Cultivated Margins helping arable weeds and Turtle Doves to thrive
By John Secker, Glebe Farm
Glebe farm is an arable farm in West Norfolk, situated on the very western edge of Breckland, growing barley, wheat, oats, sugar beet and beans. Some land is rented out for potatoes and carrots. The soil type is a chalky loam, which gradually becomes lighter and sandier as you go eastwards, until the chalk dips under the free draining sands typical of the Breckland area.
The farm is owned by Chris Cock, and I am the only full time employee. I had worked on the farm for many years, and being interested in natural history and conservation, could see that many species were declining rapidly and some would eventually disappear completely, unless they were given some form of help.
Until 2012, in common with most farms in the area, all of the land was farmed right up to the hedgerows. In February 2012, with help from the RSPB we entered into an environmental stewardship scheme. Options were chosen from both ELS and HLS, which it was thought would benefit the species we already had on the farm. These were Stone Curlew plots, Skylark plots, floristically enhanced grass margins, nectar and pollen plots, wild bird seed plots, hedgerow maintenance, and scrub creation. However the largest area of any option was cultivated margins and plots.
Intensive farming, particularly the use of very efficient herbicides, and applications of artificial fertilisers, has resulted in arable plants becoming one of the fastest declining plant groups.
Cultivated margins are 6 metre strips around the edges of, and sometimes through the middle of fields. They are managed to encourage arable plants to germinate and thrive, by disturbing the soil to create a seedbed suitable for germination of annual ‘weeds’, in the same way as you would prepare for any cereal crop. We find the best preparation is to plough, and then harrow down to a fine, firm seedbed.
Although most of the options were fairly straightforward to implement, the cultivated margins were a particular challenge. There are two ‘windows of opportunity’ to establish the margins. Autumn, in September/October/November, or spring, in February/March. Logic suggests to a farmer that seedbeds should be prepared when the soil is warm and preferably moist. Therefore we opted for early autumn, (September/early October) or late March, to plough and then harrow the margins down to a fine, firm seedbed.
It did not take long to realise that our approach was not working. Although the autumn prepared margins were not too bad, the plants did tend to become very rank and tall. This was not helped by high fertility levels left in the soil by previous crops, and applications of artificial fertilizer to those crops. Early cultivation resulted in some Sterile Brome and Cleaver issues. The margins prepared in the spring were not at all what a farmer likes to see! They were dominated by Fat Hen, which was about a metre high, annual mercury, and ‘weed beet’. All of these plants can be a particular problem in crops grown on the farm, and so we did not want to encourage their proliferation.
Experience soon taught us that preparing the margins earlier in spring, or later in autumn, when the weather was cooler, and the soil temperature lower, overcame all of these problems almost entirely. The ‘problem’ weeds all seeming to prefer warm conditions to germinate. Autumn preparation is now carried out in late October/early November, and spring preparation as early as possible in February. Fat Hen is still common, but nowhere near as dominating as before. It is a desirable species as a source of seed for birds, but particularly as a food plant for the Brush-thighed Seed-eater beetle, a nationally rare ground beetle which can be found in Breckland.
The Breckland area is well known for its unique suite of rare and uncommon plants, which occur as a result of the relatively hot dry summers and cold winters, geographical position, and light sandy soils.
The margins now have a wide range of annual plants (about 100 species have been recorded) and are full of colour from early April, when Speedwell and Fumitory species turn them blue, purple and white, through the summer, when there is a magnificent show of red Poppies and yellow Charlock, and into autumn when they are white with Mayweed.
Of particular interest are Night-Flowering Catchfly, Rough Poppy, Prickly Poppy, Fine-leaved Fumitory, Dense-flowered Fumitory, Dwarf Spurge, Venus’s Looking Glass, and Flixweed. Dense Silky Bent, a rare grass, has also been found. Big populations of most of these species have built up now, despite being rarely seen prior to entering into a stewardship scheme.
The richness of plants in these margins also benefits many invertebrates. Bumble bees, solitary bees, butterflies and moths have all become noticeably more common around fields where there are cultivated margins. Grey Carpet Moth, a red data book species whose foodplant is Flixweed, and is a Breckland speciality, is common wherever the plant grows on the margins.
It is a privilege to walk through a margin with such a diverse range of plant species, and see the insects which are making use of them to collect pollen and nectar, and use them as food plants.
Many bird species also feed in the margins and plots. Large flocks of grey Linnet feed on the seeds provided by the many species of plant. Corn Bunting, Yellowhammer, Reed Bunting, Chaffinch, Goldfinch, Brambling and Skylark are all common throughout winter and early spring.
However the species that has undoubtedly benefitted the most is the Turtle Dove. A very common species on the farm until the 1970’s, but as with the rest of the UK, a catastrophic decline in numbers resulted in no sightings at all for many years.
One of the main reasons for this decline in numbers is thought to be a lack of seed availability when the birds arrive back from Africa in spring. In about 2015 we decided to try supplementary feeding to hopefully bridge that ‘hungry gap’, until more natural seed becomes available. A mix of red and white millet, oilseed rape and canary seed was scattered along a track running beside a large area of scrub on the edge of the farm, at about the time that Turtle Doves arrived back from their long migration. The seed is topped up as and when required, but never allowed to build up. It did not take long before one or two birds were seen on the food, and numbers increased steadily over the next few years.
As the season progresses, seed becomes available in the cultivated margins, and birds are seen feeding in them almost every day. We have a mix of autumn and spring prepared margins right across the farm, and also cooperate with a neighbouring farm to try to ensure seed is becoming available right through the season. This is particularly important as we think that Turtle Doves prefer seed which is ‘milky ripe’, rather than fully ripe and therefore dry. They often appear to target a particular margin for a week or so and then move on to another one. Turtle Doves feed exclusively on small seeds, and one of their favourites is fumitory, which is very common on margins right across the farm. Over the years numbers have increased and we now have more than 10 pairs benefitting from supplementary feed and cultivated margins here and on neighbouring farms. However, just providing food alone is not sufficient to encourage Turtle Doves. They also require areas of scrub, or tall, wide hedgerows for nesting, and preferably a source of drinking water nearby.
To be able to visit the site on a fine summers evening to hear several Turtle Doves calling together, and watch them displaying over their nest sites is a joy I had thought I would never experience again. We have been very pleased to host evening farm walks for other local farmers, and hopefully they too will be encouraged to try to help make the turtle dove a common sight in our farmed landscape once again.
John and Chris at Glebe Farm are members of the Breckland Farmers Wildlife Network (BFWN), a farm cluster with 58 members and growing. They allow the network to hold evenings on their exemplary cultivated margins where farmers can learn from John’s experience, and hear from other wildlife experts at Natural England, Plantlife and Operation Turtle Dove. This inspires others to improve their management which encourages a wider range of priority species and turtle doves, which are seen during the evening.