Getting Under the Surface: How to Assess Soil Structure

Healthy soil structure is the foundation of good crop and grass growth. Soil structure refers to how particles such as sand, silt, clay and organic matter, and the spaces between them, form aggregates or clumps. These aggregates influence aeration, drainage and how easily roots can grow and access water and nutrients. Soils with a good structure support robust plant growth, whereas compacted or degraded soils can restrict roots and cause poor drainage or waterlogging.

Assessing soil structure is straightforward. One well-known method used by farmers and land managers is the Visual Evaluation of Soil Structure (VESS). It is quick, inexpensive and can be done in the field using only a spade and careful observation.

Step by Step: How to Carry Out a VESS Soil Structure Assessment

1. Surface assessment
   Look at the grass sward or crop cover. Patchy vegetation, surface water, poor coverage or evidence of soil damage such as deep wheelings or poaching may indicate soil structure problems beneath the surface.

2. Extract a soil block
   Dig a spade-sized block of soil about 30 centimetres deep. Cut down on three sides and leave one side undisturbed, then lever the block out and lay it on a tray or sheet with the undisturbed side facing up. If the block crumbles easily, dig a second block next to it for comparison.

3. Inspect the soil block
   Gently open the block by hand to expose the soil profile. Look for horizontal layers with differing structure. Focus on the poorest or most compact layer, called the limiting layer, and record its depth for reference.

4. Break the soil into aggregates and evaluate
   Use your hands to break the soil gently into clumps or aggregates. Examine how easily the aggregates break up, their shape, porosity and the presence of roots. These characteristics indicate soil quality and structure.

5. Assign a VESS score
   The VESS scoring system is as follows:

   • Score 1–2 (Good): Soil crumbles easily with small, rounded aggregates, good porosity and numerous well-distributed roots. No immediate management changes are needed.

   • Score 3 (Moderate): Aggregates are firmer, pores less visible and root distribution is sparser. Avoid traffic on wet ground and consider reviewing cultivation practices.

   • Score 4–5 (Poor): Aggregates are large, angular or platy, hard to break, with few roots and poor porosity. This indicates compaction or degraded structure. Interventions such as aeration, drainage improvement, adjusted cropping or reduced soil traffic may be necessary.

6. Follow-up and reassessment
   After scoring, decide on management actions. Reassess soil structure periodically, especially after heavy use, cultivation or extreme weather. On grassland, assess every two years; on arable land, reassess after each rotation.

Why Soil Structure Matters

Good soil structure is important for several reasons:

• It allows air and water to move through the soil, which is essential for root growth, drainage and nutrient uptake.

• It reduces the risk of compaction, waterlogging, surface capping and runoff, which can affect yield and productivity.

• Well-structured soils are more resilient to wet or dry conditions, reducing the risk of damage during adverse weather.

• Assessing soil structure helps land managers target the worst-performing layers first, making soil management more effective and efficient.

By making soil structure assessment a routine part of farm management, farmers can maintain and improve productivity, sustainability and resilience over time.

Practical Tips

• Assess soil when it is moist but not too wet or dry. This makes it easier to break aggregates by hand and avoids misinterpreting dry soil as compacted.

• Compare soil from different parts of the field, such as corners or frequently trafficked areas. This helps recognise variation and identify problem spots.

• Repeat assessments after major management changes, such as tillage, drainage work or heavy traffic, and after seasonal extremes to monitor soil response.

Visual Evaluation of Soil Structure is a way of assessing soil structure which is an indicator of soil health. All you need is a spade and a copy of the scorecard.

​AHDB have produced a guide to assess soil structure, it can be downloaded here.
SRUC have also produced a guide which can be downloaded here.

​If you decide to assess your soil using VESS scores you need to ensure that the same person does the VESS score as it is based on judgement.