Agricultural Land Classification Workshop

Defra has recently published an update of the Agricultural Land Classification (ALC). The new Predictive ALC map replaces the outdated Provisional ALC map. It has been remodelled using the best available soils data from LandIS. The ALC System for England and Wales grades the inherent quality of farmland for agricultural use.

The system was developed in the mid-60s to map the distribution of agricultural land quality, across England and Wales, to a common standard. This was to ensure scarce, high-quality land could be protected from loss to development, through the planning system - one of the first ‘ecosystem services’ approaches in the UK.

It provides a framework for classifying farmland from Grade 1: excellent quality, to Grade 5: poor quality. Updates to the ALC methodology in 1988 included the sub-division of Grade 3, into Sub-grades 3a and 3b, introducing the important distinction of Best and Most Versatile (BMV) agricultural land. BMV land comprises Grades 1, 2 and 3a, and is given a degree of protection in planning.

In this workshop we will explore the new predictive ALC map covering what has changed compared to the withdrawn Provisional ALC map, how this new map can be used and its limitations. This workshop is aimed at users of the ALC map including Local Planning Authorities, consultants, landowners and environmental agencies.

Discussion Points

The workshop will cover the following. A full agenda will follow prior the meeting.

• A brief history of ALC
• The Provisional ALC and the new predictive ALC map - including methodology, use and limitations.
• Appropriate use of the new Predictive ALC map in planning - The Predictive ALC map is intended for strategic and indicative use only. Users should understand when the map is appropriate to inform early plan‑making or site screening, and when a detailed, field‑based ALC survey (to 2025 Guidelines) is required.
• Understanding differences from the Provisional ALC map - Users may notice changes in ALC grade compared to the withdrawn Provisional ALC map. The workshop will examine why mapped grades may have improved or declined. The ALC remains a strategic scale map, and is not accurate at the field scale.
• Interpretation of Subgrades 3a and 3b - The new ability to visually distinguish Subgrade 3a (BMV) from 3b (non‑BMV) on a national-scale map is a major enhancement. Users may need clarity on how confidently this distinction can be relied upon at national scale, and why site‑specific surveys remain essential.
• The future of ALC

Lunch will be provided. Please inform us of any dietary requirements at the checkout when you register for this event.

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