New grassland research examining the performance of foliar nitrogen
There has been a great deal of interest over the last three years in foliar applied nitrogen (N) on grassland. To learn more about the performance of foliar N on grass, Yara UK began a replicated plot trial in 2023 which will run for three years.
The trial is modelled on a 4-cut silage system, with the first cut taking place in early May, with subsequent cuts taken every 5 weeks approximately.
The total season N rate per ha for the 5 treatments (trt) is as follows: trt 1 - 0 kg, trt 2 - 340 kg (100% soil applied), trt 3 - 203 kg (86% soil applied, 14% as a slow-release foliar N product), trt 4 - 203 kg (100% soil applied), trt 5 - 203 kg (28% soil applied, 72% as a foliar urea product + humic acid). The total N application rate for trt’s 3, 4 and 5 is 40% lower than trt 2.
The foliar N is applied 10 – 12 days after the previous cut to ensure there was enough leaf surface to intercept the foliar products.
2024 results - The total dry matter (DM) yield per ha for each trt was 4,490 kg, 12,371 kg, 10,285 kg, 10,536 kg and 8,985 kg for trt 1, 2, 3, 4 and 5 respectively. The N response for trt 2 and 5 was 23 and 22 kg/DM per kg of applied N, while trt 3 and 4 had a N response of 29 and 30 kg/DM per kg of applied N respectively.
More information on this research can be found on our website.
Spreading nitrogen and sulphur at the same time means more grass
Applying fertilisers containing nitrogen and sulphur means the grass uses nitrogen more effectively, you get more kgs of dry matter per kg of nitrogen that you apply
Welsh beef farmer is crowned BGS Grassland Farmer of the Year
Dylan and Wyn Jones, from Castellior, Menai Bridge, Anglesey, were announced as the winners of the British Grassland Society Grassland Farmer of the Year competition for 2024. The announcement was made at an Awards Dinner jointly hosted by BGS and the East of Scotland Grassland Society at The Park Hotel, Peebles on Wednesday 23 October. The competition and the Awards Evening are kindly sponsored by Yara, Germinal, and Nufarm.
Dylan and his father Wyn, who are members of Anglesey Grassland Society, farm just over 330 ha and finish 1,500 beef steers per year. Mainly Holstein, with some dairy crosses are bought in at 16 – 24 months of age weighing 420 – 480 kg. Around 100 – 150 of the cattle are weighed weekly and are sold when daily live weight gain (DLWG) falls towards 1.0 kg. The finishing period is 92 – 140 days with an average DLWG of 1.7 kg/day. They are sold at 630 – 680 kg with carcass weights of 310 – 380 kg.
The farm is self-sufficient with barley and peas grown on the farm. These are crimped and fed to cattle along with silage made from red clover, and Westerwolds in a multi-cut system. A typical rotation on the farm is winter barley, spring barley, followed by two-to-three-year leys.
The competition is always hotly contested, and this year was no exception. The judging panel commented that all the farms were at the top their game and were worthy of being in the final three. The runners-up were Philip and David Clarke from Fermanagh Grassland Club and Peter Done from Cheshire Grassland Society. You can read more about these three farms here.
Soil fertility is vital: Test It, Review It & Take Action
At some stage over the next couple of months plan to do some soil testing if you haven’t done so already. Once you have the results don’t file them in a drawer! Review them and use them to put together a nutrient management plan (NMP) for 2025. Your NMP is about prioritising how to use organic and mineral nutrients on the farm in the most cost-effective way possible.
Too often organic manures are applied on the same parts of the farm, year after year. There are plenty of reasons why this is done, but it’s not maximising the potential value of this valuable resource. Using umbilical spreading systems may be an option to target other areas of the farm. Target cattle slurry at low K index soils as it’s a cost-effective potash source.
Intensively stocked grassland farms should consider soil testing more regularly. By soil testing every 2 – 3 years you’re in a better position to monitor soil fertility trends. Fertiliser recommendations are not an exact science, hence soil testing more frequently together with measuring grass yields will help you fine tune your NMP for every paddock or field on your farm.
Remember, leys require a continuous and balanced nutrient supply from the soil to achieve its production potential. If a farmer is regularly soil-testing, say every three years, then the €1 ha/year cost is money well spent.
