Farm Ireland

Tuesday 20 March 2018

Soil testing crucial now

Mark Plunkett

NOW IS the ideal time to identify parts of your farm that require up-to-date soil analysis and plan to have soil samples taken over the coming months. This is vital to ensure that crop nutrient requirements are satisfied -- and it will help avoid either under-fertilising or over-fertilising crops for next year.

Fertilisers now form a large proportion of production costs and will have a large influence on farm productivity and profitability.


Always remember, soil test results are only as good as the soil sample taken.

It is essential that soils are sampled correctly and taken with a suitable soil corer to the correct sampling depth.

The following should be considered when doing a sample:

  • Sampling areas should be 2-4ha in size;
  • Avoid any unusual spots such as old fences etc;
  • Sample the top 10cm of soil with a suitable soil corer;
  • Leave four to six months between sampling and organic manure or chemical phosphorus (P) and potassium (K) applications;
  • Take representative soil sample (follow a 'W' soil sampling pattern);
  • Take around 20 cores to make up the soil sample.


Fertiliser efficiency will be reduced where the soil pH is below the optimum. To maximise both production and economic response from applied N, P and K fertilisers, it is essential to lime soils to increase soil pH to target levels.

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Derogation farms

Soil samples on derogation farms need to be taken every four years from a maximum 5ha sampling area. Farmers who applied in 2007 for a derogation and have also applied in 2010 must have soil sample results for the whole farm by December 31, 2010.


Nutrient management was a measure under REPS which provided the farm with a five-year nutrient management plan. In addition, this plan satisfied requirements under cross compliance and fertiliser planning.

A large number of REPS 3 participants will finish their contract over the next 16 months. All farmers who exit from REPS 3 must now be compliant with the Nitrates regulation fertiliser limits.

These farms should now be retested to check soil fertility levels and plan fertiliser requirements for the next five years.

For farms not in REPS, a fertiliser plan will have to be prepared annually to satisfy the cross-compliance requirements.

Continuous tillage

For this year, 50pc of continuous tillage soils need be analysed for soil organic matter by December 31 and the other 50pc must be tested by December 31, 2011.

Take one sample every 4ha, or, where there is similar soil type and cropping history, the sampling area can be increased to 8ha (link sampling areas to LPIS numbers).

Soil needs only to be sampled once every 10 years as organic matter levels change slowly over time.

Where soil organic matter levels are above 3.4pc (2pc soil organic carbon), there are no remedial actions required.

Where soil organic matter levels are below 3.4pc, the grower must seek advice from a cross-compliance or Farm Advisory Service adviser, who will determine what -- if any -- remedial action is required.

The FAS adviser will carry out a field assessment, taking into account crop rotation, soil type and soil structure. Where high crop yields are being achieved and there is no evidence of soil structural problems even though the soil organic matter is less that 3.4pc, there is no requirement to carry out remedial action.

Where low crop yields are being produced or where soil structural problems are present, it makes sense to take this information to improve soil organic matter levels (chopping straw, organic manure application, min till, etc).

The aim is to maintain soil organic matter where soils are below the threshold value (3.4pc). The best time to take samples is immediately after the crop has been harvested. Contact your local Teagasc adviser to organise the taking of samples for both nutrient and soil organic matter analysis.

Irish Independent