Teagasc publish reports to inform Nitrates Action Programme and Derogation

This is in line with commitments made in Water and Agriculture – a Collaborative Approach as part of the ongoing work in preparing Ireland’s next Nitrates Action Programme and importantly securing a continuance of Ireland’s Nitrates Derogation.

The reports, which will be published on www.teagasc.ie are:

• Environmental and economic modelling of the impact of adjustments in the maximum stocking rates permitted under Ireland’s Nitrates Derogation
• Slurry and dairy soiled water volume estimates – Final Data Summary
• Improving slurry nutrient distribution on dairy farm holdings
• An environmental and economic assessment on the impact of possible reductions in the maximum chemical nitrogen allowances for all grassland stocking rates
• An environmental and economic assessment on the impact of possible reductions in the maximum chemical nitrogen allowances for main arable crops

 

The report on ‘Environmental and economic modelling of the impact of adjustments in the maximum stocking rates permitted under Ireland’s Nitrates Derogation’ estimated that approximately 49% of dairy farms in Ireland and 65% of national milk production was produced on farms that had an organic nitrogen (N) stocking rate of greater 170 kg/ha.  If these 7,609 farms were required to reduce organic N stocking rate to 170 kg/ha, this would require an average reduction of 27 cows/herd and result in a reduction (on average) of €43,555 (39%) in family farm income on those farms, if this was achieved by reducing cow numbers only. This would result nationally in a reduction of 203,719 cows (14%) and a reduction in national milk production of 1.2 billion litres (15%). The report also evaluated the impact on farm income of other compliance strategies such as i) renting additional land, ii) exporting slurry from dairy farms and iii) contract rearing dairy heifer replacements plus non-replacement livestock.  These strategies led to reductions in family farm income of €10,928 (15%), €18,841 (19%) and €11,136 (14%) respectively on the farms affected.

The report on ‘Slurry and dairy soiled water volume estimates’ found that on dairy farms the volume of slurry and soiled water produced is underestimated presently compared to the current regulations which require 0.33 m³/cow/week for slurry storage and 0.21 m³/cow/week for soiled water storage, plus an allowance for rainfall runoff from any adjacent uncovered area. This outcome reflects higher milk yields and more slurry output, necessitating more capacity than previously mandated by outdated benchmarks. This report will provide guidance to DAFM to inform policy associated with any potential changes to current regulations. Farmers will face significant costs to provide additional storage capacity should these higher rates be adopted and must plan ahead for investments, possibly using the Nutrient Storage Investment Scheme (TAMS 3).

The report on ‘Improving slurry nutrient distribution on dairy farm holdings’ emphasises that significant opportunities exist to improve nutrient use efficiency through better slurry management. Since a proportion of organic N is captured when cows are housed, redistributing this slurry away from milking platforms and onto support lands can help balance nutrient loads depending on stocking rates. A methodology was developed in this report with varying milking platform stocking rates to examine the different proportions of the slurry to be distributed to the area that was not available for grazing for the milking herd, based on the organic N excretion rate of the herd and the chemical N application rate per hectare. Where the overall maximum chemical N allowances is 214 kg/ha, 25%, 50%, 75% and 100% of the slurry would be distributed for herds in Band 2 at milking platform stocking rates 3.3, 3.5, 3.6 and ≥3.9 cows/ha. No slurry is required to be distributed at stocking rates of less than ≤3.1 for herds in Band 2. Compared to herds in Band 2, herds in Band 1 can operate at a higher platform stocking rate for a similar percentage of slurry distributed, while herds in Band 3 would have to operate at a lower platform stocking rate.  Optimising slurry distribution will allow farmers to reduce reliance on chemical fertilizers, improve grassland productivity, and minimise nutrient loss to the environment.

The report on ‘An environmental and economic assessment on the impact of possible reductions in the maximum chemical nitrogen allowances for all grassland stocking rates.’ indicates that pasture-based farms have reached a critical point in terms of chemical N fertilizer application rates. Irish agriculture has significantly reduced the use of chemical N fertiliser in recent years. Further reductions in the maximum allowable chemical N applications on grassland risk exacerbating feed deficits on farms, pushing dairy production systems into deeper reliance on external feed sources. Improving soil fertility, increasing the efficiency of organic manures, and incorporating white clover into perennial ryegrass swards are effective strategies for reducing the reliance on chemical N fertilizers. However, these technologies need greater adoption at farm level before further reductions in chemical N allowances are possible.

The report on ‘An environmental and economic assessment on the impact of possible reductions in the maximum chemical nitrogen allowances for main arable crops’ outlined that the current fertiliser levels used are based on an economic optimum, above which further yield increases do not cover the cost of the additional fertilizer, they are therefore, below the rate to achieve maximum yield. Research also shows that the residual nitrate-N at harvest of a crop remains relatively stable until applications exceed N optimum and then increase steadily as additional fertilizer N is applied.  Reducing recommended N rates for arable crops is therefore unlikely to provide any environmental benefit but risks reduced yield and profitability in a farming system. Arable systems are at risk of N leaching in the autumn and winter due to the mineralization of organic N residues when there is no crop to take up the N. Establishment and maintenance of over winter green cover is therefore the key action in arable systems to reduce the risk of over winter N leaching. 

Conclusion

The risk of not being able to renew the nitrates derogation will significantly undermine the profitability and viability of pasture-based ruminant livestock system.  While progress has been made in reducing chemical N use and adopting sustainable practices, abrupt further reductions in maximum allowances on grassland and arable crops without adequate transition pathways would have severe consequences for grass production and grain yield and would undermine farm incomes, milk and grain production. On dairy farms the volume of slurry and soiled water produced is underestimated presently due to improvements in milk yields over time, highlighting the need for additional slurry storage on farms.   Optimizing slurry distribution will allow farmers to reduce reliance on chemical fertilizers, improve grassland productivity, and minimise nutrient loss to the environment.

For more information on the reports, please click on these links:

1. 1. Environmental and economic modelling of the impact of adjustments in the maximum stocking rates permitted under Ireland’s Nitrates Derogation
   2. Improving slurry nutrient distribution on dairy farm holdings
   3. An environmental and economic assessment on the impact of possible reductions in the maximum chemical nitrogen allowances for all grassland stocking rates
   4. An environmental and economic assessment on the impact of possible reductions in the maximum chemical nitrogen allowances for main arable crops
   5. Slurry and dairy soiled water volume estimates – Final data summary