all an. effl.) Agricultural practices P fertilisers80-90%/ Cu fungicides~3% (vineyards & arboriculture) /0.8 to to Atmospheric depositions 100%/0.006 to to 462 Comparative rates and loads of Cu inputs into French soils TWG Organic Matter



17 Conclusions Soil Organic carbon levels in Europe are low and are constantly declining. There is the urgent need to reverse this negative trend Compost and bio-waste could provide a valuable source of organic matter for European soils. Long-term fate of the exogenous organic material in soils needs to be taken into account, depending on the pedo-climatic local conditions. Potential contamination of bulk organic materials, like compost, sludges and other bio-wastes is a potential threat to human health Careful application of QA/QC and of the precautionary principle is a pre-requisite for increased acceptance of these materials as soil improvers.

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