European Summer School on Soil Survey

Transcription

1 European Summer School on Soil Survey Decline in Soil Organic Matter Contents Robert J A Jones & Luca Montanarella European Soil Bureau Institute of Environment & Sustainability Second European Summer School on Soil Survey Joint Research Centre Ispra (VA) Italy July 2004 Thematic Strategy for Soil Protection: Threats to Soil

2 The impact of human activities on soil Diffuse input of contaminants as particulates Persistent substances Acids Pesticides & herbicides Manures and fertilisers Heavy metals Sewage sludge Gravel extraction Sealing Blocking of soil functions important to the ecology of the landscape Destruction of soil Gradual disappearance of farms Gradual destruction of soils Reduction in soil fertility Soil erosion Decline in Organic Matter Changes in the structure of soils Reduction in soil fertility Accumulation/ contamination Compaction salinisation Acidification Contamination of soils and ground water with applied agrochemicals and atmospheric pollutants Changes in soil composition Adverse impacts on living organisms in the soil Release of toxic substances Destruction of soil European Soil Protection Strategy

3 Stocktaking on the threats to soil Priority Threats: 1. Erosion 2. Organic matter decline 3. Contamination Five additional threats: Compaction Salinisation Sealing Floods & Landslides Biodiversity Stocktaking means making an inventory = collecting data Bruxelles, COM(2002) 179 final COMMUNICATION FROM THE COMMISSION TO THE COUNCIL, THE EUROPEAN PARLIAMENT, THE ECONOMIC AND SOCIAL COMMITTEE AND THE COMMITTEE OF THE REGIONS Towards a Thematic Strategy for Soil Protection agriculture/soil_protection.htm CIRCA website Basic principles: Polluter pays & adopt preventative action Precautionary principle Rectification at source Subsidiarity & proportionality Thematic Strategy for Soil Protection in Europe

4 Importance of Soil Organic Matter Organic material in the soil is essentially derived from residual plant and animal material, synthesised by microbes and decomposed under influence of temperature, moisture and ambient soil conditions Soil organic matter is extremely important in all soil processes Cultivation can have a significant effect on the organic matter content of the soil In essentially warm and dry areas like Southern Europe, depletion of organic matter can be rapid because the processes of decomposition are accelerated at high temperatures Generally, plant roots are not sufficiently numerous to replace the organic matter that is lost.

5 Benefits of Soil Organic Matter Storehouse for nutrients Source of fertility Contributes to soil aeration thereby reducing soil compaction Important building block for the soil structure Aids formation of stable aggregates Improves infiltration/permability Increase in storage capacity for water. Buffer against rapid changes in soil reaction (ph) Acts as an energy source for soil micro-organisms

6 Degradation: Loss of Soil Organic Matter During field operations, fresh topsoil becomes exposed and dries rapidly on the surface Organic compounds are released to the atmosphere result from breakdown of soil aggregates bound together by humic materials Unless the organic matter is quickly replenished, the system is in a state of degradation leading eventually to un-sustainability The removal of crop residues in dry ecosystems, which are inherently marginal, can cause such systems to be quickly transformed from a stage of fragility to total exhaustion and depletion

7 Factors influencing organic matter status of soils Natural factors: Climate Soil parent material: acid or alkaline (or even saline) Land cover and or vegetation type Topography slope and aspect Human-induced factors: Land use and farming systems Land management (cultivation) Land degradation

8 Factors affecting soil organic matter: Climate Temperature: OM decomposition rapid in warm climates decomposition is slower for cool regions Result: Within zones of uniform moisture and comparable vegetation -- Av total OM increases 2x to 3x for each 10 deg C fall in mean temperature Moisture: OM decomposition rapid in warm climates decomposition is slower for cool regions Result: Under comparable conditions Av total OM increases as the effective moisture increases

9 Factors affecting soil organic matter: Soil Properties - Texture Texture Topsoil OM (%) Subsoil OM (%) Sands Clay loams Clays

10 Core data European data set according to CORINE land cover classification Extended data CORINE supplemented with adapted USGS Eurasia land cover Roland Hiederer, Land Management Unit

11 Micheli Declining soil organic matter %OC Management/vegetation % C Old pasture (8-18cm) 1.5 Old woodland (13-18cm) 2.4 Broadbalk, after 50 years continuous wheat, 1893 No manure since 1839 (0-23cm) 0.9 Complete minerals and 185kg 1.1 (NH 4 ) 2 SO 4 most years since tons of farmyard manure 2.2 annually since 1843 (0-23cm) FYM since 1885 Monitoring SOM at Rothamsted NPK FYM FYM since No fertilisers or manures 0 Micheli FYM applied at 35 t ha -1 yr Goulding 1990

