Teagasc’s Gary Lanigan has highlighted a number of mitigation measures that can be taken by farmers to reduce greenhouse gas (GHG) emission rates.
Teagasc continues to amend the marginal abatement cost curve (MACC) linked to GHG emissions produced by Irish agriculture.
This initiative is underpinned by ongoing research across myriad aspects of land use.
The work is undertaken with the aim of identifying ways in which Irish farmers can successfully reduce the carbon footprint of their businesses, while also tackling the challenge of ammonia and other related emissions.
Lanigan presented the latest MACC-related updates, courtesy of his recent presentation to a ‘spring seminar’, hosted by the Fertilizer Association of Ireland.
The Johnstown Castle-based scientist confirmed that Irish agriculture is a significant source of GHG emissions.
However, the sector also mitigates the impact of these processes given the ability of soils to sequester significant amounts of atmospheric carbon.
Sources of GHG emissions include: the methane produced by ruminant animals; the nitrous oxide emitted by soils; primarily associated with the application of chemical nitrogen, and the methane emitted by slurry and other organic manures.
Ensuring that soils are continuously maintained at their optimal pH value is highly important. This can be achieved through regular soil testing and the addition of lime.
The Teagasc scientist highlighted the strong link between soil pH values and phosphate availability.
“Research has confirmed that soil pH values determine the availability of many soil nutrients.
“Phosphate is particularly important in this regard. Our research indicates that active phosphate levels in soil impact directly on the level of nitrous oxide emissions.
“Phosphate encourages bacterial growth in spoils relative to fungal populations. We know that fungi are actively involved in the production of nitrous oxide within soils.”
Lanigan also indicated that the interaction between soil pH and available phosphate levels may well have an influence on soil sequestration levels.
Turning to chemical nitrogen (N) applications, Lanigan reviewed the work that had been carried out, researching the impact of protected urea.
“We know that coating urea with the urease inhibitor, NBPT, acts to significantly reduce nitrous oxide emissions. However, the addition of a second urease inhibitor, DCD, will act to bring emission values down to almost zero levels.”
Lanigan explained that DCD is actively included within the body of a urea granule, it is not just a coating.
“DCD is also included within the official inventory listings complied by the department of agriculture.
CAN is also a very valuable nitrogen source. It can be put to best use within a tillage scenario.
Chemical fertiliser regimes
Chair of the European Fertiliser Blenders’ Association (EFBA), Peter Scott, told the seminar that the world of crop nutrient management must be expanded beyond three core inputs: N, potash (K) and phosphate (P).
“Plants require a significant range of nutrients, including trace minerals. This requirement must be reflected in the offerings made available by the fertiliser sector,” he said.
According to Scott, the basic starting point to all of this, is soil testing and analysis that reflect the comprehensive fertiliser requirement of specific crop.
“In reality, this is not an expensive process. Most of the cost is entailed in getting representative soil samples compiled.
“This is equally relevant whether, the soil is tested for a small or large number of attributes.
“Fertiliser applications should also reflect the end use to which a specific crop will be put,” he said.
Scott foresees a future within which farmers will be able to utilise bespoke blends containing a range of micro crop nutrients, formulated to meet the specific needs of individual crops.
He specifically referenced the link that exists between fertiliser application and the issues of crop yield, quality and environmental sustainability.
“Enhancing animal health is a key output that fertiliser programmes can also address. But, we have got to go beyond a focus on specific crop nutrients.
“[E.g.,] high potash levels in forages has been linked to metabolic disorders in dairy cows when fed during the dry period.
“This issue is not solely about the levels of potash in a forage. Rather it has everything to do with the ratio of potash with other forage minerals, including magnesium and calcium,” he continued.
The EFBA representative also discussed the role of sulphur as a constituent within Irish fertiliser programmes.
“In my opinion, Irish farmers do not include enough sulphur within the fertiliser regimes they follow.
“The ratio of sulphur to nitrogen is critically important in determining both grass output and forage quality.
“Sulphur is a key determinant of protein levels within grasses. The scope to increase the use of this crop nutrient under Irish conditions is significant,” Scott explained.