A technique widely used in Australia and the US could help boost black-grass control. Chloe Palmer finds out more.
Grazing of winter cereals is widely adopted in the southern half of Australia and in the United States but it is rarely seen on arable holdings in the UK. This is despite results of research at home and abroad indicating it has a range of benefits.
The Organic Research Centre (ORC) has undertaken field trials with Suffolk farmer John Pawsey at Shimpling Park Farm near Sudbury to examine this technique to gain a better understanding of how factors such as drilling date, timing of grazing and grazing intensity can influence yield penalties and control of black-grass.
Dominic Amos of ORC believes the results of these trials have been very promising and indicate grazing of winter wheat can provide valuable winter forage for sheep, can play a part in the control of black-grass and if managed correctly, rarely has an adverse impact on crop yield.
Grazing of winter cereals is widespread in New South Wales, Australia. Here, ‘dual purpose’ barley crops are grown so farmers have the flexibility to manage in favour grazing or not, depending on the relative prices for lamb and grain.
However, in contrast to the ORC results, researchers in Australia found later grazing could impact negatively on yield and recommended removing sheep by GS30. Their research confirmed the positive effect of grazing on lodging reduction and they also encouraged earlier sowing dates to ensure there was sufficient forage available for livestock.
Source: NSW Department of Primary Industries, Tamworth
He says: “We did see a small reduction in the amount of tillering in the grazed wheat sown at the usual time but we did not observe any effect on yield. In the early sown crops, we saw no reduction in tillering and there was a significant decrease in the amount of black-grass.
“Our research indicates that for grazing purposes it is desirable to sow the crop early to allow the plants to develop sufficiently to be able to tolerate grazing and to provide enough forage for the sheep flock.”
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The results from the trials also indicated a potential positive effect on lodging.
“Modern wheat varieties are short-strawed and when grown organically do not tend to suffer from lodging. Lodging risk is greater in conventional crops so we think grazing could have an important part to play here.
“We observed crop heights were significantly reduced by grazing and the effects persisted to harvest.
“The application of synthetic nitrogen in the spring to the grazed cereal may promote better recovery of the crop, following grazing, though the added nitrogen may also encourage the black-grass,” Dr Amos adds.
Grazing of winter cereals may have a role to play in wider disease management, according to Dr Amos:
“We think sheep may be able to help by grazing off frost damaged or diseased leaves but we will need to undertake further research to confirm this.
For those looking to try grazing cereals for the first time, Mr Pawsey has some practical advice:
“So far we have only looked at a single variety of winter wheat, Crusoe. It would be useful to look at other cereal crops such as winter barley and other varieties, especially heritage wheats which may fit better in an organic system and due to the taller straw, may be at more of a risk from lodging.”
The Pawsey family has farmed at Shimpling Park Farm for four generations and since 1999, the farm has been organic. Until 2014, the holding was all arable but prior to this, John Pawsey describes how he ‘started thinking creatively’ about integrating sheep into his farming system.
In 2012, Mr Pawsey invited a local shepherd to graze his sheep initially on the farm’s fertility leys to reduce management costs, but then he extended the grazing to his cropped land.
He says: “I had researched grazing of cereal crops and read various articles as well as discussions on forums. I thought I would give it a go so we experimented with grazing 61 hectares (150 acres) of winter wheat in winter 2012.
“The most critical piece of advice I received was to remove the sheep before the wheat reached growth stage 31. We found the grazing did not affect yield but the sheep did graze out some of the weeds.”
Buoyed by this first, largely positive experience, Mr Pawsey decided to repeat the grazing the following winter, and this time he hoped it would tackle an emerging problem in his wheat crop:
“2012 was a terrible year and after all the rain, we found there was a huge amount of septoria in the winter wheat. I thought if the sheep grazed the lower leaves off the wheat, this might prevent the septoria spreading up the plant,” Mr Pawsey explains.
In 2014, Mr Pawsey was approached by the Organic Research Centre to host research trials of grazing winter cereals. The trials have helped to provide him with an insight into what works well and not so well when grazing winter cereals.
“As the weather varies from year to year, it is important to be flexible with the stocking rate adopted because it should be dependent on the conditions at the time,” he says.
When sheep are first grazed on the cereals, he warns the sheep may not start eating immediately because the wheat or barley tastes different to what they are used to. But he says there are no issues with palatability and the sheep soon settle down.
He suggests grazing cereals with sheep is not an exact science and it is difficult to be prescriptive with timing and stocking rates. Nevertheless, he believes the effects of grazing are almost always positive:
“As long as sheep are removed at the right time, there is rarely a negative impact on yield so this ‘opportunistic grazing’ has to be a good thing. For those with their own sheep, it is providing forage at a time when it is usually in short supply elsewhere on the farm.”
Mr Pawsey’s experience with grazing as a tool to control black-grass suggests it could be used as part of the armoury against the weed:
“I believe there is no single solution to the problem of black-grass but I estimate grazing the cereals may reduce it by up to 20 per cent. We use grazing alongside other measures such as spring cropping, choice of variety, drilling date, grass leys and alternating between spring and winter oats.
“Black-grass needs a whole system approach and we try to be completely unpredictable in our cropping to keep one step ahead,” Mr Pawsey adds.
Since 2014, Mr Pawsey has run his own flock of 700 Romney sheep at Shimpling Park Farm and now he intends to increase numbers to 1000 ewes.
“I view the sheep as a tool to help manage our arable land and I am looking to see how both enterprises can benefit each other. We are really excited about what we think the sheep can do for our arable rotation.”
Mr Pawsey undersows all the cereal crops so after harvest, the sheep graze the stubbles to clean them up. This has the benefit of adding nutrients to the arable land and building organic matter.
“I think the benefits sheep bring to an arable rotation apply to any system, not just organic holdings. Where there is a need to take land out of production for a period of time to tackle severe weed infestation, sheep can add fertility and assist with weed control but also provide a source of revenue to ensure the whole rotation generates income.”
At Shimpling Park Farm, grazing livestock on arable land is pivotal to his future rotation as he looks to extend and expand this philosophy.
“We now want to try grazing different crops because so far we have only grazed the sheep on winter wheat. We need to carefully evaluate what is working and what is not and refine our system accordingly.
“We are beginning to think about how we might introduce cattle to the arable rotation but this will require significant investment so it is something for the long term.”