Emission Reduction Scenarios

By Colm Kelly, Climate Action & Sustainability Adviser, Teagasc Galway/Clare

Irish Agricultural Green House Gas (GHG) emissions have become part of everyday discussions over the last number of years with higher press coverage and a reduction target of 25% by 2030 getting ever closer. This article will look at two conventional scenarios generated using the assistance of the online Agnav planner tool a collaboration between Teagasc, Bord Bia and ICBF.

What can farmers do?

Niamh is a dairy farmer in Galway who milked 102 cows last year keeping 40 replacement followers and 2 bulls. The total farm GHG emissions estimate was 655 tonnes CO₂ equivalent (eq) which worked out at 10.8 tonnes of CO₂ eq per ha. The farm used 187kgs of chemical Nitrogen/ha of which 57% was urea based and slurry was applied with low emission spreading equipment although mainly in the summer/autumn months.

Table 1: Forecasting difference between a low and high adoption scenario on a dairy farm using Agnav planner

Table 1 shows that had Niamh not already adopted new technologies her emissions would be 3.3% higher last year. If Niamh was able to increase her level of adoption Agnav is able to forecast a further 3.8% reduction in emissions is possible. Strategies to increase the level of NBPT Pro Urea use could be using straight P & K to meet requirements and NBPT Pro Urea + S to meet Nitrogen requirements or using compounds with NBPT Pro Urea as the N source. Conventional 18:6:12 & 10:10:20 are not quantified here although still recommended. In reducing chemical N usage it is crucial that there is no corresponding drop in grass yield which has knock on negative effects on animal performance. To do this is really about replacing chemical N with N from other sources either better use of slurry or quality clover swards. Improving EBI will increase cow performance which can reduce replacement rate and emissions per unit of product.  

Gary is a suckler weanling/store producer in Clare averaging 53 suckler cows, 2 bulls and 51 followers. The farm is estimated to have 263.8 tonnes of CO₂ eq working out at 3.6 tonnes/ha. The farm averaged 66kg N/ha of which 57% was urea based with the rest CAN/compound. All slurry was applied with splash plate but most was applied in spring.

Table 2: Forecasting difference between a low and high adoption scenario on a suckler farm using Agnav planner

Table 2 shows that if Gary was using 100% CAN and was not already targeting slurry ahead of closing for silage that his emissions would be 4.4% higher than today. If Gary got to a full adoption of NBPT Pro Urea and changed from splash plate to Trailing shoe slurry he could potentially drop his emissions a further 2.3%. Further impacts Gary can have that are not captured here is the effect of genetic gain on his farm. Producing weanlings with higher growth rates reduces their eventual age of slaughter which has a positive impact nationally and is a key part of the overall reduction strategy. Niamh can also impact national figures with the quality of beef bull she selects for her dairy cows. Gary is not a high user of chemical N and already times his slurry effectively but he may also extract benefit from quality clover swards to improve weanling performance and lime usage where a soil test identifies a requirement.

Can we get better future reductions?

Feed additives, skill development with clover swards, optimising soil fertility and identifying beneficial genetics are areas where further gains may be made while new diversification opportunities may attract some farmers. Teagasc Signpost Programme is a free service where farmers can sign up online for latest best practice in emissions reduction and to access the Agnav planner. Search Teagasc Signpost signup.

What is the current agricultural emission levels?

The EPA have projected 2023 emissions from Agriculture decreased by 4.6% on 2022. The most significant driver for emissions reduction was a decrease in use of synthetic nitrogen fertiliser (18.0%). Livestock numbers decreased in non-dairy cattle by 1.1%, sheep by 1.2% and pigs by 4.3% while Dairy cow numbers increased by 0.6%.