Rob Hodgkins and Jo Franklin in stubble turnips

Sheep grazing is proving to be a shot in the arm for arable growers in north Hertfordshire grappling with blackgrass and thin soils by boosting soil fertility and spring barley yields.

A two-year-old sheep enterprise is now offering growers of stubble turnips and cover crops nutritional and soil benefits without the chore of daily shepherding.

Jo Franklin started growing mustard cover crops in 2010 to raise soil organic matter on her arable land and then grazing them off with the four-legged beasts to drive up yields of subsequent crops.

The light arable soils she farms between Baldock and Royston benefit from the winter grazing to produce an extra 0.5t/ha of spring malting barley sold last harvest for £150/t.

“We are drilling cover crops at a seed cost of £30/ha to get a benefit of £75/ha for the following malting barley crop,” she tells Farmers Weekly.

The mustard crop is also having a role in controlling blackgrass, helping to smother the grassweed and show some allelopathic effects, whereby the mustard exudes substances to inhibit blackgrass.

Mustard crop

She manages 1,000ha of arable land with her father Philip from Lower Heath Farm, and in a separate business she helps run a 1,100-strong sheep flock with her partner Rob Hodgkins.

The sheep enterprise rents 200ha of permanent grassland from 13 landlords for summer grazing, while the stock is overwintered on stubble turnips and cover crops grown by surrounding arable farms.

“The future for livestock in this area is huge with the current blackgrass issue and the thin soils, and something has got to change with wheat prices around £100/t,” Mr Hodgkins says.

One neighbouring farm is growing 28ha of stubble turnips and three others, including Lower Heath Farm, are growing 200ha of cover crops for potential use by the sheep.

See also: Harvest 2015 figures reveal 18-year high for barley

Mr Hodgkins pays for the cost of the stubble turnips in terms of seed and fertiliser, and the neighbour gains from the fertility added by the sheep, which are controlled using electric fencing.

He argues that the sheep graze down the blackgrass in the winter, and the resultant blackgrass is more easily killed by glyphosate when it is smaller and strongly growing in the spring.

There is no shortage of neighbouring farmers looking to offer permanent pasture and also grow over-wintered cover crops so rapid expansion is in their plans.

“We would aim to get to 2,000-2,500 ewes within five years,” he says. Currently, there are 800 breeding ewes and 300 ewe lambs set to enter the breeding flock.

On the arable Lower Heath Farm, four miles south-west of Royston, work with blackgrass control using stale seed-beds resulted in extremely disappointing weed control, and Ms Franklin has seen better control from using the mustard cover crops.

This season she drilled a 8ha cover crop trial at the end of August with a number of different mixtures to compare with the farm’s standard mustard crop, sown at 14kg/ha which has been used for the last five years.

This mustard crop has impressed Ms Franklin as it has improved soil structure, organic matter, crop nutrition and blackgrass control, and every year the area has been expanded.

This year 120ha of mustard cover crops are being grown, and the beneficial effects of the sheep grazing them off has boosted yields of spring malting barley Propino.

The yield of this spring-sown crop was boosted by 0.5t/ha to 8t/ha last summer and all reached a malting specification of 1.45% grain nitrogen and was sold at £150/t.

The rotation on the light land farm is based around winter wheat, oilseed rape and spring barley.

Over on the sheep side, the New Zealand Romney breed was chosen as it was bred as a forage-based low-maintenance sheep ideal for a low-cost sheep unit.

On the Hertfordshire unit, the sheep are fed no concentrates, no worm drenching is needed for the ewes as they are moved between permanent grassland and cover crops, and all the lambs are finished on grass, stubble turnips and cover crops.

The use of grass leys on the arable farm was rejected as being too expensive to justify for the sheep enterprise, compared with using permanent grass from parkland, hillsides and small pockets at more economical rents.

Lambing starts relatively late for a lowland flock in early April when there is plenty of grass, and a slightly low lambing percentage of 178% is ideal as Mr Hodgkins does not want any triplet lambs.

If the lambing percentage was closer to more traditional lowland levels of 200%, or two lambs per ewe, then the bigger chance of triplets which would mean more labour.

Lambs are weaned at 100 days and sold between mid-September and Christmas, and sold on average for £60 a lamb with a production cost of £42-45 a lamb.

Running 1,100 sheep on 200ha of grassland is certainly not heavy stocking but Mr Hodgkins explains much of the grassland is in environmental schemes where no nitrogen fertiliser is allowed.

Ms Franklin is one of four AHDB monitor farmers based in the eastern region of England, which are aimed at creating a focus to bring together like-minded farmers who wish to develop or expand their enterprises by sharing critical performance data.