Digging the dirt on soil compaction and outwintering – Report from demo farm open meeting in Cornwall.

Digging the dirt on soil compaction and outwintering – Report from demo farm open meeting in Cornwall.

Friday, September 19, 2014

On Tuesday 16th September over 60 farmers gathered at Trink Dairy near St Ives for a DairyCo-BGS demo farm open meeting, kindly hosted by Chris and Rachel Knowles.

Trink is an exceptional farm; located in the south-western tip of the British Isles it benefits from a mild and maritime climate; used to great advantage in the extended grazing system embraced by the Knowles in response to the low milk prises of the late 1990’s. The freely draining, light soils, underlain with solid granite bedrock are also sympathetic to outwintering; and by adopting a system that uses these environmental positives as a spring-broad to maximise the use of grazed grass the Knowles have been able to keep input costs low and optimise profitability.

Nevertheless, their involvement with the demonstration farm partnership is underlined by the acknowledgement that in even the most forgiving environmental settings, good management practice is critical.

Compaction

One of the take home messages from the day was that even light soil can get compacted. Over recent years surface slitting has become an annual task at Trink to remedy surface compaction cause by general livestock trampling.

Researchers at SRUC and HAU are currently investigating the impact of cattle trampling and tractor compaction on soil structural damage and grass yield. In 2011 researchers imposed three treatments on a permanent grassland sward: cattle trampling, tractor and no compaction.

They have found that both tractor and cattle compaction increased soil bulk density and that water retention was increased by 17%. The effects of compaction led to reduced first cut grass yields by approximately 20%.

Event speaker, independent consultant Chris Duller, revealed visibly increased root growth into and around the slits in the test plot where the knife style aerator had been used this spring.

One of the aims of the demo farm partnership going forward is to undertake a cost-benefit analysis looking at the influence of aeration techniques on soil structural parameters, yield and sward composition. “We are comparing two types of slitting treatments in both spring and autumn operations” explained Charlotte Evans from BGS.

Outwintering

Participants were bussed out to a group of small granite hedged fields that the Knowles use for outwintering. If it had been a clearer day they would have been able to see the sea on three sides, with the iconic St Michaels Mount out in the bay to the east, and the so called ‘golden mile’ of fertile daffodil producing land to the west of the mount sweeping away below them. As it happened the murkiness of the weather only served to focus attention further on the discussion of management practices that allow successful outwintering, led by Norton Atkins from HAU.

Heifers are currently outwintered at Trink on grass with silage bales and infrequent supplementary cake. They are rejuvenated in the spring with partial cultivation and box-seeder and participants could see the positive effect of doing this in terms of repairing fields to be used again the following year.

Research conducted at HAU surveyed 70 farmers who outwinter heifers finding the top reasons for doing so were:

  1. To reduce the cost of heifer rearing
  2. To improve animal health and welfare
  3. To reduce labour input
  4. To alleviate pressure on buildings.

Choosing free-draining, dry soils was the primary criteria for selecting a suitable area to out-winter heifers and assisted in avoiding poaching and run-off and providing dry lying areas.

The first winter of our demonstration will be 2014/15. It will consider choosing the site and stocking rate; supplementary feeding decisions and repair and reseeding decisions.

For more information from our demo farms project visit our Demo Farms page

 

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