Preparing for the summer grass growth window a wise investment
24 February 2023
Making the right decisions to improve business resilience is key and industry experts agree that producing the best quality silage possible is an important first step towards achieving this.
Paul Macer, of Kite Consulting, says after a difficult grass growing season in 2022, characterised by periods of prolonged and severe drought across much of the country, many farmers have ‘nothing to fall back on’ in the way of forage stocks.
He says: “There are two main concerns at the forefront of many dairy farmers’ minds.
Firstly, they are thinking about how best to get to ‘grass day’ with current forage stocks.
"Secondly, the ‘cupboard will be bare’ at the start of the season, so how can they make enough silage to have plenty for next winter plus a buffer moving forward?”
Mr Macer says farmers should consider how they are going to take advantage of the ‘tremendous window for grass growth’ in May and June, because those who did not do this in 2022 are now ‘really struggling’.
Those who significantly cut back on fertiliser in the early season last year lost out on significant yield at a time when grass growth was excellent.
Even with the price of fertiliser where it is, it is still a wise investment because, ultimately, silage is still by far the cheapest feed, especially when compared to concentrates which are markedly more expensive now.
“I am a keen advocate of multi-cut, because it is a sure way of making the best quality forage to fill the clamp in terms of energy and the protein content.
“It is important for farmers to ‘get out of the traps early’ and aim for shorter cutting intervals to allow an extra one or possibly two cuts over the growing season.
“Keeping grass swards young and productive pays dividends, but it is also about looking after soil and addressing any issues, such as compaction, which could compromise grass growth.
With a changing climate, everything is about managing risk so consider ways to ensure there is always some silage left at the back of the clamp.
Utilising nutrients as efficiently as possible is central to controlling costs, Mr Macer says, and testing soil and slurry so fertiliser and manure can be targeted where it is needed most is a good starting point.
“Look carefully at your soil analysis results and explore the different options before you purchase a fertiliser so that what you apply is the best match for any nutrient deficiencies.
“Applying lime where lower than optimum pHs are identified is the best investment you can make to improve yield.
Look carefully at your soil analysis results and explore the different options before you purchase a fertiliser - Paul Macer
“It is worth remembering sulphur is now deficient in most areas of the country. Numerous experiments have shown that balancing it results in higher yields and better true protein values in forages.
Even though grass is costing more to grow and harvest, making the best of home-grown forage is still the bedrock of a cow friendly, competitively priced ration.
The hot summer of 2022 shone a spotlight on older grass swards, as newer leys with a higher proportion of fresh, productive ryegrasses performed better and kept growing, even as drought conditions began to bite.
Older leys lose vigour over time and weed grasses begin to make up a higher proportion of the sward, says John Spence, forage crops product manager with Limagrain UK.
“In older swards, species such as less productive meadow-grasses begin to dominate,” he says.
“They are problematic because they have a short growth cycle so head quickly and are also prolific seed producers.”
Meadow-grasses are very shallow rooting, so burn off more easily in the dry weather. Newer ryegrass varieties and clovers are deep rooting and are better placed to withstand drought conditions,” Mr Spence explains.
In a typical five-year-old ley, containing 80% ryegrass, losses in energy value can be as much as 33,200MJ per year, Mr Spence says.
Replacing this amount of energy in the diet with a cereal-based concentrate would cost over £900 based on current bought-in feed costs.
With a typical full cultivation reseed costing around £850, this really demonstrates the false economy behind ‘making do’ with old swards.”
Choosing grass mix
When choosing a grass mixture, Mr Spence advises farmers to consider what they want from the ley and how long they want it to last.
If the mixture is to be shortterm, so one to two years, Italian ryegrasses are the best choice, with the inclusion of hybrid ryegrasses if forage quality is a priority.
“For medium-term leys of three to four years, a mixture of hybrid ryegrasses and perennial ryegrasses is recommended.
Where the ley is expected to last over four years, mixtures dominated by perennial ryegrasses work best.
"Think about the primary purpose of the ley; if it is to be predominantly used for silage with some aftermath grazing, choose a mixture formulated for cutting.
The true dual purpose mixtures will have intermediate heading and later heading perennial ryegrass varieties which stay leafy for longer and perform well when grazed.
Recommended lists are a useful guide, but Mr Spence says the information needs to be interpreted with care.
“The varieties on the recommended lists are the best ones available, but farmers should be discerning with their choices.
There can be up to 20% difference in yield between those varieties at the top and the bottom of the tables.
“The varieties on this list are tested under different management regimes, so look at where each variety performs best.
Some grass varieties are best suited to cutting, others are more suitable for grazing.
“Look at performance across the whole season; the lists are based on trials run during spring and summer.
Limagrain runs its own research trials across the whole growing season, which provide a better picture of how mixtures will perform in the field.
The best mixtures will contain a range of grass varieties which complement each other. Testing the performance of individual varieties in trials is important, but it is also advantageous to evaluate the mix as a whole to see how the attributes of each species perform together,” Mr Spence adds.
Farmers should look at the feed value of the different varieties too when selecting mixtures, including energy, digestible fibre and protein, rather than only referring to yield, Mr Spence says.
Philip Cosgrave, grassland agronomist with Yara, suggests the likelihood of drought and other weather extremes occurring more frequently needs to be factored into how farmers grow grass and other forage crops.
“Farmers will need to produce more silage than they previously thought necessary as a means of insuring themselves against periods of lower forage production.
Those on a more conventional three cut silage system may need to consider switching to a four or five cut system to maximise grass production and regrowth, especially earlier in season.
If switching, it is important to be aware of higher machinery and labour costs, but also feeding higher quality silage means higher dry matter intakes which could increase silage requirements.
