Preliminary results from a two-year Teagasc survey on soiled water and slurry requirement on farms show that actual amounts of both accumulated exceed that of current legislation.
As it stands, farms must have slurry capacity of 0.33m³/cow/week (330 litres) across the closed period for their area, while soiled water storage requirements for dairy farms stands at 0.21m³ (210 litres) week for a minimum of 31 days, bar those with a liquid milk contract who have up to 2025 to establish this storage.
Regarding slurry, from November to February (peak months), the average volume collected was 413.8 litres/cow/week, which includes rainfall runoff amounting to the equivalent of approximately 20 to 40 litres/cow/week on average.
Figure 1. Average litres per cow per week collected in slurry tanks for each month in the period from July 2023 to June 2024 (all sources included)
The contribution from rainfall runoff varied between farms and week by week. This marks a 30% increase over current volumes when using the average collected.
For soiled water production, the average volume collected in peak months (July to October and March to June) was 300 litres/cow/week, which includes rainfall runoff amounting to the equivalent of approximately 20 to 40 litres/cow/week on average.
Figure 2. Average litres per cow per week collected in soiled water tanks for each month in the period from July 2023 to June 2024 (all sources included)
Again, the contribution from rainfall runoff varies between farms and week by week. Taking this average volume collected, a 42% increase in the storage volume is required.
For tanks collecting both slurry and soiled water, the peak volume collected was in October at 626.7 litres/cow/week.
Figure 3. Average litres per cow per week collected in combined slurry and soiled water tanks for each month in the period from July 2023 to June 2024 (all sources included)
Total volumes collected include rainfall runoff amounting to the equivalent of approximately 20 to 40 litres/cow/ week on average.
Preliminary results only
The current slurry volumes used to quantify the volume of slurry a dairy cow produces have been in place since the nitrates directive was implemented in Ireland in 2006, despite an increase in the productivity of the typical dairy cow in Ireland.
The preliminary data from year one of this study "suggests that the volume of slurry produced by a cow is underestimated currently, as is the soiled water produced on farm," according to the study.
The study also noted that significant volumes of water is getting into storage tanks on farms, amounting to the equivalent of approximately 20 to 40l/cow/week on average.
The study was completed between July 2023 and June 2024, an exceptional period regarding rainfall for the majority of the country. The year one results notes that a second year of monitoring is required to provide a full understanding of overall volumes collected and that the data presented is "preliminary in nature and should not be interpreted as the final outcome of this work".
It also notes that "while this project will provide data to DAFM to inform policy associated with the nitrates action programme, any changes to current regulations will be dependent on the consideration of a range of associated issues by DAFM, in addition to this data".
Tank sampling
As well as the focus on the volumes collected, a sampling campaign was undertaken to estimate nutrient content of slurry/soiled water on a selection of the study farms.
Preliminary results from a two-year Teagasc survey on soiled water and slurry requirement on farms show that actual amounts of both accumulated exceed that of current legislation.
As it stands, farms must have slurry capacity of 0.33m³/cow/week (330 litres) across the closed period for their area, while soiled water storage requirements for dairy farms stands at 0.21m³ (210 litres) week for a minimum of 31 days, bar those with a liquid milk contract who have up to 2025 to establish this storage.
Regarding slurry, from November to February (peak months), the average volume collected was 413.8 litres/cow/week, which includes rainfall runoff amounting to the equivalent of approximately 20 to 40 litres/cow/week on average.
Figure 1. Average litres per cow per week collected in slurry tanks for each month in the period from July 2023 to June 2024 (all sources included)
The contribution from rainfall runoff varied between farms and week by week. This marks a 30% increase over current volumes when using the average collected.
For soiled water production, the average volume collected in peak months (July to October and March to June) was 300 litres/cow/week, which includes rainfall runoff amounting to the equivalent of approximately 20 to 40 litres/cow/week on average.
Figure 2. Average litres per cow per week collected in soiled water tanks for each month in the period from July 2023 to June 2024 (all sources included)
Again, the contribution from rainfall runoff varies between farms and week by week. Taking this average volume collected, a 42% increase in the storage volume is required.
For tanks collecting both slurry and soiled water, the peak volume collected was in October at 626.7 litres/cow/week.
Figure 3. Average litres per cow per week collected in combined slurry and soiled water tanks for each month in the period from July 2023 to June 2024 (all sources included)
Total volumes collected include rainfall runoff amounting to the equivalent of approximately 20 to 40 litres/cow/ week on average.
Preliminary results only
The current slurry volumes used to quantify the volume of slurry a dairy cow produces have been in place since the nitrates directive was implemented in Ireland in 2006, despite an increase in the productivity of the typical dairy cow in Ireland.
The preliminary data from year one of this study "suggests that the volume of slurry produced by a cow is underestimated currently, as is the soiled water produced on farm," according to the study.
The study also noted that significant volumes of water is getting into storage tanks on farms, amounting to the equivalent of approximately 20 to 40l/cow/week on average.
The study was completed between July 2023 and June 2024, an exceptional period regarding rainfall for the majority of the country. The year one results notes that a second year of monitoring is required to provide a full understanding of overall volumes collected and that the data presented is "preliminary in nature and should not be interpreted as the final outcome of this work".
It also notes that "while this project will provide data to DAFM to inform policy associated with the nitrates action programme, any changes to current regulations will be dependent on the consideration of a range of associated issues by DAFM, in addition to this data".
Tank sampling
As well as the focus on the volumes collected, a sampling campaign was undertaken to estimate nutrient content of slurry/soiled water on a selection of the study farms.
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