The little village of Solohead in Tipperary is famous as the place where the War of Independence started over 100 years ago. Solohead has also been home to a dairy research farm since 1976.
The farm is owned by Tipperary Co-Op and is used by Teagasc as a research facility under the control of Moorepark.
The farm was used for clover research from 2000 to 2014 and from 2017 to present. Research on drainage, poaching and fragmented farms took place between 2013 and 2019.
The current project is focused on producing milk with low carbon and ammonia footprints.
James Humphreys and Daniel Barrett at Solohead.
Teagasc researcher James Humphreys explains: “The current project is funded by the Department of Agriculture and its aim is to look at ways to achieve a 50% reduction in greenhouse gas emissions per litre of milk. The national average emissions per litre is currently around 1.2kg CO2eq/l and our target is to produce milk at 0.6kg CO2eq/l.”
James says that on a per hectare basis about 70% of all greenhouse gas emissions are cow-related, with 50% coming from methane from rumen microbes and 20% from nitrous oxide emissions in slurry.
The alternative way to manage methane is a lead bullet but that’s not what we want to see happen
“There may be a solution to methane emissions through the use of feed additives. This would be a silver bullet for methane.
“The alternative way to manage methane is a lead bullet but that’s not what we want to see happen as it will affect milk output. Because the animal factors make up 70% of emissions, we have decided to focus on the remaining 30% of emissions which is mostly related to nitrous oxide emissions from fertiliser,” James says.
There are four treatments in the current experiment. All four treatments are stocked at 2.67 cows/ha overall with the milking platform stocked at 2.95 cows/ha.
The differences between treatments relate to nitrogen usage, clover content, closing farm cover strategy and herd EBI. There are 27 cows on each treatment.
The Solohead research farm is looking at low and zero nitrogen application rates.
The control treatment is a perennial ryegrass sward, with 250kg N/ha being used in conjunction with a high average farm cover at closing. The next treatment is clover with a high closing cover but only 100kg N/ha. The next treatment is clover with 100kg N/ha but a low closing cover, and the final treatment is clover with zero chemical nitrogen and a low closing cover.
Early days
Current research on using clover combined with low nitrogen (100kg N/ha) commenced in Solohead in 2017. The study was adapted in 2019 for the new experiment and a zero-N treatment was introduced. So it’s fair to say that the research on zero N is still in its early days and there would be a significant amount of background nitrogen still in the soil that the grass plant can absorb, even 18 months after chemical nitrogen applications stopped.
If we get 10mm of rain here, the water table rises by 14cm to 16cm
James explains that the heavy soils at Solohead are not prone to nitrate leaching and N loss through the water is very small.
“We have about 20cm of topsoil – 20cm to 40cm heavy subsoil and white marl down at 40cm to 50cm – and the water table is very close to the surface.
“If we get 10mm of rain here, the water table rises by 14cm to 16cm. The nitrate levels in water are very low. The big issue for us is nitrous oxide emissions to the atmosphere after spreading nitrogen.”
In 2017 and 2018, the treatments with 100kg N/ha grew 15.4 and 12.9tDM/ha respectively. This was approximately 1t/ha behind the control treatment at 280kgN/ha, which grew 16.7t/ha in 2017 and 13.8t/ha in 2018. The drought affected the yield for all treatments in 2018. Despite soils being heavier in nature than say Moorepark, drought is still an issue in Solohead and growth rate was even affected by the dry spell this year.
Clover which was oversown in early May coming up in an established sward.
When I visited two weeks ago, farm manager Daniel Barrett explained that the farm was under pressure during the early part of June but the recent rain turned it inside out.
Growth rate since then has been exceptional for all treatments and managing surplus grass in all treatments is the big challenge.
2019 performance
In 2019, the control group produced 497kg MS/cow from 6,072kg milk at 4.60% fat and 3.60% protein. The cows on the zero nitrogen and low closing farm cover produced the exact same level of milk solids at 497kg/cow but from 6,117kg/cow at 4.54% fat and 3.61% protein. Meal fed was the same between both treatments at 460kg/cow but the EBI for zero-N cows was higher at €198 compared to €153/cow for the control group.
