Lots of factors impact on the quality of maize and grass silage. Olivia Cooper caught up with an award-winning silage maker.
Good forage is the foundation of a healthy, productive herd, but quality can be notoriously variable. However, with a little attention to detail, it is possible to make excellent silage year in, year out, as one award-winning farmer has discovered.
Graham Duke, who farms with his wife Jill and son Lloyd near Launceston, Cornwall, won this year’s maize silage category in Mole Valley Farmers’ Forage for Profit awards. Launched in 2009 to help farmers improve the quality of their grass and silage, the awards recognise excellence in all categories of forage.
The average UK dairy farm is only getting about 2,000 litres of milk from forage, and that figure is falling, according to Graham Ragg, arable and fertiliser sales manager at Mole Valley Farmers.
“In 2009, we analysed 3,000 samples of grass silage, and the average Metabolisable Energy was just 10.3MJ/kg, which was a bit of a shock – that is only marginally above the cows’ maintenance level.” Average dry matter was 33%, with protein at 13.6%.
But since then, with the help of MVF expertise, farmers’ samples have improved markedly, to average 36.7% dry matter, 11.1MJ ME, and 14.3% protein, boosting intake potentials by 7%.
“The better the silage is, the more of it the cows will eat,” says Mr Ragg. Farmers have made similar progress with maize silage, boosting dry matter from 27% to 31%, protein from 8% to 8.4%, and starch from 24% to 30.8%.
“Mr Ragg puts th improvements down to farmers cutting their grass silage a couple of weeks earlier, and holding off maize harvest until the crop is really ready.
“They are also choosing early varieties, which is helping – 75% of the seed we sell is now for early varieties. Many are also drilling at lower seed rates of 103,000 seeds/ha (42,000/acre). This means you get more sunlight between the plants, and bigger cobs, which is where all the starch is.”
Mr Duke has always worked hard to make good-quality silage, but about 18 months ago he installed two milking robots at South Bridgetown Farm, and now houses the 140 cows year-round during their lactation, making him more dependent on the forage he makes.
The farm runs to 130ha (320 acres), of which 16ha (40 acres) is sown to maize, 12ha (30 acres) to wheat for crimping, and 12ha (30 acres) to spring barley. The rest is temporary silage leys, with some permanent pasture that is grazed by young stock and dry cows.
Two years ago the family took on a tenancy at Buttern Farm, five miles away, which runs to a similar acreage but with 170 cows that are milked through a herringbone parlour and graze day and night during the summer months. All of Bridgetown Farm’s bull calves and beef calves are finished on the farm, whereas Buttern Farm operates as a flying herd, with all the females put to a British Blue bull and calves sold for finishing elsewhere.
At Bridgetown Farm, the Holstein/Friesian cows have responded well to the robotic milking, with yields increasing from 8,500 litres to 9,500 litres and rising. “I don’t know how much is attributable to the robot and how much to the forage,” says Mr Duke. Yields from forage average 4,000 litres, with butterfat at 4.1% and protein at 3.3%. At Buttern Farm, yields are lower at 6,800 litres, with 3,000 from forage, and butterfat and protein averaging 4.3% and 3.5%, respectively.
Since Mr Duke took on the tenancy at Bridgetown Farm eight years ago, he has reseeded a lot of the grassland and brought some into an arable rotation. As a result, he is taking four cuts of grass silage, with a total yield of 57t/ha (23t/acre) – about 25% more than he would have achieved before reseeding. First-cut silage averages 12.1-12.3MJ ME, with an average across all cuts of 11.3MJ, a target of 30% dry matter and 15% crude protein.
To keep on top of winter growth, he grazes all the pasture with sheep from October to January. “In a mild winter, we get a lot of growth – but in a frost it goes yellow and almost rots. If you don’t take that off, it ends up in your silage.” He applies 100kg/ha (80 units/acre) of nitrogen fertiliser, plus 5,000 gallons/ha (2,000 gallons/acre) of slurry after each cut, with grazing land receiving about 38kg/ha (30 units/acre) every 23 days.
“We normally cut our first crop in the first week in May, then every six weeks afterwards, depending on the season. The final cut is usually at the end of September, and we are aiming for consistent results.”
With the help of a contractor, he chops the grass at about 2in long, applies an inoculant and rolls the clamp continuously before wrapping it as quickly as possible. “It’s important to get the air out quickly.”
The maize is usually sown into fresh ground to reduce the disease and weed pressure, at a rate of 99,000 seeds/ha (40,000/acre). “We used to try and get a first cut of grass silage before sowing maize, but it gets too late and you lose its potential.” After maize, Mr Duke sows wheat, followed by a two- to three-year grass ley on good maize ground, or a longer six-year ley on other land.
Having grown 21 different varieties for MVF trials, he is confident of choosing the right variety for his land.”
Preparing land for silage making
Mr Duke pays great attention to his soil, testing it every year for nutrient levels. “We are on good soil, with pH 7, which is ideal for release of nutrients.” Phosphorus and Potassium indices are usually at two to three, due to the large amounts of available slurry, with about 12,350 gallons/ha (5000 gallons/acre) applied at an estimated 20.13.80 analysis. “We split the slurry spreading in two – with some in February/March and most just before ploughing. If I could, I would spread it all just before ploughing.”
After ploughing he power harrows and sometimes subsoils the fields. “We like to get a good deep seedbed, but drill as soon as we can after ploughing so it doesn’t dry out.” He applies 370kg/ha (150kg/acre) of 16.0.30 to the seedbed before drilling, followed by 120kg/ha (50kg/acre) of 18-46-0 DAP at sowing.
The crop also receives a pre-emergence herbicide, but rarely needs much more than that. “We try to avoid post-emergence herbicides because they can knock the crop back. Because we mostly grow on fresh maize ground, there is less need for sprays.” He checks for crop dry matter before harvest, and then ensiles the maize in a clamp separate from the grass.
Milking cows are fed 2kg of haylage at 40% dry matter, 10kg of maize, 5kg of wholecrop barley, 22kg of grass silage, 1kg of molasses, and 4kg of blend, with concentrates fed to yield in the robotic milker. “We tend to feed one cut of silage at a time, and we sample the face every month so we can balance the ration accordingly. The quality can change dramatically over the winter, and if you believe you’re feeding 11.5 ME and it’s actually 10.5, you have a real problem,” says Mr Duke.
At Bridgetown Farm the cows, which calve year-round, are milking themselves 2.6 times a day on average, with high yielders up to four times a day. “They are peaking about seven litres higher than they were, and are generally milking a lot flatter as well.”
Top tips for maize silage
• Sow into a deep seedbed and analyse the soil regularly
• Choose an early variety with high starch yield
• Reduce seed rate to 103,000/ha (42,000/acre)
• Wait until the crop is fully mature before harvesting
• Compress and wrap the clamp quickly to eliminate air
• Analyse the clamp face regularly to balance the ration