Taking soil samples correctly

As we are heading into the major soil sampling season it's important that soil samples are taken correctly, e.g. to the correct soil sampling depth of 10cm & a representative soil sample each time. Mark Plunkett, Teagasc Soil & Plant Nutrition Specialist outlines what's required for perfect results.

Now is the ideal time to identify parts of your farm that require up to date soil analysis and aim to have soil samples taken over the coming weeks / months. This is vital information to ensuring that crop nutrient requirements are satisfied and will help avoid either under fertilising / over fertilising crops for 2021. Taking good soil samples will provide a good foundation for the efficient use of Lime, Slurry / FYM and Fertilisers.

Take a good soil sample

It is essential that soils are sampled correctly and taken with a suitable soil corer to the correct sampling depth of 10 cm. This is important as soil results taken today will be the basis to nutrient applications for the next 4 to 5 years on your farm.  Soil phosphorus (P) tends to accumulate in the top few centimetres of soil in grassland. Incorrect sampling depth will result in an inaccurate soil P reading, especially when sampling is too shallow. For soil test results to be comparable over time they must be sampled to the correct depth on each sampling occasion. Ensure you have a good soil corer and only take samples under suitable soil conditions that allow for full depth coring.

Have soil samples taken for the whole farm. Unless you know what is already in the soil, it is impossible to know how much fertiliser it needs. Therefore, by taking soil analysis and putting the results into practice, the fertiliser programme can be tailored to the needs of the soil and the crop. Repeating soil analysis over time (3 to 5 years) is also critical to monitor the effectiveness of the farm fertiliser strategy.  

The 10 Steps to better soil sampling can be found here  https://www.teagasc.ie/crops/soil--soil-fertility/soil-analysis/

Guidelines for taking a soil sample:-

• Soil sampling areas should be 2 – 4ha in size
• Take representative soil sample (Follow a ‘W’ soil sampling pattern). Avoid following lines of regular machinery traffic
• Avoid any unusual spots such as old field boundaries etc..
• Sample the top 10cm of soil with a suitable soil core
• Leave 3 - 6 months between sampling and P & K applications
• Leave 2 years between sampling and lime applications
• Take approximately 20 cores to make up the soil sample

Prepare a soil sampling map and label samples.

In this short clip, Mark runs through why its so important to be testing your soil and what is the best way to do it.