According to the researchers the next step in proving the value of clover and getting it adapted widely is to roll the clover system out on to commercial farms, and study the results.
These pastures will be tested on a range of soil types and management systems, and the results compared with those achieved in Clonakilty and Moorepark, and on a number of commercial farms.
I am confident the results will be good because, for many decades, I have been in close contact with farmers who strongly believe in clover.
The massive results from Teagasc trials to date will surely convince the doubters.
A good opportunity to lay down some clover swards is just after cutting a good crop of first cut silage. A proven method of introducing clover into existing clean ryegrass pastures is broadcasting 2kg of clover seed per acre into bare clean stubbles after first cut silage.
This method has been developed and perfected on the Teagasc Solohead farm in Tipperary.
If possible use a light coat of slurry, but don’t disturb the soil surface as this will only cause weeds to germinate.
Don’t apply nitrogen, and graz tightly until the clover is established. The biggest threat to success is drought.
These clover pastures have been proved to support over two cows per hectare yielding over 1,400 gallons each on moderate levels of concentrates and only 72 units of N per acre (including silage).
Where a more normal level clover pasture is required, 1kg of clover seed and some tetraploid ryegrass per acre could be used, especially if the stubble is clean and thinned out a little.
Despite our fairly suitable climate for clover, it has not played a very important role in Irish farming. In general Irish farmers don’t appreciate the potential of clover to increase the profitability of their farming systems.
This is mainly due to the relatively low price of N fertilisers until the 1990s, and neglect of clover systems research until the late ’90s.
Indeed, some researchers and advisers used to regard clover as a nuisance.
Some farmers abandoned clover because of its lack of persistency but modern management can overcome most of this problem.
Management is a little different from management of pure grass pastures, but not necessarily more difficult.
It is amazing that farmers are taking so long to adapt to clover pastures, when their many advantages have been proved for decades.
In the ’90s, researcher James Humphries and colleagues established high level clover pastures on the Solohead research farm in Tipperary by the method described above. Their system of laying down clover swards has been successfully adapted on some commercial farms.
Trials have been carried out in Moorepark comparing ryegrass pastures receiving 150 kg of N or 250 kg of N/ha, with similar ryegrass-clover pastures receiving the same N.
The clover significantly increased milk solids production, by 85kg and 96kg per ha. Trials by researcher Brian McCarthy and colleagues at Clonakilty Agricultural College show similar increases from clover in milk solids, and an increase of 2t of grass DM production. Grazing cows on pastures with 30% clover in Clonakilty resulted in an extra profit per cow of €160.
Moorepark researchers say clover can contribute to the sustainability of grass based systems. The Solohead clover pastures produced 33% less nitrous oxide emissions and 16% less total greenhouse gas emissions compared with non-clover systems. Nitrogen fixation rates (free N from the air) of up to 170 kg per ha per year have been measured in grass-clover swards at Moorepark and Solohead.
Proper use of clover can significantly cut the cost of N fertiliser and provide a superior type pasture.
Following the results of all the trials to date, it is time for Irish farmers to trust clover and use it more widely, and to include about 1.5 kg of clover seed when reseeding.
Perhaps grazing rotations could be lengthened a little when clover is plentiful, because clover does not lose digestibility as quickly as grass, and more mature clover, plus grazing techniques, can be used to reduce the risk of bloat.
Cows should not be let into wet lush clover pastures too hungry; or a break wire could be used to limit their intake in the first few hours. Over the years, researchers have learned it is not good practice to keep switching cows from clover-rich pastures to grass pastures.
It is possible to switch the entire grazing platform into clover pasture over four years, even with only 10% reseeding.
Clover can be top seeded or stitched into well-grazed, clean pastures, in the spring.Even where 250 kg of N/ha is applied, up to 40 kg of extra milk solids per cow can be expected from clover pastures, with good management. Stitching clover into poor pastures with weeds and poor grass is not worthwhile.
Clover, like grass, is very sensitive to soil fertility; P and K and lime must be right, to gain the full benefit of clover pastures.