Topless cubicles became common during the dairy boom of 2015-2019, with many areas replacing outdoor woodchip pads.
It was seen as a solid middle-of-the-road option between pads and a fully roofed cubicle shed – with the potential in the future to roof over and create the latter option once cow numbers increased and milk started flowing into the bulk tank.
Topless cubicles are a bit like marmite: you either love them or hate them, and it’s the same for cows.
On a fine, mild autumn or spring day, the majority of cows will opt for the outdoor cubicles. However, on a wet, cold or snowy day/night, the topless cubicles will be vacant and cows will emigrate indoors wherever possible.
On those mild, warm days, cows will opt for outdoors as they are better able to regulate their body temperature, but in reality, the best option for winter is a well-ventilated, roofed cubicle shed, as there is simply no protection from wind-driven rain or snow with topless cubicles.
Another issue topless cubicles create is the volume of water they collect. The average rainfall amount across the island of Ireland is between 750-1,000mm in the western half, with those in the eastern half typically seeing rainfall amounts of 1,000-1,400mm.
This level of rainfall entering slurry tanks is a major cause of concern for two reasons: it increases the volume of slurry produced and at the same time reduces the utilisable space within tanks.
How much space does water take up?
This will be very much dependent on where in the country you are living, with a variance of 650mm or more in rainfall levels.
To calculate approximately how much water you are talking about, we need to know the volume of the tank. A standard 10-bay (4.8m bays) long outdoor tank with a 14ft 6in slat on top of it to give an internal width of 4.3m and an internal depth of 2.4m will have a gross capacity of 495.4m³.
If we are to take this tank and place it in Tipperary, the mean annual rainfall there for the closed period (October to mid-January) is 330mm. Combined with this, we have to have a 300mm freeboard available, which is 100mm more than for covered tanks.
Finally, we will be unable to remove all of the slurry from the bottom of the tank (unless a sump is in place), so there will be approximately 100mm of slurry left at the bottom. The breakdown of our tank is as follows then:
Freeboard – 300mm (12.5%).Rainfall – 330mm (13.75%).Slurry – 1,670mm (70.25%).Slurry at bottom – 100mm (4%).The result being that, in reality, we are only utilising 70% of tank capacity. While the slurry level may rise in to the freeboard, this will more than likely be a result of wet weather, with the double whammy being that rainfall will fill the tank, while making land less trafficable to spread.
The cost of spreading this water also needs to be taken in to account. While watery slurry is useful for spreading with LESS equipment, there is still a cost to the excess water collected.
Taking Tipperary again as an example, the long-term average annual rainfall is 935mm. With all this entering the above 10-bay tank, we are accumulating 192.98m³ of water that will have to be spread, be it of use or not.
This, in old money terms, comes to 42,000 gallons. Spreading at a rate of three 2,000 gallons tankers/hour at €100/hour, it’s costing €700 annually to spread water.
While this volume of rainfall might be useful to dilute down thick beef slurry, dairy slurry by its nature needs less dilution, and there is usually an abundance of soiled water on-farm anyway to mix with it.
If the above farmer found themselves tight on slurry storage, there are two options they can go for: roof over existing storage or create more storage. But which makes the most sense?
Open yard will only give a utilisable slurry storage area of approximately 70%, depending on the rainfall amount in your area.\ Odhran Ducie
Option one: roof over tank
Roofing over the tank will eliminate the rainfall element, so from the closed period we regain the 330mm of space taken up by rainfall.
As well as this, for cross-compliance purposes, we can also reduce our freeboard space to 200mm as the area is now roofed, meaning in total we have gained 430mm of our tank depth back. In m², this equates to 88.75m², or just under 19,500 gallons.
Cost will depend on a number of factors; whether pads will have to be poured for upright stanchions, or if grafting on to existing stanchions on an older shed is an option. As a rough guide, a price per m² for the above will be in the region of €110-€130/m².
With an overall area of approximately 216m², we are looking at a cost of €25,920+ VAT. The above assumes that the frame and roof will be installed, with no concrete or barriers included.
On a cost per m² of slurry storage gained, the above is working out at €292/m², which is definitely on the high side.
Option two: more slurry storage
If we were to forego a roof and just build another mass concrete tank, what would the cost be there? Around 19,500 gallons is a relatively small tank, so a mass concrete tank would really be the best option.
