Across the country approximately 20% of soils on farms are at optimum soil fertility for soil pH, phosphorus (P) and potassium (K).

On Tullamore Farm, results from soil samples taken last December show that 32% of soils are correct for soil pH and are at index 3 or 4 for P and K.

Soil pH is not an issue on the farm. It ranges from 6.4 to 8.0.


P levels are generally high on the farm, which isn’t a surprise given that bulls are being finished on the farm and animal manure is available to spread. Forty-five per cent of soils are at index 4, so P should not be applied to these areas. At index 3, P needs to be applied for maintenance and on grassland can receive 10kg/ha or eight units/ac.

Index 2 and 3 require maintenance and build-up rates of 20kg/ha and 30kg/ha respectively. It should also be noted that on index 1 and 2 soil, P will not be fully available from slurry. It will only be approximately 50% available.


Forty-one per cent of soils are at index 2 for K on the farm. This is common on grassland farms as silage production can result in K depletion.

Index 2 soils will require a maintenance and build-up rate of 45kg/ha of K, while index 1 soils will require 75kg/ha. Index 3 soils require 15kg/ha of K for maintenance.

Target slurry

It might be best to target slurry at soils lower in P and K to increase microbial activity and organic matter levels in the soil. On many farms, slurry is targeted at drier fields, but having enough storage to send slurry where it is needed most is a challenge.

If possible, the fields that need it most should be targeted rather than the drier fields, even if this means spreading a small bit to make room in the tank and waiting until ground dries up in the spring to spread the remainder where it is needed.

It is also important to think about what slurry goes where. Animals on high levels of meal will most likely have a higher P level in their slurry and so this slurry can be targeted at low-P soils.

Slurry testing is important for this reason. For example, on Tullamore Farm the slurry under the finishing bulls is a lot higher in P than the slurry under the cows.

Soil health

Soil organic matter levels are good on the farm, ranging from 5.1% to 13.7%.

The average soil organic matter percentage on the farm is 8.7%.