James says the reason high-EBI animals were chosen for the zero N treatment was to give this treatment the best chance possible for achieving the desired target of 0.60kg CO2eq/l. In 2019, average grass growth for the zero nitrogen treatment was just 1t/ha behind the control treatment – in other words, it produced 92% of the control treatment. This is despite the fact that no chemical nitrogen was spread on the land area within this treatment.
Of course, this level of performance would not be possible without clover and Solohead is a farm with lots of clover. Secondly, as already mentioned, background nitrogen from previous chemical nitrogen applications is likely to be a contributing factor to pasture growth now. The same response may not be likely in three, five or 10 years’ time, or on very light free-draining soils like those at Moorepark.
Drainage maintenance taking place at Solohead.
The soils at Solohead are very high in organic matter at around 6% on average. This, combined with excellent soil fertility, means that the likely effects of zero nitrogen will take longer to emerge than on other, less fertile soils.
Having said all of that, the 2019 performance is remarkable and what is even more remarkable is that it looks like it will be replicated in 2020. Current and cumulative performance in the different treatments for 2020 is detailed in Table 1.
Cows in the control and two low N treatments have each produced around 250kg MS/cow so far in 2020, while the cows in the zero N treatment have produced 266kg MS/cow.
On cumulative grass growth, the control and two low N treatments have growth around 6tDM/ha, while the zero N treatment is back to 5.43tDM/ha.
“The zero nitrogen treatment is back about 1t/ha on this time last year but that is the same for all treatments as grass growth was relatively poor during late May and June.
At the moment, the zero N treatment is actually recording the highest growth rates so it will be interesting to see how things finish up,” Daniel says.
Closing cover
The control and one of the low nitrogen plus clover treatments operate the standard high closing cover regime of an average farm cover of 700kg/ha on 1 December. The other two treatments, low N and zero N plus clover operate a lower closing farm cover of only 350kg/ha. All herds graze until mid-November but peak and opening average farm cover is obviously much lower in the two low closing cover treatments.
Recently reseeded grass and clover sward at Solohead.
The thinking behind this is that conventional grazing management practices such as building up a high closing cover is not conducive to maintaining clover in the sward. James says that in his experience, clover swards should be grazed bare going into the winter and this will avoid losing cover over the winter.
“The low closing cover is to aid clover stolon survival over the winter, which will increase the amount of clover in the sward and N fixation in the following year.
The challenge is to manage this trade-off: low pasture supply in spring versus higher N fixation during the growing season
Managing the competition between grass and clover is the key to productive clover swards. Shading of clover by grass over the winter can be detrimental to clover survival and productivity in the following growing season. It does not increase pasture growth in spring. In fact, lower pasture supply in spring is the down side of this management tactic.
“The challenge is to manage this trade-off: low pasture supply in spring versus higher N fixation during the growing season. High N fixation is the key to long-term productivity of the system,” James says.
Newly sown grass and clover sward at Solohead.
Slurry is used to drive on pasture growth in spring. Every paddock gets slurry with the trailing shoe using umbilical spreader in late January and again in February/March. A half bag/acre of 0:7:30 is spread on the zero N treatment after every second grazing.
If the level of performance currently being achieved in the zero N treatment is sustained over multiple years, then it is hard to see how the target of producing milk at close to the target of 0.6kg CO2eq/l won’t be achieved. It’s important to state that this could only be achieved in Solohead with exceptional management, particularly around clover. James has been working with clover all his professional life and is passionate about clover.
Other research
Some novel things are being trialled at Solohead. Red clover, hybrid clover and hybrid ryegrasses are all being sown in grazing swards. While the general thinking is that these varieties aren’t suited to intensive grazing systems James says he thinks they are worth investigating as the spring yield benefits, particularly at zero or low nitrogen are too good to ignore. So far, red clover seems to be surviving in the grazing swards. While some of the work on hybrids is still experimental, sowing 10kg perennial ryegrass, 2kg red clover and 2kg white clover has been found to be effective.
Daniel and James have devised a decision support tool to aid decision making around grazing when the weather is wet. A soil moisture probe is used to give readings on the amount of water in the soil. If Daniel is unsure about whether it is too wet to graze he will use the probe to get a reading. Generally, if the water content is above 60% then on/off grazing should be practiced and if it is above 70% then cows should be housed.