However, as we have displayed above, we are only really getting 70% utilisation from an open slatted tank. To be able to comfortably store 19,500 gallons, we would have to create 28,000 gallons of slurry storage. 28,000 gallons is the equivalent of 127.3m². Taking our tank width and depth to be the same as above (4.3m and 2.4m respectively), our tank would have to be 12.36m in length, roughly 2.5 standard bays.
Smaller tanks will be on the upper end of price compared to larger ones, so a price guide of €140/m² would be likely, giving a total cost of €17,822 + VAT. You may question as to why, when the cost per m² is less than half of that of roofing that the price is more than half, but as shown, with 30% of the space of the tank not being utilisable, our cost per utilisable cubic metre is higher than the tank cost.
It’s not as black and white as just looking at €10k plus of a difference in price. For the roofing option, if done right, cows will eat less due to lower energy demand to keep themselves warm. In the case of the new tank, unless we join the new and old tanks together, then we will have to pump slurry from the old to the new tank.
If we do join them, there will be an additional cost of construction, while if we are to use these as an animal area and cover with slats, install barriers, etc, we could expect to spend an additional €5,000 plus.
We also need to factor in the cost of spreading water, as mentioned above. €700 per annum doesn’t sound like much, but over a 10-year period, it will have the balance of the roofing paid off.
If, given the above scenario, my preference would most likely be to roof the area, especially in a high rainfall area. Once done right, there is a welfare benefit to animals with having a roof over there heads, while there is less slurry created on-farm which should be a reduced environmental risk.
Financially, while the new tank seems the cheaper option, when all variables are calculated, it likely will be the more costly in the long run.
In short:
Open tanks or topless cubicles collect huge volumes of water each year.Open tanks only have a utilisable area of 70% of their capacity when all is taken in to account.Roofing an open tank will cost in the region of €110-€130/m². Storage space created from roofing will cost €290/m².Creating a new standalone tank will cost approximately €140/m², however, other factors such as slats, barriers, pumping slurry need to be taken in to account here.
Having stanchions in place for roofing in the future is common place in many topless scenarios and will reduce the cost of roofing and construction.
Topless cubicles became common during the dairy boom of 2015-2019, with many areas replacing outdoor woodchip pads.
It was seen as a solid middle-of-the-road option between pads and a fully roofed cubicle shed – with the potential in the future to roof over and create the latter option once cow numbers increased and milk started flowing into the bulk tank.
Topless cubicles are a bit like marmite: you either love them or hate them, and it’s the same for cows.
On a fine, mild autumn or spring day, the majority of cows will opt for the outdoor cubicles. However, on a wet, cold or snowy day/night, the topless cubicles will be vacant and cows will emigrate indoors wherever possible.
On those mild, warm days, cows will opt for outdoors as they are better able to regulate their body temperature, but in reality, the best option for winter is a well-ventilated, roofed cubicle shed, as there is simply no protection from wind-driven rain or snow with topless cubicles.
Another issue topless cubicles create is the volume of water they collect. The average rainfall amount across the island of Ireland is between 750-1,000mm in the western half, with those in the eastern half typically seeing rainfall amounts of 1,000-1,400mm.
This level of rainfall entering slurry tanks is a major cause of concern for two reasons: it increases the volume of slurry produced and at the same time reduces the utilisable space within tanks.
How much space does water take up?
This will be very much dependent on where in the country you are living, with a variance of 650mm or more in rainfall levels.
To calculate approximately how much water you are talking about, we need to know the volume of the tank. A standard 10-bay (4.8m bays) long outdoor tank with a 14ft 6in slat on top of it to give an internal width of 4.3m and an internal depth of 2.4m will have a gross capacity of 495.4m³.
If we are to take this tank and place it in Tipperary, the mean annual rainfall there for the closed period (October to mid-January) is 330mm. Combined with this, we have to have a 300mm freeboard available, which is 100mm more than for covered tanks.
Finally, we will be unable to remove all of the slurry from the bottom of the tank (unless a sump is in place), so there will be approximately 100mm of slurry left at the bottom. The breakdown of our tank is as follows then:
Freeboard – 300mm (12.5%).Rainfall – 330mm (13.75%).Slurry – 1,670mm (70.25%).Slurry at bottom – 100mm (4%).The result being that, in reality, we are only utilising 70% of tank capacity. While the slurry level may rise in to the freeboard, this will more than likely be a result of wet weather, with the double whammy being that rainfall will fill the tank, while making land less trafficable to spread.
