14 August 2026 · Field Guide

How to do a VESS assessment

Visual Evaluation of Soil Structure, VESS, is one of the most useful five minutes a farmer can spend in a field, because it turns something usually left to laboratory bulk density measurements into a test that needs nothing more than a spade and a flat surface, developed and published by Ball, Batey, and Munkholm in 2007 and now used widely across UK soil health schemes.

The five steps of a VESS assessment, at a glance.

What you need

A spade, ideally a square edged one
A flat surface or mat to lay the soil block on, a feed bag works well
A camera or phone, to record each score against a photo

The steps

Dig out an intact block. Cut a block roughly 20cm by 20cm, to the depth of the spade, trying to disturb the internal structure as little as possible while removing it, then lift the block out and place it on the flat surface.
Break the block apart by hand. Starting at the top, gently pull the block apart along its natural lines of weakness rather than crushing or forcing it, since the way it breaks, and how much effort that takes, is central to the score.
Separate the block into layers. Most blocks break into two or three distinct layers or horizons, often with a visibly different structure between the topsoil and whatever lies beneath it, and each layer needs to be scored separately rather than the block as a whole.
Score each layer from Sq1 to Sq5. Sq1 is friable, crumbly soil that falls apart easily into small, rounded aggregates with visible roots and pores throughout. Sq5 is the opposite: dense, compacted material that breaks only into large, angular blocks, has few visible pores, and shows roots confined to cracks between blocks rather than growing through the soil itself. Sq2 to Sq4 sit between these two extremes, and most published guides include reference photographs worth keeping to hand while scoring.
Record the score, the depth of each layer, and a photo, then repeat. A single spade square tells you about one point in one field on one day, so the real value comes from repeating the test at several points, and repeating it in the same spots over successive years to track whether structure is improving or degrading under current management.

A layer immediately below the topsoil scoring Sq4 or Sq5, sitting under a healthier Sq1 or Sq2 topsoil, is one of the most common findings in grazed fields, and usually points to historic compaction from machinery or livestock traffic rather than anything currently visible at the surface.

VESS will not replace the laboratory measurements of bulk density, porosity, or aggregate stability that a proper soil health assessment relies on, but as a five minute field test that costs nothing and needs no equipment beyond a spade, it earns its place as the first thing to do before deciding whether a more detailed, and more expensive, assessment is actually justified.

Back to all posts