While growing crops is second nature to arable farmers, selecting and growing crops for livestock grazing requires a slightly different approach.
Targeting fields that need improvement, either in terms of soil structure or black-grass control, will aid decision making concerning where and for how long to establish grass leys.
British Grassland Society director, Elaine Jewkes says assuming practical considerations can be met regarding movement of stock, fencing and water supply it is important for farmers to establish what they want from the ley.
“Is it primarily for grazing, or cutting? Do you want to reduce nitrogen fertiliser use by sowing clovers? Herbal leys can be useful, particularly in drier sites.”
Before choosing a seed mix, she advises growers to consider how carefully grazing will be managed. “For example, chicory is a popular addition to sward mixes for its deep-rooting nature, but it needs to be grazed well or it quickly becomes woody and unpalatable.”
Ms Jewkes suggests choosing varieties from the Recommended Grass and Clover Lists. “It’s no different to choosing your arable crop. In drier conditions it may be worth considering a mix with festuloliums as their deep-rooting structure helps to cope with too little - and possibly too much - water. Herbal leys can also be a good option in drier conditions.”
Length of ley affects species selection. “Some crops lend themselves well to different durations – for example, modern red clover will produce well for three, possibly four years; a mix of grass and red clover can therefore fit well into a rotation while providing a productive, high quality silage that can reduce the need for bought-in protein. It can also be a useful ley for finishing lambs.”
Where black-grass is a problem, Neil Groom, technical director at Grainseed, advises a 4-5-year ley. “This gives good seedbank death. Every year you get 60-70 per cent kill of seeds in the ground. So after 4-5 years you will have cleaned the land up.”
Where black-grass is not a problem and silage cuts are planned, a shorter term ley of 18 months is an option to provide a break in the arable rotation and improve soil structure, suggests Mr Groom. “Italian and hybrid rye grasses can be down for 18 months. Italian ryegrass provides more yield in the early years.”
Sowing grass leys is ideally done from March to May or August to early October, says Ms Jewkes. “Sowing clover for autumn reseeds is best done by early September as it may not have chance to establish before temperature and day length fall too much.”
While the traditional method of ploughing and cultivating to give a moderately fine tilth, firmed by rolling, can be effective, where there is no significant compaction there has been a lot of success with direct drilling, says Ms Jewkes.
“There should be as little trash as possible. Herbal leys will tend to require a fine firm tilth.”
It is important not to drill grass seed too deeply, says Mr Groom. “You need to tickle it into the top. You’re not looking to bury it as with cereal seed. Use a ribbed roller such as a Cambridge roller. If you use a flat roller you risk capping. A ribbed roller allows better penetration of water.”
A soil test will reveal whether any nutrient top ups are required, says Ms Jewkes. “There is a separate SNS recommendation for grass – not index 0-4 but high, medium or low. Most land coming out of arable will be low or medium.”
Autumn established grass usually needs no nitrogen, although a small dressing - no more than 30kg N/ha - may be beneficial when direct drilling, as decaying material may slow the mineralisation of organic N. Spring reseeds may need up to 60kg N/ha, she adds.
Potash and phosphorus may be required at establishment; the amounts may be deducted from the P and K needed through the first season. Where grass is being cut for silage, additional P and K may be required, says Mr Groom. “You are removing a lot of P and K every time. If you’re not putting much slurry or digestate back you need to put P and K on as a straight or compound.”
Sulphur is also important - for silage apply up to 40kg SO3/ha per cut, while for grazing apply with N, to a maximum of 125kg SO3/ha per year. In practice moderate N dressing will result in moderate applications of S using an N:S compound fertiliser – most contain 12-15 per cent SO3 and about 27 per cent N, says Ms Jewkes.
While grass leys provide the foundation of any grazing livestock enterprise, there are several forage crops that can be grown for sheep or cattle, offering the opportunity to improve soil structure and fertility and extend the grazing season.
For some arable farmers, growing stubble turnips to be grazed by another farmer’s store lambs, for example, may be as far as they want to go in terms of introducing livestock to an arable rotation.
And for those wanting a relatively cheap, fast growing crop that won’t hold up cereal drilling come spring, stubble turnips and forage rape offer a good option, according to Martin Titley, marketing manager forage crops at Limagrain UK.
“We have seen demand for seed for stubble turnips and forage rape going up but it’s difficult to say whether this is from arable or livestock farmers.”
Stubble turnips and forage rape, which are ideally drilled between mid-July and mid-August, are a good follow-on to winter barley, suggests Mr Titley. “With sowing, the earlier, the better. It is better after winter barley as you can sow earlier. Mid-July to mid-August is perfect but once you are past mid-August daylight hours are disappearing and stubble turnips won’t bulb up quite the same. Instead of tennis balls you’ll end up with ping pong balls.”
Stubble turnips and forage rape are usually drilled directly into stubble and while there will often be enough nitrogen in the ground left from the preceding cereal crop, if the crop looks hungry about 30kg N/ha can be applied, says Mr Titley.
While these forage crops will grow on most soil types, free draining land is better than heavy clay soils otherwise grazing them can prove challenging if conditions turn wet over the winter, says Mr Titley.
Grazing of stubble turnips and forage rape can usually start about 10 weeks after the crop is sown. Stubble turnips cost about £305/ha to grow and forage rape about £408/ha, including seed, cultivation, and inputs, says Mr Titley.
For growers who miss the mid-July to mid-August window for sowing stubble turnips or forage rape, there are still a couple of options, he suggests. “Italian rye grass can be sown into stubble giving a flush of grass for after Christmas grazing. If it is down for 18 months it helps break the cycle of black-grass. It can be sown from mid-August to mid-September. Forage rye can be sown from September through to October for early grazing.”
Of course there are other forage crops such as fodder beet, kale and swede, however, these need to be sown in spring for winter grazing so are more likely to interfere with land availability for growing arable crops unless the grower is prepared to devote land to forage crops for the whole season.