Agricultural land classification surveys
Land classification surveys for renewable energy and development projects
Agricultural land classification (ALC) categorises land based on its suitability for food production. In the 1980’s, when ADAS was part of the Ministry of Agriculture, Fisheries and Food, it developed and tested the national ALC methodology and guidelines, which remain in use by Natural England. We remain nationally recognised for our ALC expertise and act as advisors to Defra, Environment Agency and Natural England on soil-related matters.
For landowners, developers and councils, we can provide independent ALC assessments and detailed soil surveys across England and Wales.
What an ALC survey involves
ADAS offers standalone ALC reports or, alternatively, input into environmental impact assessments (EIA) and environmental statements (ES). To grade the land, our surveyors will
- conduct desk studies of published soils, geological and flood risk information
- determine the presence of any recorded detailed ALC surveys that exist on the proposed sites
- calculate site specific climatic data that may affect soils and land classification.
Following the desk-based survey, we will undertake fieldwork to assess the site and soil conditions, which typically involves
- describing the site regarding land use, slope, micro-relief and flood risk
- doing auger borings across the site and digging soil pits if necessary to determine subsoil characteristics
- recording information on soil texture, depth, stone content, drainage characteristics, wetness class and soil structure.
The ALC grades
The ALC system grades land according to how much its physical or chemical characteristics limit long-term agricultural use. The grade of land will depend on climate, site and soil factors. Under the National Planning Policy Framework, planning authorities are required to recognise the benefits of the best and most versatile agricultural land (BMV). As such, planning authorities will seek to protect agricultural land of grades 1, 2 and subgrade 3a.
More information on the ALC gradesHigh-yielding land with little or no limitations for agricultural use
Very good quality agricultural land with minor limitations that affect crop yield cultivations or harvesting
Good-to-moderate quality agricultural land with some limitations on crop choice, timing and type of cultivation, harvesting or the level of yield.
- Subgrade 3a: good quality agricultural land capable of producing high yields of narrow range of arable crops.
- Subgrade 3b: moderate quality agricultural land capable of a narrow range of arable/grass yields.
Poor quality land with severe limitations which significantly restrict the range of crops or level of yields.
Poor quality land with very severe limitations that restrict use to permanent pasture or rough grazing.
Creating an ALC map and report
Using our soil and site observations, we will assign an ALC grading at each auger boring and pit to create an ALC map of the site. This is drafted in the field. We will finalise the map after we have carried out soil sample analysis and a calculation of drought risk. Additionally, our clients will receive an ALC report describing the main factors and limitations found on site. Our summary table of land quality by area will display what percentage of the site belongs to each ALC grade.
We closely follow the specifications set in the Agricultural Land Classification of England and Wales – revised guidelines and criteria for grading the quality of agricultural land, Defra 1988. For multiple sites, we can alternatively provide advanced desk studies or reconnaissance fieldwork to specifically identify lower quality land.
Examples of our ALC work
We completed a major re-survey of 4000 hectares of Welsh farmland to validate the Welsh Government’s Predictive ALC map. It was the largest survey programme in decades. As part of the project, we also produced a range of predicted climate change parameters and conducted a land suitability study for less well-defined crops such as ornamental and energy crops.
For Highways England, we conducted ALC surveys on the A47 Blofield, A47 North Tuddenham, A47 Thickthorn and A47 Wansford. Along with a full ALC survey and report, we provided a detailed soil restoration strategy.
Our ALC surveyors can provide expert evidence for a wide range of large infrastructure projects including rail, road, solar, wind and mixed renewables. We have provided impartial technical expertise on agricultural drainage systems and land restoration. Our in-depth knowledge of the legal and technical aspects of land drainage underscores our excellence in handling disputes.
In 2024, ADAS Soil and Drainage Technical Director and lead for ALC Kirk Hill co-authored the AHDB land drainage guide, which offers best-practice guidance for installation, maintenance and repairs.
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