The cost of spreading this water also needs to be taken in to account. While watery slurry is useful for spreading with LESS equipment, there is still a cost to the excess water collected.
Taking Tipperary again as an example, the long-term average annual rainfall is 935mm. With all this entering the above 10-bay tank, we are accumulating 192.98m³ of water that will have to be spread, be it of use or not.
This, in old money terms, comes to 42,000 gallons. Spreading at a rate of three 2,000 gallons tankers/hour at €100/hour, it’s costing €700 annually to spread water.
While this volume of rainfall might be useful to dilute down thick beef slurry, dairy slurry by its nature needs less dilution, and there is usually an abundance of soiled water on-farm anyway to mix with it.
If the above farmer found themselves tight on slurry storage, there are two options they can go for: roof over existing storage or create more storage. But which makes the most sense?
Open yard will only give a utilisable slurry storage area of approximately 70%, depending on the rainfall amount in your area.\ Odhran Ducie
Option one: roof over tank
Roofing over the tank will eliminate the rainfall element, so from the closed period we regain the 330mm of space taken up by rainfall.
As well as this, for cross-compliance purposes, we can also reduce our freeboard space to 200mm as the area is now roofed, meaning in total we have gained 430mm of our tank depth back. In m², this equates to 88.75m², or just under 19,500 gallons.
Cost will depend on a number of factors; whether pads will have to be poured for upright stanchions, or if grafting on to existing stanchions on an older shed is an option. As a rough guide, a price per m² for the above will be in the region of €110-€130/m².
With an overall area of approximately 216m², we are looking at a cost of €25,920+ VAT. The above assumes that the frame and roof will be installed, with no concrete or barriers included.
On a cost per m² of slurry storage gained, the above is working out at €292/m², which is definitely on the high side.
Option two: more slurry storage
If we were to forego a roof and just build another mass concrete tank, what would the cost be there? Around 19,500 gallons is a relatively small tank, so a mass concrete tank would really be the best option.
However, as we have displayed above, we are only really getting 70% utilisation from an open slatted tank. To be able to comfortably store 19,500 gallons, we would have to create 28,000 gallons of slurry storage. 28,000 gallons is the equivalent of 127.3m². Taking our tank width and depth to be the same as above (4.3m and 2.4m respectively), our tank would have to be 12.36m in length, roughly 2.5 standard bays.
Smaller tanks will be on the upper end of price compared to larger ones, so a price guide of €140/m² would be likely, giving a total cost of €17,822 + VAT. You may question as to why, when the cost per m² is less than half of that of roofing that the price is more than half, but as shown, with 30% of the space of the tank not being utilisable, our cost per utilisable cubic metre is higher than the tank cost.
It’s not as black and white as just looking at €10k plus of a difference in price. For the roofing option, if done right, cows will eat less due to lower energy demand to keep themselves warm. In the case of the new tank, unless we join the new and old tanks together, then we will have to pump slurry from the old to the new tank.
If we do join them, there will be an additional cost of construction, while if we are to use these as an animal area and cover with slats, install barriers, etc, we could expect to spend an additional €5,000 plus.
We also need to factor in the cost of spreading water, as mentioned above. €700 per annum doesn’t sound like much, but over a 10-year period, it will have the balance of the roofing paid off.
If, given the above scenario, my preference would most likely be to roof the area, especially in a high rainfall area. Once done right, there is a welfare benefit to animals with having a roof over there heads, while there is less slurry created on-farm which should be a reduced environmental risk.
Financially, while the new tank seems the cheaper option, when all variables are calculated, it likely will be the more costly in the long run.
In short:
Open tanks or topless cubicles collect huge volumes of water each year.Open tanks only have a utilisable area of 70% of their capacity when all is taken in to account.Roofing an open tank will cost in the region of €110-€130/m². Storage space created from roofing will cost €290/m².Creating a new standalone tank will cost approximately €140/m², however, other factors such as slats, barriers, pumping slurry need to be taken in to account here.
Having stanchions in place for roofing in the future is common place in many topless scenarios and will reduce the cost of roofing and construction.
SHARING OPTIONS