When to Sample Soil and What Is Needed

Soil testing is a valuable way of understanding the chemical, physical and biological status of soil that helps inform crop management decisions.

One of the main benefits is that it can help guide nutrition requirements and support fertiliser choice, helping to ensure crops receive the necessary nutrients for optimised productivity.

What do samples provide?

Before exploring what is needed and when for soil sampling, it is important to understand what it is that soil sampling provides:

Further information can be found on the ADHB website.

1. Nutrient evaluation

• An understanding of what nutrients are present in the soil and to what extent

2. Biological evaluation

• An account of living organisms, such as bacteria and fungi, that contribute to crop nutrition, recycling, and influence soil structure

3. Chemical and physical evaluation

• Information on soil properties such as soil pH, organic matter, and soil texture

Long term benefits of soil sampling

Regular soil sampling provides multiple benefits to farmers, allowing for consistent monitoring and enhancement of soil health, leading to long-term fertility. By understanding the soil’s exact needs, farmers can optimise fertiliser use, resulting in cost savings and higher crop yields.

These frequent tests also promote sustainable farming, reducing over-fertilisation and environmental harm. They pre-emptively identify potential soil issues and, with accumulated data over time, guide informed farming decisions from crop rotation to soil conservation.

Furthermore, these analyses aid in adjusting soil pH and understanding physical attributes like compaction, ensuring an environmentally responsible farming approach with reduced runoff into water systems.

When to soil sample

Although soil samples can be taken at any time of the year, certain periods can be advantageous and creating an action plan for soil testing is advised.

Late summer through to winter is typically the most popular time of the year to test, with –

• Late summer and early autumn provide time to change the pH of the soil before crops are planted

And

• Quieter winter months offer a good opportunity to analyse the state of soils and consider any adjustments to maximise fertility and crop potential

Although samples can be taken at any given time in any season, there are factors to consider:

• Avoid sampling within two years of applying lime or within two months of applying a compound fertiliser, manure or more than 50 kg/ha nitrogen
• If sampling repeatedly and annually, it’s important to collect samples at similar times of the year to ensure more accuracy in results

It is advisable to take samples before any manure or anaerobic digestate is applied, as this will sway the results significantly.

What is needed?

In comparison with other jobs on arable and mixed farms, soil sampling requires a limited amount of technology and scientific knowledge.

• The only equipment required for carrying out a soil sample is a standard soil-sampling auger, also known as a corer and clean bags to hold and transport each sample
• The recommended bags are sealable, clear-plastic sandwich bags that can be labelled with a waterproof maker pen
• These can then be sent off to your preferred supplier to analyse the samples and provide you with analysis. Speak to your local agronomist for advice on this

How much soil is sampled?

Samples typically consist of 0.25 – 0.5 kg of soil which are taken to represent the entire sampling area or field.