12 Factors affecting soil organic matter: Cultivation Expts in USA show: Lower OM contents found in cultivated compared to their undisturbed or virgin equivalents Not possible to maintain OM of cultivated soils at virgin levels nor is it necessary to do so Decline of in OM of 30-40% has serious effect on soil structure & fertility Expts in France show: Carbon stocks are lower under normal tillage than under reduced or no-till systems Stock C (t/ha) Mesures Labour Semis direct Travail superficiel Extrapolation Années Arrouays

13 4 Factors affecting soil organic matter: Crop rotation %OC in soil course rotation 3-course rotation permanent fallow After Goulding, Rothamsted

14 Soil Data available in Europe National Soil Survey data: 1:10,000; 1:25,000; 1:50,000 1:250,000 scale European Soil data: 1:250,000 scale 1:1,000,000 scale European Soil Database Spatial and point data Status of soil data for the whole of Europe: harmonised according to a standard international system of soil classification agreed procedures for data distribution now in place improved resolution planned for the future activities at continental level coordinated by ESB Network Soil Information for Europe

15 Availability of Soil Surveys in Europe, :250,000 scale 1:50,000 scale Soil Information at National level in Europe

16 European Soil Database: WRB classification

17 EuroRussia Soil Database (WRB)

18 Declining soil organic matter in S Europe Knowledge-based approach 74% of the land in southern Europe has a surface soil horizon (0-30cm) that on average contains less than 2% OC (3.4% OM)

19 METHODOLOGY: Pedo-Transfer Rules (PTRs) were applied to the European Soil Database Characteristics of PTRs: PTRs of the European Soil Database are defined as structured if-then conditions, using a number of related environmental parameters The PTRs for organic carbon were transferred to spatial processing procedures and applied directly on spatial data layers in a GIS Detailed thematic information was provided by additional data from external sources (land cover, meteo/climate data) Final OC estimates verified by comparing modelled data with measured values from several thousand points in UK (England & Wales) and Italy Estimating Topsoil Organic Carbon

20 Organic Carbon Content (30cm) Organic Carbon (%) No Data > 35 Data sources Soil type Land cover Temperature Soil type Rasterization Spatial layers derived by rasterization of a Triangulated Irregular Network (TIN) model with weighted distance interpolation Temperature

21 Organic Carbon (%) No Data > 35 2 Organic Carbon Content (0-30cm) TEMPERATURE CORRECTION FOR OC Ceofficient for temperature variation (> 3 ground measurements) Correction Factor Temperature Range (AAAT deg. C) Semi-natural Cultivated Avg. Ground Data Model n ( t ) c TEMPcor = f * cos AAAT + ver October 2003 S.P.I Within belts of uniform moisture conditions and comparable vegetation, the average total content of organic matter in soils increases by 2x to 3x for each 10 deg C fall in mean temperature. Jones, Hiederer Rusco & Montanarella (2003)

22 Stocktaking of Soil Organic Carbon - 1 United Kingdom: Samples taken during National Soil Inventory (NSI) on a systematic 5km x 5km grid OC measurements from 5600 NSI points under all land uses Modelled Organic Carbon Content (%) TOPSOIL ORGANIC CARBON CONTENT Measured vs. Modelled Data (UK) Regression for NUTS Level 2: OC_GRD=0.89*OC_MODGRD+1.07 Aggregation at ground survey points Regression for catchments: OC_GRD=0.88*OC_MODGRD+1.11 Aggregation at ground survey points Measured Organic Carbon Content (%) Catchment avg. at ground sample Catchment avg. from spatial layer Coeff. Determination = 95%

23 Average Organic Carbon Content (%) Topsoil Organic Carbon: England & Wales TOPSOIL ORGANIC CARBON CONTENT Measured vs. Modelled, England & Wales all land cover classes Total ground sample points: Measured vs. Calculated All land cover (5591pts) 313 Bc Be Bgc Gds Gm Jeg Bd Bec Bgg Ges Gmf Lc Bds Bef E Gh Jcg Lg Soil Code Ground Data Lgs 107 Lo Od 33 Oe Model Data Pg Pgs Po 115 Pp Q Qc U Ql Rc Average Organic Carbon Content (%) TOPSOIL ORGANIC CARBON CONTENT Measured vs. Modelled, England & Wales Arable Land Total ground sample points: 1856 Arable (1856pts) Bc Be Bgc Gds Gm Jeg Lgs Oe Po Ql Bd Bec Bgg Ges Gmf Lc Lo Pg Pp Rc Bds Bef E Gh Jcg Lg Od Pgs Qc Soil Code Average Organic Carbon Content (%) Ground Data Model Data TOPSOIL ORGANIC CARBON CONTENT Measured vs. Modelled, England & Wales under Forest Total ground sample points: 369 Forest (349pts) Bc Be Bgg Ges Gmf Lc Od Po Ql Bd Bec E Gh Jcg Lgs Pg Pp U Bds Bgc Gds Gm Jeg Lo Pgs Qc Soil Code Ground Data Model Data

