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A lack of rain during the second half of May, and for much of June, has slowed the establishment of clover across both dairy and beef paddocks at Greenmount.
Addressing a seminar at the National Sheep Association (NSA) open day at Tynan Abbey on Tuesday, CAFRE technologist Robert Patterson said the aim was to establish grass clover swards across the entire cattle grazing platform at Greenmount over the next four years.
He acknowledged a four-year timeframe was not realistic for most farmers, given the need to take out 25% of the grazing area each spring, but CAFRE wanted to “fast-track” the process to see if it is possible to hold grass yield while cutting annual nitrogen (N) input by 100kg/ha.
Timing
According to Patterson, the optimal timing to establish clover is from mid-April to the end of May. Paddocks should be at a pH of around 6.5, with phosphorus (P) and potassium (K) indexes at 2+ to 3.
A number of techniques are being trialled to establish clover, including into swards that have been baled, tightly grazed or pre-mowed before grazing.
Some of the paddocks have been over-seeded, with 2.5kg of clover per acre using either an Einbock seeder, an Erth drill fitted with discs or a similar Aitchison drill developed in New Zealand.
A control simply had clover incorporated into slurry as it was applied to a paddock.
Alternative
The alternative to over-seeding is a full reseed, and this has involved burning off the existing sward, discing and power-harrowing to create a tilth, and sowing with 12kg of perennial ryegrass and 2kg of white clover per acre.
In all cases, granular lime was applied, along with P and K, where required.
The benefit of over-seeding is that it involves less disturbance of soil, so is less likely to encourage weeds.
There is also a three- to four-week turnaround, meaning less of a production hit when compared with a full reseed, when the sward is normally out for eight to 10 weeks.
However, conditions were not ideal this spring, and it will be 12 to 13 weeks before cattle are grazing the full reseed.
“Only in the past couple of weeks have we seen it come through,” said Patterson.
Over-sowing paddocks with clover was done between 8 May and 23 May.
Those early in the period got off to a good start. The clover disappeared during subsequent dry weather, but “it is coming in really strongly now,” said Patterson.
Those fields done later in the period got off to a bad start, but the clover has started to germinate in the last couple of weeks, he added.
This includes the control, where clover was added to slurry. The initial assessment is that there is less clover coming through, so it would need to be repeated multiple times.
No N was applied at sowing or after the first grazing in new swards, and after that it will be applied at a half rate (12.5kg N/ha).
It is important not to let grass out-compete the clover (cattle will go into swards at 2,600t to 2,800t dry matter/ha) and to graze out as tightly as possible.
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