Read more
Liquorice Allsorts-style sward for crossbred herd
Dairy Management: chlorine-free wash routines and reseeding
The little village of Solohead in Tipperary is famous as the place where the War of Independence started over 100 years ago. Solohead has also been home to a dairy research farm since 1976.
The farm is owned by Tipperary Co-Op and is used by Teagasc as a research facility under the control of Moorepark.
The farm was used for clover research from 2000 to 2014 and from 2017 to present. Research on drainage, poaching and fragmented farms took place between 2013 and 2019.
The current project is focused on producing milk with low carbon and ammonia footprints.
James Humphreys and Daniel Barrett at Solohead.
Teagasc researcher James Humphreys explains: “The current project is funded by the Department of Agriculture and its aim is to look at ways to achieve a 50% reduction in greenhouse gas emissions per litre of milk. The national average emissions per litre is currently around 1.2kg CO2eq/l and our target is to produce milk at 0.6kg CO2eq/l.”
James says that on a per hectare basis about 70% of all greenhouse gas emissions are cow-related, with 50% coming from methane from rumen microbes and 20% from nitrous oxide emissions in slurry.
The alternative way to manage methane is a lead bullet but that’s not what we want to see happen
“There may be a solution to methane emissions through the use of feed additives. This would be a silver bullet for methane.
“The alternative way to manage methane is a lead bullet but that’s not what we want to see happen as it will affect milk output. Because the animal factors make up 70% of emissions, we have decided to focus on the remaining 30% of emissions which is mostly related to nitrous oxide emissions from fertiliser,” James says.
There are four treatments in the current experiment. All four treatments are stocked at 2.67 cows/ha overall with the milking platform stocked at 2.95 cows/ha.
The differences between treatments relate to nitrogen usage, clover content, closing farm cover strategy and herd EBI. There are 27 cows on each treatment.
The Solohead research farm is looking at low and zero nitrogen application rates.
The control treatment is a perennial ryegrass sward, with 250kg N/ha being used in conjunction with a high average farm cover at closing. The next treatment is clover with a high closing cover but only 100kg N/ha. The next treatment is clover with 100kg N/ha but a low closing cover, and the final treatment is clover with zero chemical nitrogen and a low closing cover.
Early days
Current research on using clover combined with low nitrogen (100kg N/ha) commenced in Solohead in 2017. The study was adapted in 2019 for the new experiment and a zero-N treatment was introduced. So it’s fair to say that the research on zero N is still in its early days and there would be a significant amount of background nitrogen still in the soil that the grass plant can absorb, even 18 months after chemical nitrogen applications stopped.
If we get 10mm of rain here, the water table rises by 14cm to 16cm
James explains that the heavy soils at Solohead are not prone to nitrate leaching and N loss through the water is very small.
“We have about 20cm of topsoil – 20cm to 40cm heavy subsoil and white marl down at 40cm to 50cm – and the water table is very close to the surface.
“If we get 10mm of rain here, the water table rises by 14cm to 16cm. The nitrate levels in water are very low. The big issue for us is nitrous oxide emissions to the atmosphere after spreading nitrogen.”
In 2017 and 2018, the treatments with 100kg N/ha grew 15.4 and 12.9tDM/ha respectively. This was approximately 1t/ha behind the control treatment at 280kgN/ha, which grew 16.7t/ha in 2017 and 13.8t/ha in 2018. The drought affected the yield for all treatments in 2018. Despite soils being heavier in nature than say Moorepark, drought is still an issue in Solohead and growth rate was even affected by the dry spell this year.
Clover which was oversown in early May coming up in an established sward.
When I visited two weeks ago, farm manager Daniel Barrett explained that the farm was under pressure during the early part of June but the recent rain turned it inside out.
Growth rate since then has been exceptional for all treatments and managing surplus grass in all treatments is the big challenge.
2019 performance
In 2019, the control group produced 497kg MS/cow from 6,072kg milk at 4.60% fat and 3.60% protein. The cows on the zero nitrogen and low closing farm cover produced the exact same level of milk solids at 497kg/cow but from 6,117kg/cow at 4.54% fat and 3.61% protein. Meal fed was the same between both treatments at 460kg/cow but the EBI for zero-N cows was higher at €198 compared to €153/cow for the control group.
