Agricultural Land Classification

Best and Most Versatile (BMV) land is defined in the NPPF as land in Grades 1, 2, and 3a of the Agricultural Land Classification system. This land is the most flexible, productive, and efficient in response to inputs. The NPPF states that where significant development of agricultural land is demonstrated to be necessary, local planning authorities should seek to use areas of poorer quality land in preference to that of a higher quality. The loss of BMV land is treated as a significant material consideration in planning decisions.

Natural England publishes provisional ALC maps covering all of England, available through the MAGIC mapping service. However, provisional maps are based on reconnaissance surveys from the 1960s and 1970s and are not sufficiently detailed for planning purposes — they do not distinguish between Grade 3a and 3b. For a planning application, a detailed post-1988 ALC survey is usually required to provide site-specific data at a resolution that planning authorities can rely upon.

No. The NPPF does not impose an absolute prohibition on developing agricultural land, but it creates a strong presumption in favour of protecting BMV land. The decision-maker must weigh the benefits of the development against the harm caused by the loss of agricultural land. If lower-quality land is available in the area, development on BMV land will be harder to justify. Where BMV loss is unavoidable, the proportion of land affected and any measures to preserve soil quality will be relevant considerations.

This is the critical distinction for planning purposes. Grade 3a is 'good quality' agricultural land capable of producing moderate to high yields of a narrow range of arable crops or moderate yields of a wide range of crops. It falls within the BMV category and receives policy protection. Grade 3b is 'moderate quality' land capable of producing moderate yields of a limited range of crops, mainly cereals and grass. It is not BMV land and does not benefit from the same level of protection. The provisional ALC maps do not distinguish between 3a and 3b, which is why a detailed survey is essential.

Winter surveys are possible but may have limitations. Waterlogged soils can make augering difficult or impossible, and the assessment of soil wetness class — a key factor in ALC grading — may be less reliable when soils are at or beyond field capacity. Where winter survey is unavoidable, the surveyor should note any limitations and may need to return in spring or summer to confirm wetness assessments. Most experienced surveyors can work year-round with appropriate caveats.

Natural England is a statutory consultee for planning applications involving the loss of 20 hectares or more of BMV agricultural land. Below this threshold, the local authority makes its own assessment, but it may still consult Natural England on significant cases. Natural England will also respond to pre-application enquiries about agricultural land quality, which can be useful for establishing the principle of development before investing in detailed site surveys.

The surveyor uses a Dutch or Edelman auger to examine the soil profile at each survey point, typically boring to a depth of 1.2 metres. At each point, the surveyor records topsoil depth and texture, subsoil characteristics, stoniness, presence of slowly permeable layers, depth to gleying (waterlogging indicators), root depth, and any limiting factors. Some samples may be sent to a laboratory for particle size analysis to confirm field texture assessments. The survey density is typically one boring per hectare for detailed assessments.

Climate is a fundamental factor in ALC. The grade of land reflects not just soil quality but also the climatic conditions that determine how productively the soil can be farmed. Key climate parameters include average annual rainfall, accumulated temperature above 0 degrees Celsius (growing degree-days), and the number of field capacity days (days when the soil is too wet for agricultural machinery). Land in wetter, cooler areas of the country may receive a lower grade than identical soil in a warmer, drier region.

To a limited extent. Drainage improvements can address soil wetness limitations, and soil management practices can maintain or improve soil structure. However, the ALC grade reflects inherent soil and climate characteristics that cannot fundamentally be changed. Land graded 3b due to heavy clay texture and high rainfall cannot be improved to 3a through management alone. The assessment is based on the current condition of the land under good management practices.

A soil handling strategy — sometimes called a soil management plan — sets out how topsoil and subsoil will be stripped, stored, and reused during construction. Planning authorities often require one as a condition of permission for developments on agricultural land, to ensure that the soil resource is not degraded or wasted. The strategy should follow Defra's Construction Code of Practice for the Sustainable Use of Soils on Construction Sites (2009) and specify soil stripping depths, stockpile locations, storage durations, and reinstatement procedures.