A large deficit in lime application on grassland farms continued last year, Teagasc's 2022 soil test results found.
The results show that 47% of dairy farm samples and 57% of drystock farm samples have pH levels below the target pH of greater than 6.3.
On tillage farms, overall soil pH levels are higher, yet 39% of soils still remain below the target soil pH of greater than 6.5, Teagasc has said.
Early indications suggest that lime use in 2022 will exceed 1 million tonnes for the second year in a row, according to Teagasc.
Soil and plant nutrition specialist at Teagasc Mark Plunkett said: “With 39% to 57% of our soils requiring lime application, it is now a priority on grassland and tillage farms to apply lime based on soil analysis to optimise soil pH."
Overall, soil fertility showed some positive trends, with a stabilisation in the proportion of soils with an overall optimum soil fertility for pH, phosphorus (P) and potassium (K) on both drystock and tillage farms, while improvement in soil fertility was shown on dairy farms in 2022.
This, Teagasc said, follows two years of decline in optimum levels of soil fertility on grassland farms.
All farm types showed an improvement in soil P and K fertility, with the exception of tillage farms, where soil K levels declined slightly for the first time in 11 years.
The soil samples from dairy farms indicate a 4% increase in soils with optimum soil fertility to 20% in total.
Soil with optimum fertility on tillage farms increased slightly to 19% currently, while soil fertility remained unchanged on drystock farms at just 13% within the optimum range for pH, P and K.
Soil fertility researcher at Teagasc, Johnstown Castle, Dr David Wall said: “These soil test results indicate that national soil fertility levels have broadly held stable.
"However, we must be conscious of what has happened with fertiliser use on farms over the past year.
"Unfortunately, if reduced fertiliser use continues during 2023, it will likely lead to further running down of soil nutrient reserves and declining soil fertility.
"These potential reductions in soil fertility will only be detected when these fields are re-sampled in a few years’ time."
The impact of reduced use of P and K in 2022 is likely to show as reduced fertility in future years if this reduction is not reversed, he argued.
Head of environment knowledge transfer in Teagasc Pat Murphy said that preparing and implementing a nutrient management plan has never been more important.
"Plans should be based on up-to-date soil samples, should focus firstly on correcting pH, secondly on getting the most from slurry and manures by identifying where it is needed most and thirdly, particular attention should be paid to using fertiliser types that reduce emissions and provide the best value for money," he said.