90% of Irish soils have either a lime, Phosphorous (P) or Potassium (K) requirement, which impacts on overall farm productivity, according to Teagasc Soil and Crop Nutrition Specialist Mark Plunkett.

“Only 10% of grassland soils have the right levels of nutrients to maximise grass production on an annual basis.

“Grassland farms can produce more grass by just addressing the lime deficit,” he said.

Speaking at the Fertiliser Association of Ireland Spring Scientific Meeting, he said there is a large lime requirement on the vast majority of farms.

Teagasc soil test results show that over 66% of Irish farms have a low pH and this is having a negative impact on the production capability of this land, Plunkett said.

Percentage of farms with a low pH
  • 64% of dairy farms
  • 67% of drystock farms
  • 55% of tillage farms

Plunkett also said that Phosphorous (P) continues to decline with 61% of soils in index 1 and 2.

The fall in soil P has occurred due to changes in legislation and a reduction in the use of artificial fertiliser.

“Irish farmers have to put a fertiliser programme in place to replenish the P that has been taken out in harvested crops,” he said.

However, despite the decline in P levels, he said that there is a good availability of Potassium (K) in soils.

“Irish farmers are using slurry more efficiently on the grassland farms. There has been a slight improvement in K levels. A lot of soils are index 3 for K,” he said.

Addressing the problem

Plunkett said that the first element farmers should focus on is lime, as correcting the soil pH will free up essential nutrients such as P and K.

Grassland soils should aim to have a pH of 6.3, while tillage farms should aim to target a pH of 6.5.

The Teagasc specialist also said that farmers should target the use of organic manures on fields which have low fertility, as this is the cheapest way of putting key nutrients back into the ground.

When organic manures are not available, he said that farmers should apply P and K through artificial fertilisers.

The Teagasc representative also said that farmers should make more use of soil sample results.

Environmental schemes have a big influence on the amount of soil sampling that happens on Irish farms. GLAS is the big driver at the minute, as it is a mandatory part of the scheme.