“Silage analysis results are pointing to lower protein content this year and part of the reason for this is possibly the lower rates of nitrogen applied to silage crops in 2022 due to high fertiliser prices.
Applying 20 to 40 percent less nitrogen is likely to equate to a reduction of between two and three percent protein.
“The best way of maintaining good protein levels in silage regardless of cutting frequency is to apply optimal rates of nitrogen and sulphur.
Generally, the greater the cutting frequency, the higher the silage protein is likely to be, from early May onwards, grass protein decreases nearly 2% every week, on first cuts.
“Soil analysis is essential to identify any deficiencies and nutrient management planning should always guide fertiliser applications, particularly with regard to how they are balanced with organic manures.
Sulphur should not be sacrificed as it is probably delivering 10% higher silage yields. There is not enough available sulphur in slurry to meet the needs of a first or second cut silage. 90% of grass silages made in the UK are deficient in selenium. Using a fertiliser which is fortified with selenium is an easy and cost effective way of increasing the levels in silage by two to three percent,” Mr Cosgrave says.
If slurry is applied straight after harvest, applying fertiliser a week afterwards will aid the regrowth of the sward and reduce nitrous oxide emissions from applied nitrogen.
If just fertiliser is being applied then this should be applied immediately after harvest. “Applying an ammonium nitrate-based fertiliser will consistently deliver higher silage yields than urea. Furthermore, nitrogen loses through ammonia volatilisation are known to be 10 times greater for urea when compared to ammonium nitrate, which is a real concern as the industry seeks to lower ammonia emissions,” Mr Cosgrave adds.
He urges farmers not to simply compare the headline prices of different fertiliser products, but rather to examine what form the fertiliser is in and how well it can be applied.
“A true uniform product will have granules containing each of the composite minerals. For blended products, each granule comprises a different mineral so when spreading, it is rather like putting golf balls and table tennis balls in a spreader and trying to apply them evenly.
“The greater the width of the spreader, the harder it is to achieve an even spread.”
To avoid frustrating and costly delays at mowing time, Craig Bryson, Krone territory sales manager, urges farmers to make best use of the quieter winter months so everything is ready to go when the time comes to mow.
He says: “Do not leave it until the day before you plan to mow to carry out your maintenance checks as it will be too late to source parts and carry out repairs.
Check the blades and conditioning tines on the mower and make sure they are set up correctly for the weather and ground conditions at the time.
“If the necessary time or expertise is not available on farm, consider taking machines down to your nearest dealership over the winter to do the necessary checks and servicing.
“They can look to see whether there has been any excess or uneven wear on any of the parts which might suggest incorrect set-up.
Making the necessary set-up adjustments will reduce the wear and tear on the machine and can also save fuel because the machine is not running too heavily along the ground and dragging,” Mr Bryson says.
When making decisions about buying a new machine, Mr Bryson suggests farmers should be thinking of the longer term and investing in a high quality machine which will last.
“If it is practical for the farm, consider purchasing bigger machines as these will require fewer passes across the field, reducing compaction and the likelihood of travelling over cut grass. This should also mean the machine will last longer,” Mr Bryson says.
He adds that in the UK, farmers tend to mow much closer to the ground, leaving a very short stubble for regrowth. He says this is in contrast to farmers in Europe, who tend to leave 10cm to 12cm behind.
“Cutting higher up the plant means the grass will grow back more quickly – you need grass to grow grass. Furthermore, the quality of the grass going into the clamp will be better and what you sacrifice in volume you will gain in quality.
“Chop length is also an important consideration in relation to rumen health as if the grass going into the clamp is very short, it will go through the rumen more quickly. This can mean it is necessary to supplement the diet with straw or another source of fibre,” Mr Bryson adds.
Timeliness, in terms of cutting and wilting, together with achieving the right pH in the clamp, are key to the production of high quality silage.
This is according to Peter Smith, silage expert at Volac, who urges farmers to try and cut as early as possible to make the most of the early part of the growing season.
“For the past few seasons, farmers who cut in April and managed to secure a second cut before the end of May have ended up with more silage of a higher quality in the clamp.
Those who were not able to complete the first cut until mid-May, because they missed the early dry weather, often found the grass had become too strong.
Consequently, sugar and protein content was reduced and the grass did not recover as well after mowing,” Mr Smith says.
More farmers are switching to a multi-cut system and are learning to do it better, Mr Smith says, and are therefore avoiding many of these common pitfalls.
“With multi-cut silage, it is important to wilt the grass properly to avoid problems with clamp slippage. Care needs to be taken not to over roll or stack too high in the clamp if the crop is below the target dry matter.
“When making multi-cut, the aim should be between 30 - 35% dry matter [DM], with 32 percent being the target. Even at 35% DM, the grass should compact well as it is leafier.
Wilting as quickly as possible is key; ideally the grass should be mown in the morning and tedded out immediately. If weather conditions are right, it should be possible to pick it up on the same day, which will give less opportunity for respiration losses in the crop.
“About 20% of sugars in grass can be lost within 24 hours, so the sooner the grass can be wilted down to the optimum DM and placed in the clamp, the higher quality the silage.
Even if cut grass has to be left overnight, if it is already quite dry, there will be less opportunity for dew to condense,” Mr Smith says.
Mr Smith highlights the importance of reducing the pH of silage quickly.
The aim must be to drop the pH rapidly to inhibit the undesirable bacteria from turning the grass sugars into unpalatable acids and other waste products which will result in high DM losses.
Typical losses in an untreated clamp will be around 10%. “Applying one million Lactobacillus plantarum (MTD/1) bacteria per gram of grass in an additive such as Ecosyl drives a rapid and efficient fermentation process, resulting in a swift drop in pH and minimal DM and sugar losses.”
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