Environmental offsetting for farmland conservation. Arne Grønlund Bioforsk jord og miljø

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1 Environmental offsetting for farmland conservation Arne Grønlund Bioforsk jord og miljø

2 Farmland in Norway Arable land Cultivated to normal ploughing depth (20-25 cm) and suitable for cultivation of arable crops and grass Superficially cultivated land Cultivated in the surface and suitable for cultivation of grass for mowing Infield pasture Cleared for pasture, not suitable for arable crops or mowing ha ha ha 1.1 mill ha

3 Cultivated and cultivatable land Farmland=cultivated land Arable land Superficially cultivated Infield pasture Some areas can be cleared for pasture or superficially cultivated Uncultivated land Cultivatable (potential arable land, reserve land) Uncultivatable not suitable for cultivation to arable land because of climate, poor soil quality and steep terrain

4 Options for offsetting (According to Ministry of Transport) Movement of soil from development area to compensation (receptor) area Conventional cultivation (in situ) Converting uncultivatable land to arable land by movement of soil Improved soil quality on arable land by movement of soil Conversion of uncultivated land to arable land Conversion of uncultivated land to infield pasture or superficially cultivated land New method little experience Ordinary method Less relevant

5 Benefits and disadvantages Conversion of uncultivatable land to arable land by movement of soil Improved soil quality on arable land by movement of soil Conversion of uncultivated (cultivatable) land to arable land Conversion of uncultivated land to infield pasture or superficially cultivated land Small farmland area lost Expensive (3-4 mill NOK/ha) Risk of degradation Large farmland area lost Expensive (1-2 mill NOK/ha?) Lot of experience Cheaper (< NOK/ha) Loss of reserve land Cheap (< NOK ha) Large land recources Only relevant for grass Large differences in costs

6 What option should be choosen? Converting uncultivatable land to arable land by movement of soil Improved soil quality on arable land by movement of soil Convertion of uncultivated land to arable land Convertion of uncultivated land to infield pasture or superficially cultivated land High soil productivity Suitable uncultivatable receptor areas available High soil productivity Uncultivatable receptor areas not available Low soil productivity Large reserves of cultivatable land

7 Areas suitable for cultivation, 1000 ha Current agric. land Total Suitable for grain 400 Arable Grassland, mineral soil 400 Grassland, organic soil 65 Superficially cultivated 35 Infield pasture 190 Cultivatable reserve land <200 ~ Not surveyed >1000 Offsetting option Movement In situ cultivation

8 Challenges for movement of soil Maintain original soil stratification Select suitable receptor areas Avoid soil degradation

9 Stratification of arable soil Ap horizon Surface soil - plough layer B horizon C horizon Weathered subsoil with developed soil structure Little affected by soil forming processes

10 Original cultivated soil Ap horizon B horizon cm cm C horizon Bedrock Movement of soil Ap horizon B horizon Land levelling with surplus stones from road construction + subsoil Fjellgrunn Fjellgrun n Bedrock

11 Requirements for receptor areas Climate Distance: Short distance to development area Close to existing arable land Topography: Not considered as cultivatable Flat terrain - not too steep No area conflicts: Not worthy of preservation No other planned development Examples: Shallow soil Forest soil Superficially cultivated Abandoned landfills, sand/gravel pits Interested landowner

12 Risk for soil degradation Especially vulnrable in wet condition Physical degradation Soil compaction Soil structure damage Soil erosion No protection by vegetation Excavator - not bulldozer Risk for reduced soil productivity Spreading of pests and weed

13 Movement of soil no guarantee for success Physical degradation Destroyed soil structure Transported soil in Vestby

14 Size of compensation area Compensation area: Less productive than the developed area Should be larger to maintain the productivity Conventional cultivation Movement of soil Compensation area Expected yield: ~ 70 % of existing farmland Size: ~ 150 % of developed area 0-~ 30 % yield reduction Size of receptor area=size of developed area Additional cultivation of cultivatable soil: 0-~ 50 % of developed area No exact answer exists

15 Excaple: New E18 from Vinterbro to Østfold Impossible to build a new highway without touching farmland Intention to conserve farmland by movement of soil

16 Final remarks Only relevant when development of farmland is unavoidable Cultivation and movement of soil Cannot completely compensate the farmland lost by development No justification to avoid protection of farmland