Earlier this week, Agriland took a trip down to the Solohead dairy research farm to take a hear about the clover trials taking place there.
The farm walk on the Tipperary Co-op and Teagasc Co. Tipperary research farm was organised by Goldcrop.
The farm has been conducting research into clover for the last 20 years.
Dr. James Humphries, the researcher based at Solohead, outlined to the walk attendees the results that have been achieved on the farm using clover and minimal chemical nitrogen (N) input.
Clover trials
Dr. Humphries explained that four trials, with 32 cows/trial, had been taking place on the farm over the last number of years.
On average, the farm get 23 units of N/ha, because over half the farm receives no chemical N.
System Control-High Clover-High Clover-Low Zero-Low Stocking rate (cows/ha) 2.55 2.55 2.55 2.55 Chemical nitrogen input (kg/ha) 250 65 65 0
Trials for 2022
Three trials are being retained and a new trial is being introduced on the farm for 2022:
Control-High: This is a grass system that receives 250kg of chemical N/ha. This trial grew 15.5t of dry matter (DM)/ ha in 2021.
Clover-Low: This system is a clover sward that receives 65kg of chemical N/ha, slurry and lime when required. This trial grew 15t of DM/ha in 2021.
Zero-Low: The Zero-Low system is a clover sward that receives no chemical N, only slurry, compound fertiliser and lime. This trial grew 15.4t of DM/ha in 2021.
New trial: The new trial being introduced this year is a herd stocked at 3.3LU/ha and using red-clover silage from an out block.
Clover
Dr. Humphries explained that the research conducted on the farm has shown that chemical N is not required to grow grass on Irish farms.
The research conducted at Solohead farm shows that white clover with no chemical N, when managed correctly can grow as much grass as a grass sward.
In 2021 the clover trial receiving no chemical N grew 15.4t in 2021, 15.3t in 2022 and 14.9t in 2019.
According to Dr. Humphries, there were no reduced-growth rates experienced in the spring on the clover trials when compared to the swards that received chemical N.
System Control-High Clover-Low Zero-Low GHG (kg CO2e/FPCM) 0.88 0.75 0.69 GHG emmissions (t CO2e/ha) 12.3 10.1 9.5 Ammonia 9kg/ t milk) 4 3.17 2.81
The different plots on the farm are treated the exact same in terms of slurry and lime application.
The results show there is very little difference in milk production and milk solids produced from the trials.
System Control-High Clover-Low Zero-Low Milk (kg/cow) 5,997 6,102 5,687 Solids (kg/cow) 498 506 481 Concentrates (kg/cow) 680 680 680
Based on a 50ha farm milking between 128 and 123 cows, with fertiliser prices based on €1,100/t, the zero-N farm would have a net margin of €1,719 compared to €1,071 for the Control-High farm.
Take-away message
The take-away message from this section of the farm walk was that clover can be used to reduce, or completely eliminate chemical N on farms.
The trials conducted at Solohead have shown there is no reduced growth rates or milk output, but there is a reduction in emissions.
This could go a long way towards alleviating the fertiliser-supply issues currently being experienced on farms and in helping farmers reach emissions targets.
Dr. Patrick Cashmen from Goldcrop added that: “Although this would take a number of years to implement across a entire farm, farmers can look at trialing it in a paddock or two to see how it works on their farm.”
Dr. Cashmen suggested that farmers select a paddock that already has a high-clover content to use as a trial plot on their farm.