24 Decline in Organic Carbon content in Eng & Wales UK, After NSRI, Loveland et al. 2002

25 Stocktaking of Soil Organic Carbon - 2 Organic Carbon (%) No Data > 35 Italy: Non systematic sampling scheme Samples mainly from agricultural areas Clustered sampling in some areas 6586 sampling points Region Points OC % OC % Region Points OC % OC % (NUTS2) No. ground estimate (NUTS2) No. ground estimate Piemonte Marche Valle D'aosta Lazio Liguria Abruzzo Lombardia Molise Trentino-Alto Adige Campania Veneto Puglia Friuli-Venezia Giulia Basilicata Emilia-Romagna Calabria Toscana Sicilia Umbria Sardegna Total /Avg

26 Average Organic Carbon Content (%) Bc Bd TOPSOIL ORGANIC CARBON CONTENT Total ground sample points: Be Bea Bec Bef Measured vs vs. Calculated, Modelled, Italy Arable Land Bk Bv Bvc 49 E 5 Id Jeg Soil Code Lc Lg Lgp Lk 308 Lo 11 Avg. inside SMU: 8.0% Od Rc Re 30 Th 246 Vc Ground Data Model Data

27 Soil Organic Carbon stocks (0-30cm) in Gt (Pg) Organic Carbon tera t 0.0 Gt Organic Carbon (%) No Data > Finland (Yli Halla) : Calculated OC stock of 9-11Giga t Suggests that the European Soil Database may be overestimating OC in Finland (incl. Lakes?) Further point checks will be made in future

28 Stocks of C in soils (0-0.3 m) in France - Arrouays et al. (2002) 3,1 Pg Organic Carbon (%) No Data > 35 5,0 Pg OC content in topsoils (0-0.3 m) in France - European Soil Database

29 Scotland: Validation of estimates of topsoil OC against National Soil Inventory at 10km x 10km by MLURI Switzerland [Leifeld et al. 2003] Organic Carbon (%) No Data > 35 Belgium: estimates of topsoil OC stocks [Wesemael et al. 2003] Arable land Forest land - Ardennes

30 N. Italy: Emilia-Romagna [Ungaro et al. 2003] Czech Rep. [Kubat 2003]

31 Soil Organic Carbon and Erosion: Italy Organic Carbon (%) No Data > 35

32 Soil Organic Carbon and Erosion: Spain Organic Carbon (%) No Data > 35

33 Framework (DPSIR): Soil Organic Matter Decline European soil protection policy Agriculture intensification Climate Change Temperature rise Rainfall variation Pressures Driving Forces Responses Land use practices continuous cultivation deforestation State burning On-site: soil degradation low organic matter contents loss of structure, loss of fertility Impacts Good agricultural practice - mulch tillage - cover crops/rotations -manuring - conservation tillage - irrigation On-site - reduction in water storage capacity - increased soil erosion -reduced infiltration Off-site - pollution of surface waters - effects on regional drainage - flooding Soil Protection Strategy

34 Conclusions: Policy requirements: Baseline for Organic Carbon (OC) content in European Soils urgently needed Baseline for 1990 to be in accordance with international protocols eg Kyoto, IPCC Monitor OC contents (periodically) in the future to maintain soil quality/health OC contents important indicator for soil quality/ health [soil as a C-sink probably less important in short- to medium-term] Organic Carbon Database for Europe (0-30cm): [calculated from the European Soil Database and revised PTR] Most comprehensive data currently available Defines baseline for viz AAAT data ( ), samples for validation ( , 1980s), CORINE LC ( ) Further validation needed eg in N & S Europe Monitoring network needed for medium- to long-term

35 Climate data AAAT day deg C Global Historical Climatology Network (GHCN) Data source Av annual accumulated temperature (AAAT) computed from GHCN temperature data Rasterization Spatial layers derived by rasterization of a Triangulated Irregular Network (TIN) model with weighted distance interpolation, in applying the adabatic lapse rate of 6 deg C per 1000m rise

36 European Soil Monitoring Network 16 x 16 km cell size Level I: 21,760 cells Level II: 2,000 cells Level III: local sites for erosion, sealing, hydrogeologic