James says the reason high-EBI animals were chosen for the zero N treatment was to give this treatment the best chance possible for achieving the desired target of 0.60kg CO2eq/l. In 2019, average grass growth for the zero nitrogen treatment was just 1t/ha behind the control treatment – in other words, it produced 92% of the control treatment. This is despite the fact that no chemical nitrogen was spread on the land area within this treatment.
Of course, this level of performance would not be possible without clover and Solohead is a farm with lots of clover. Secondly, as already mentioned, background nitrogen from previous chemical nitrogen applications is likely to be a contributing factor to pasture growth now. The same response may not be likely in three, five or 10 years’ time, or on very light free-draining soils like those at Moorepark.
Drainage maintenance taking place at Solohead.
The soils at Solohead are very high in organic matter at around 6% on average. This, combined with excellent soil fertility, means that the likely effects of zero nitrogen will take longer to emerge than on other, less fertile soils.
Having said all of that, the 2019 performance is remarkable and what is even more remarkable is that it looks like it will be replicated in 2020. Current and cumulative performance in the different treatments for 2020 is detailed in Table 1.
Cows in the control and two low N treatments have each produced around 250kg MS/cow so far in 2020, while the cows in the zero N treatment have produced 266kg MS/cow.
On cumulative grass growth, the control and two low N treatments have growth around 6tDM/ha, while the zero N treatment is back to 5.43tDM/ha.
“The zero nitrogen treatment is back about 1t/ha on this time last year but that is the same for all treatments as grass growth was relatively poor during late May and June.
At the moment, the zero N treatment is actually recording the highest growth rates so it will be interesting to see how things finish up,” Daniel says.
Closing cover
The control and one of the low nitrogen plus clover treatments operate the standard high closing cover regime of an average farm cover of 700kg/ha on 1 December. The other two treatments, low N and zero N plus clover operate a lower closing farm cover of only 350kg/ha. All herds graze until mid-November but peak and opening average farm cover is obviously much lower in the two low closing cover treatments.
Recently reseeded grass and clover sward at Solohead.
The thinking behind this is that conventional grazing management practices such as building up a high closing cover is not conducive to maintaining clover in the sward. James says that in his experience, clover swards should be grazed bare going into the winter and this will avoid losing cover over the winter.
“The low closing cover is to aid clover stolon survival over the winter, which will increase the amount of clover in the sward and N fixation in the following year.
The challenge is to manage this trade-off: low pasture supply in spring versus higher N fixation during the growing season
Managing the competition between grass and clover is the key to productive clover swards. Shading of clover by grass over the winter can be detrimental to clover survival and productivity in the following growing season. It does not increase pasture growth in spring. In fact, lower pasture supply in spring is the down side of this management tactic.
“The challenge is to manage this trade-off: low pasture supply in spring versus higher N fixation during the growing season. High N fixation is the key to long-term productivity of the system,” James says.
Newly sown grass and clover sward at Solohead.
Slurry is used to drive on pasture growth in spring. Every paddock gets slurry with the trailing shoe using umbilical spreader in late January and again in February/March. A half bag/acre of 0:7:30 is spread on the zero N treatment after every second grazing.
If the level of performance currently being achieved in the zero N treatment is sustained over multiple years, then it is hard to see how the target of producing milk at close to the target of 0.6kg CO2eq/l won’t be achieved. It’s important to state that this could only be achieved in Solohead with exceptional management, particularly around clover. James has been working with clover all his professional life and is passionate about clover.
Other research
Some novel things are being trialled at Solohead. Red clover, hybrid clover and hybrid ryegrasses are all being sown in grazing swards. While the general thinking is that these varieties aren’t suited to intensive grazing systems James says he thinks they are worth investigating as the spring yield benefits, particularly at zero or low nitrogen are too good to ignore. So far, red clover seems to be surviving in the grazing swards. While some of the work on hybrids is still experimental, sowing 10kg perennial ryegrass, 2kg red clover and 2kg white clover has been found to be effective.
Daniel and James have devised a decision support tool to aid decision making around grazing when the weather is wet. A soil moisture probe is used to give readings on the amount of water in the soil. If Daniel is unsure about whether it is too wet to graze he will use the probe to get a reading. Generally, if the water content is above 60% then on/off grazing should be practiced and if it is above 70% then cows should be housed.
Read more
Liquorice Allsorts-style sward for crossbred herd
Dairy Management: chlorine-free wash routines and reseeding
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