By Debbie James
Leaving uncut margins in fields of herbal leys has been found to help boost populations of bumblebees and other pollinator insects on Welsh dairy farms.
Six organic milk producers from across Wales who belong to the Narberth-based Calon Wen dairy co-operative have been growing multi species seed mixes, which include flowering herbs, legumes and grasses, for a three-year European Innovation Partnership (EIP) Wales project.
The Pasture for Pollinators Project is examining the impact on pollinator numbers of growing and managing these multi species herbal leys.
Data from the first two years has shown that providing a continuous source of pollen and nectar for pollinators from March to October, and retaining 100 metre uncut strips around the boundaries of these herbal ley fields when they are cut for silage increased numbers of pollinators.
At New Hall Farm, Chirk, where Alan and Heather Rogers milk 190 cows, a survey found that leaving flowering plants uncut increased pollinator numbers; in one section of a field they rose from five to 102, and from 12 to 112 in another.
“Surveys from the other farms in the project showed similar results,’’ says Sinead Lynch, senior conservation officer at the Bumblebee Conservation Trust, a partner organisation with responsibility for the technical and survey work.
The survival of pollinator colonies relies on a continuous food source from March to October but ryegrass, which is widely grown on farms in Wales, doesn’t provide this.
When a field containing clover is cut for silage, pollinators lose a large chunk of their feed source and this happens several times a year when multiple cuts are taken.
Landscapes with a more diverse range of habitats have bigger populations of bumblebees.
Without pollinators, many crops like peas and beans wouldn’t be pollinated to produce the seeds we eat, so farmers involved in the project say it is in the interest of food producers to safeguard the future of these insects.
Each of the six farms is growing two fields of herbal leys and the strip of field left uncut is alternated with every silage harvest – the uncut strip from the first cut is harvested in the second crop and so on.
Lynfa Davies, EIP Wales programme manager, said the project was a good example of a group of farmers who had recognised the wider benefits of pollinators on their farms and who wanted to examine ways of supporting pollinator numbers without impacting on production in their businesses.
“The project offers an opportunity for other farmers to understand how this approach could be applicable to their own systems,’’ she added.
Those involved in the Pasture for Pollinators project hope that the findings could help to influence government policy on future agri-environment schemes.
CASE STUDY
Alan and Heather Rogers have been growing diverse leys for eight years as these species perform well in the dry conditions at New Hall Farm, Chirk.
The farm is in a rain shadow and, as a consequence, rainfall levels are low compared to other regions of Wales.
“The more traditional species that we have been growing, like cocksfoot, are deeper rooting so they perform better than ryegrass in dry conditions, especially on organic systems like ours which don’t apply nitrogen,’’ says Mr Rogers.
These grass varieties also grow earlier in the season which has direct benefits to his spring-calving system.
Mr and Mrs Rogers milk a herd of mostly New Zealand Friesians and Jersey-crosses, producing an annual milk yield per cow of 5,500 litres at 4 per cent butterfat and 3.2 per cent protein.
They already grow diverse species on a quarter of the farm but wanted to get involved in the EIP Wales Pasture for Pollinators project to examine the impact of leaving uncut margins on pollinator populations.
Although herbal leys perform well in their organic system, Mr Rogers says many conventional producers are recognising the benefits of these too because these species draw nutrients from further down in the soil and help improve soil structure; they can also fix nitrogen in the soil, reducing the need for other inputs.