For more information on soil testing this spring search online for “Yara analytical services”
Have you noticed the decline in Grassland P & K Fertility?
The latest 2023 British survey of fertiliser practice published in July does not paint a good picture for the state of grassland soil fertility in Britain. The overall P & K application rates on grassland, and the percentage area of grassland that receives a fertiliser dressing of P & K has not recovered since 2022, which is a concerning national trend. Only 22% and 24% of grassland receives P and K respectively, down from 37% and 39% in 2021.
On those fields that receive P and K, there was a 1 kg increase in field P rates on both grazing and silage from last year and an increase in K of 2 kg and 3 kg for grazing and silage fields respectively. Grazing will be hit hardest if P applications are forgone, while silage yields are more at risk if K applications are missed or reduced. It should be remembered that K is also lost through leaching, and with above average rainfall comes above average K leaching losses.
The upshot of declining soil P & K fertility is poorer grass growth, and reduced nitrogen use efficiency which hits both the pocket as grass is the cheapest feed source and potentially water quality and nitrous oxide emissions. If farmers apply the same amount of nitrogen on fields with declining soil P & K fertility, then lower yields capture less nitrogen, leaving more residual soil nitrogen at risk of soil denitrification and leaching.
Protecting the long-term productivity of autumn sown leys
The cut off point for establishing an autumn ley was generally early September but many are now pushing this date later into September successfully. It’s important that these autumn sown leys are managed adequately to ensure they perform the next year.
The autumn weather can make the timing of the first grazing difficult, but in general the first grazing is left too late. New leys should be grazed as soon as the new roots are strong enough to withstand grazing. We can check for this by using our fingers to see if the root stays anchored in the ground when the plant is pulled.
Early grazing allows light into the base of the ley which will encourage tillering. A light grazing by calves, young stock or sheep is preferable. Bigger animals have more of a tendency to cause sod pull and poaching at this time of year. A first grazing can usually take place when the sward is at 6 – 8 cm’s in height.
Don’t be tempted to allow grass to build up on these new leys for a late cut of silage. This will inhibit tillering, resulting in more open swards which will be more susceptible to weed germination in the spring. Low winter covers will also benefit clover performance come spring.
If soil fertility is not known, then a soil test should be taken. Correcting soil pH and supplying any necessary P & K is a must for the success of a new ley, especially those which include clover.
Proactive grassland management this September and forage budgeting
Growth rates are below average around the country and this will likely result in growth rates dropping below demand earlier than usual in September. Careful autumn grassland management at this point in the year can save money and save on silage. Another key job for September on livestock farms is forage budgeting to identify any potential forage shortfall this winter and spring.
Average farm covers should be hitting 1,000 kg DM/ha by late September and most farms should be out to a 35-day rotation. This means a 35 ha milking platform would be grazing 1 ha per day. If the daily grass allowance based on this rotation length is not enough to meet demand, consider reducing stocking rate or introducing supplement. A minimum 30-day rotation needs to be maintained, to grow and utilise more grass.
Nitrogen applied now is required to grow grass for the last rotation. Where grass demand is high, we recommend YaraBela Nutri Booster at 100 kg/ha in September. Better to take advantage of grass growth now and build covers in September when the fundamentals for growth are better. Applying nitrogen from mid-October onwards is likely to be uneconomical. Apply nitrogen to paddocks that will likely give the best response. If P & K needs topping up, then a quality NPKS such as YaraMila EXTRA GRASS at 90 kg/ha should be used.
When pre-grazing yields are high, use strip-wires to maintain your target residuals. Try and graze paddocks with heavier, less free draining soil types earlier in the rotation to improve graze-outs.
Maintain High Output on Perennial Ryegrass White Clover Swards
How effectively can you apply low nitrogen (N) rates on PRG/white clover swards on intensive rotationally grazed platforms using high N fertiliser products like urea and at the same time apply the phosphate (P), potash (K) and sulphur (S) that these swards require? Clover requires very good soil P & K fertility because it hasn’t got the rooting mass of PRG, so is more at risk of transient nutrient deficiencies.
