Soil Sampling: Prepare for Spring 2024

With 213 different soil types in Ireland, farmers must remain attuned to fertility levels which can, in several instances, vary from field to field.

As tillage farmers prepare for Spring 2024, all are required to undertake compulsory soil testing, as set out in the EU’s Nitrates Directive Programme (2022-2025).

Between now and February/March represents the optimum time to take a soil sample, thus providing farmers with an up-to-date picture as to how much or how little fertiliser will be required. New tests should be compared with past results to determine changes or consistencies in soil fertility.

Samples should be taken at least three months after the last application of Phosphorus (P) and Potassium (K) or two years in the case of where lime has been applied.

Identifying areas of low soil fertility within paddocks will lead to savings in fertiliser costs while also establishing where additional fertiliser will be needed.

Using a soil corer, a minimum of 20 soil core samples must be collected from a sampling depth of 100 millimetres (10cm, 4 inches) with a sample taken every two to four hectares (5 to 10 acres).

Achieving consistency in soil sampling depth is critical, according to Teagasc’s Mark Plunkett given that Phosphorous tends to rest in the “top few centimetres of the soil. If we take shallow soil cores, then we will get a false reading for Phosphorus so it’s very important that you get the full four-inch core every time because we are basing our advice for the next three to five years on this soil sample”.

Samples must be taken from areas with differing soil types, with a previous cropping history, drainage, slope or persistently poor yields.

It’s essential to avoid the following areas when sampling: ditches, old fencing, around drinking troughs and ring feeders, along with urine and dung patches or areas where fertiliser, manure or lime have been heaped or spilled previously.

A sample normally consists of 0.25 to 0.5 kg of soil, which is taken to represent the entire sampling area or field.

A representative soil sample is then recorded by walking in a ‘W’-shaped pattern across the sampling area.

The soil sample is then placed in a soil box to avoid contamination, with the field number and advisor code then written on the box with a permanent marker to ensure the tested paddock is named and readily identifiable.

Taking a minimum of 20 soil cores, the cores are mixed together to create a representative sub-sample for analysis, ensuring that the soil sample box is full. From there, the sample is sent to the lab for analysis.

In order to achieve optimum grass growth and crop yield, care must be taken to ensure that the soil contains the main nutrients needed to succeed.

Target Fertilisers recommends soil sampling every to three to five years to ensure your soil is receiving the appropriate nutrient levels, while also revealing any nutritional deficiencies.

When putting a fertiliser plan in place, it’s also important to take into account the offtakes of nutrients from the soil by the animal or the crops. According to Teagasc, a milking cow can retain up to 19kg/ha of P and 36kg/ha of K while a cereal crop retains an average of 3.8kg/ha of P and 12.9kg/ha when straw is removed.

Target Fertilisers has an extensive range of high quality fertiliser products with over 60 blends and compounds available. Target will also provide special bespoke blends on request outside their standard product listing. All of Target’s fertiliser products are granular and meet strict quality controls on chemical analysis, moisture content, granule size, hardness and density.

More information

For more information on utilising your soil sample results and developing a farm fertiliser plan for 2024, please contact a member of the Target Fertiliser team here.