Do soil analysis results determine your fertiliser plan?: Dr Andy Owen, ICL International Technical Manager, on the science of soil testing versus the reality of turf nutrition.

For many turf professionals, soil analysis is the starting point for creating a fertiliser programme.

The process is familiar: take a soil sample, send it for analysis, and use the results to shape nutrient applications. It’s a logical approach, after all, soil tests provide valuable data on pH, nutrient levels, and soil composition.

But is that enough?

While soil analysis is an important tool, it doesn’t tell the full story of turf nutrition. Grass species, climate, and maintenance practices all influence nutrient availability, and a soil test alone won’t account for these real world factors. Understanding when and how to use soil analysis effectively is key to making smarter fertiliser decisions.

What Soil Analysis Tells You – And What It Doesn’t

A soil test provides a snapshot of the chemical composition beneath the turf, typically measuring:

• pH levels – Extremes can impact nutrient availability.
• Cation exchange capacity (CEC) – Indicates the soil’s ability to retain nutrients.
• Salinity – Helps detect potential stressors.
• Macronutrients (N, P, K) and Micronutrients – Highlights potential deficiencies or excesses.
• Organic matter content – Affects microbial activity and soil health.

These insights help identify imbalances, but they don’t necessarily show what’s available to the plant.

Turf nutrition is more than just soil chemistry, it depends on how nutrients interact with the root system, climate, and ongoing maintenance practices.

For example:

• A soil test might show acceptable phosphorus levels, yet if the turf exhibits deficiency symptoms, poor root uptake (not a lack of phosphorus) could be the real issue.
• Nitrogen recommendations should be based on plant demand, not soil tests, since nitrogen is highly mobile and influenced by temperature and growth cycles.
• Soil pH is a critical factor, correcting pH imbalances can improve nutrient availability more effectively than applying additional fertiliser, but this is not simple for all soils

So, while soil analysis provides a useful benchmark, fertiliser decisions should go beyond the numbers.

What Does the Research Say?

Agronomists and researchers agree that soil testing is most valuable when used as part of a long-term strategy rather than as a standalone guide. Studies and field experience highlight key considerations:

• Soil analysis is most useful for tracking trends over time – One-off tests can be misleading, so repeated testing is essential for accuracy.
• Visual assessments matter just as much as data – Turf colour, growth rate, and stress indicators provide real-time feedback on nutrient status.
• Fertilisation should be responsive, not prescriptive – Climate conditions, aeration, and root development all affect nutrient uptake, making a flexible approach more effective.

By combining scientific analysis with practical field observations, greenkeepers can make fertiliser decisions that reflect real-world turf performance, not just lab results.

Why Do People Rely So Heavily on Soil Analysis?

The idea that soil testing directly dictates fertiliser programmes has been reinforced by a few common factors:

• Industry Tradition – Many turf professionals are taught that soil testing is the first and most important step in fertiliser planning.
• Simplicity – A lab report provides clear numbers, making it seem like a definitive guide to nutrient applications.
• Supplier Influence – Some fertiliser recommendations are based on soil test results interpreted by suppliers, sometimes leading to unnecessary or imbalanced applications.

While soil testing should inform fertiliser decisions, it shouldn’t dictate them in isolation. A more dynamic, responsive approach leads to better long-term turf health.

How to Build a Smarter Fertiliser Plan

Instead of basing fertiliser applications purely on lab results, a more effective strategy considers both science and on-the-ground observations:

• Observe turf performance – Regularly assess turf colour, growth, and stress response to identify nutrient needs.
• Factor in environmental conditions – Climate, rainfall, and soil drainage affect nutrient availability as much as soil chemistry.
• Use soil analysis for long-term monitoring – Track trends over time rather than making reactive decisions based on a single test.
• Match fertiliser inputs to grass species – Different turf types have unique nutritional demands that go beyond what’s in the soil.
• Balance fertilisation with maintenance – Aeration, irrigation, and organic matter management all influence how well nutrients are absorbed.

This approach ensures that fertiliser inputs are aligned with real turf needs, rather than simply following numbers from a report.

Balancing Science with Practical Turf Management

Soil analysis is a valuable tool, but it’s not the whole story. Fertiliser planning requires a mix of scientific data, turf observations, and agronomic expertise to make informed decisions.

Rather than treating soil test results as a prescription, they should be seen as one piece of a larger strategy, working alongside field knowledge, environmental conditions, and real world turf performance.

At ICL, we believe in evidence based fertiliser planning, using soil data as part of a bigger picture, not the sole deciding factor. By taking a balanced approach, turf professionals can achieve long-term health and resilience, not just short-term corrections.