Tillage management: Have you soil sampled yet?

Soil sampling is an essential job on all farms, but particularly on tillage farms. Knowing what nutrients are in your soil can reduce fertiliser costs. This is especially important in a year like 2018, when fertilsier prices are approximately €50/t higher than this time last year.

Soil sampling also allows farmers to take a look at soil fertility, which must be at optimum levels to achieve high yields.

Sampling method

The key to a good soil sample is that it is representative. For example, where patches in fields are under-performing, they should be sampled separately.

Soil cores should be taken to a depth of 10cm and at least 20 soil cores should be taken per sample. These samples can be mixed together and sub-sampled.

The “W” pattern is a common method of sampling and can help to get a representative sample. When using this method, it is important that unrepresentative areas are avoided in the field. For example, a farmer should not sample where lime or farmyard manure has been heaped in previous years.


Soil sampling should ideally be carried out when ground is relatively dry. A representative soil sample won’t be achieved when ground is sloppy or frosty.

Nitrates regulations

Soil samples should cover an area of 4ha on tillage land. This figure can be increased to 5ha where soil types or cropping of lands were similar in the previous five years. 5ha samples may apply to grassland farms.

When not to soil sample

Farmers should not soil sample until three-to-six months after a phosphorus or potassium application. Furthermore, soil samples should not be taken within two years of a lime application.