Study shows optimal soil phosphorus reduces fertiliser derived emissions

Grass

Getting soil phosphorus (P) levels right through a fertiliser programme can significantly reduce emissions of nitrous oxide (N2O), a potent greenhouse gas, a scientific paper from Teagasc shows.

The paper from researchers at the Teagasc Environment, Soils and Land-Use Department in Johnstown Castle, County Wexford has just been published in the scientific journal, Nature Scientific Reports. It concludes that increasing soil phosphorus to the recommended level for grass productivity reduces fertiliser derived N2O emissions in intensively managed temperate grasslands.

Head of the Teagasc Environment Research Department, Dr Karl Richards said: “The paper shows that there are reduced N2O emissions from fertiliser applied to soils where they have the recommended agronomic optimum soil phosphorus levels. 

"Farmers who improve soil fertility for agronomic benefits, can also reduce N2O emissions. This represents a win-win for the farmer and environment.”

Postdoctoral Researcher with Teagasc, Amanuel Gebremichael, outlined the main findings: “We found that a long-term increase in soil phosphorus from fertiliser significantly decreased N2O emissions from field plots. In addition, keeping the soil P at the optimum level has the potential to further reduce N2O emissions due to higher grass N uptake through increased yields.”

The results showed that applying 45 kilograms of P per hectare per year increased soil test phosphorus from index 1 to index 3 and significantly reduced N2O emissions by 42%. The study highlights that achieving agronomic soil fertility targets can reduce greenhouse gas emissions and maintain agricultural production.