Soil sampling is an essential task on all farms and should be carried out every three to five years to ensure that work is done to maintain or build soil index levels.

Samples were taken on Tullamore Farm in December. Here, we take a look at the results.

Soil pH on the farm is high and no lime is needed. Soil pH levels range from 6.5 to 8.0 and the majority are over 7.

These soil pH levels are high for grassland and ideally should be at 6.3. There are high molybdenum soils on the farm and ideally these soils should be reading at 6.2.


Out of a total of 22 samples, 10 are in index 4 for phosphorus (P), four are in index 3, five in index 2 and three in index 1.

Soils at index 4 do not require any P. Those in index 3 require a maintenance level of 10kg/ha or eight units/ac.

As P levels go down, the level needed can increase by 10kg/ha for each drop in index.

P and potassium (K) will come from animal manure on the farm and the remainder from artificial fertiliser. It is essential to take account of all sources.


K levels aren’t as good and need work. Levels of K are often low on grassland farms, particularly where silage is being taken off, so it’s important to keep an eye on levels and work to increase them.

Three samples are at index 1, while nine samples are at index 2. Just four samples are at optimum levels for K at index 3, while six are at index 4.

Soils on index 4 do not require additional K, those on index 3 require 15kg/ha or 12 units/ac.

Index 2 soils require K at a minimum of 45kg/ha and those in index 1 require 75kg/ha to build the index.

While fertiliser prices have increased this year, one element that has remained good value is K and this year may be a good time to invest in additions to build levels on low soils.

Compound doesn’t have to be applied in the spring, so it might be a case of applying a little more regularly during the growing season or in the back-end of the year.

Soil organic matter

A test for soil organic matter was also carried out on a selection of samples. Levels are generally high.

The lowest soil organic matter result was 5.1%, while the highest was 13.7%.

These soil organic matter levels are an indication of good soil health, but in the coming months, we will take a deeper look at soil health on the farm, particularly water infiltration capabilities and earthworm activity.