Case Study: Cultivated margins

 

Author: Nicholas Watts
Farm: Vine House Farm, Lincolnshire

Aims:

The aim was to create an insect-rich foraging habitat for farmland birds. I farm on fertile peat soils, so effective control of pernicious weeds is essential.

Management:

I started using this option 5 years ago. For the first four years, I cultivated annually in the spring. Blackgrass is hit by spring cultivations and the seed is short-lived, so successive spring cultivations along with lack of fertiliser have virtually eliminated it.

This year, I applied a herbicide in March to control grass weeds instead of cultivating. This has the advantages of providing seed food for birds through the ‘hungry gap’ (January – April inclusive), providing pollen and nectar throughout the spring, and I think that the plant diversity has increased as a result. It has taken me 4 or 5 years to get the margins to produce food in the lean time of year, because of the need for annual spring cultivations to get on top of the blackgrass. If someone has no blackgrass then an early spring food source can be produced in year two or three. In future, I may only cultivate in alternate years and use herbicide in the 2nd year.

Creeping thistle is a major concern with potatoes and sugar beet in the rotation, so I spot spray thistles with a knapsack sprayer. This has reduced the thistle numbers over time. I had to spot-spray some areas to remove couch and field bindweed with a boom sprayer at harvest time, when the annuals were dormant.

Achievements:

The floristic diversity of these margins is unparalleled by any other habitat on the farm. Plant species richness per margin varies from 55 to 70 species, almost an order of magnitude greater than my wild flower margins, and even more impressive compared with my grass margins, ditch banks and hedgerows.

In years when the spring cultivation is not required, it delivers pollen and nectar throughout the year as well as any sown mixture. Red dead-nettle feeds bumblebees in March and a progression of a wide range of flowers take over from then onwards. When spring cultivation is undertaken, these margins provide pollen and nectar from June onwards.

The full range of farmland birds forage for insects in these margins: grey partridges, linnets, reed buntings, corn buntings and even quail. Turtle doves are scarce on the farm now: common sense suggests that they should use them as a source of seed food too, but I have not been able to witness this. I now have ten times the density of linnets feeding on this farm compared with neighbouring farms. I put this down to the availability of seeds in these margins. I think that the accessibility to the ground in combination with the abundance of insects (and seeds in the case of linnets) provides the ideal conditions for foraging birds.

The combination of spring cultivations, use of selective herbicide and spot-spraying have effectively controlled all of the noxious weed problems. Uncropped cultivated margins are more work than grass margins, but less than some of the other arable options, such as wild bird seed mixtures.

http://www.vinehousefarm.co.uk

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