‘Clover is a shallow rooted species with around 15% of the root density of perennial ryegrass making it much less competitive for soil nutrients. Regular applications of a P & K compound fertiliser throughout the growing season are necessary for high levels of clover productivity and biological N fixation.’ - Dr. James Humphrey’s, Teagasc, Solohead Farm
By applying P, K & S little and often during the growing period you are providing clover with the P, K and S it needs to establish and reach a desirable sward content, fix atmospheric N, and remain persistent in the sward. YaraMila ExtraGrass is an ideal solution to low N application rates on these swards, ensuring maximum nutrient coverage of N, P, K & S throughout the season.
YaraMila ExtraGrass is a homogeneous, uniform-sized, compound fertiliser where all the nutrients are contained in every particle. This eliminates any segregation and allows even application and distribution of each nutrient across the whole bout width. The product contains nitrate N for that quick and reliable N response even in drier conditions.
Things to consider with your grazing management this Autumn
The focus of autumn grazing management is to increase the number of days at grass and animal performance, but also to set the farm up during the final rotation to grow grass over winter and provide grass the following spring.
Because grass remains leafy now, rotation length can be extended from the 2nd week in August. The focus of this period is to gradually build pre-grazing covers, targeting covers of 2,000kg to 2,200kg DM/ha in mid-September. Be careful not allow covers build beyond 2,500kg DM/ha for grazing, as utilisation is poorer. We want to avoid taking paddocks out for silage after the start of September, as these paddocks won’t have enough time to re-grow to make a significant contribution to the last rotation.
If Autumn nitrogen is going to be spread, it should be spread in August and September. The growth response to October applications is likely to be significantly lower and may not be economical. Our Calcium Ammonium Nitrate based fertiliser YaraBela AXAN with sulphur at 110kg/ha is an appropriate rate for applications during August and into the first half of September. If P & K needs topping up then a quality NPKS such as YaraMila EXTRA GRASS at 110 kg/ha should be used.
Drier or ‘earlier’ paddocks should be grazed from mid-September and then closed off from October onwards. Regrowth on these parts can be carried over the winter months for grazing first in the spring.
Fertilising aftermaths to boost grass supply
The importance of aftermath grass will vary on farms, with a whole range of factors affecting how much grazed grass will be required after the last silage cut is taken. There are two considerations to address when fertilising these aftermaths. Ensuring that the phosphate (P) and potash (K) requirements of the previous silage crops have been met and supplying enough nitrogen (N) and sulphur (S) to grow enough aftermath grass to meet livestock demand.
Unless soil P & K fertility is maintained at current levels on silage fields then it is likely that next year’s silage yields will suffer. On most farms, the N rate remains constant for silage crops from year-to-year, but with deteriorating soil P & K fertility you end up with less grass for every kg of N applied. Calculate what the offtakes and inputs are to see if P & K needs topping up. Use a suitable quality true uniform compound fertiliser, such as YaraMila NK Sulphur or YaraMila ExtraGrass.
The N requirement of aftermaths will depend on grass demand. Where there is high demand, then apply up to 35 kg/ha of N per application in August and September. If P & K are not needed, then use YaraBela Nutri Booster at 140 kg/ha and if they are needed use one of the YaraMila compounds mentioned in the previous paragraph at a N rate of up to 35 kg/ha. It’s important to apply this fertiliser on as soon as possible, to get grass off to a good start.
Grass mineral analysis – a useful management tool
Grass mineral analysis can be a useful tool to check nutrient levels, both macro and micro-nutrients levels in grass swards. Silage samples are regularly tested for minerals, but it’s usually with a focus on animal nutrition rather than crop nutrition. So, there is certainly more scope on both grass for grazing and silage to utilise mineral analysis to improve yields and nutrient use efficiency.
A farmer two years ago asked me to have a look at their 1st cut silage mineral analysis report which highlighted a couple of potential problems. Because it was a composite sample from a number of different fields, it warranted a closer look the following spring, so three silage fields were sampled in May, 10 days before harvest.
The three fields had received the same nutrients, a combination of slurry and YaraMila EXTRAGRASS (27-5-5+6%SO3) in the spring. Nitrogen, phosphate, potash, sulphur, calcium and magnesium were within the optimum range for two of the fields, while the report on the third field indicated that phosphate, potash, calcium and magnesium were low or very low.
These three fields had the same history of manure applications, and the most recent soil analysis indicated good levels of soil phosphate and potash. The difference was that the field which had the low grass nutrient levels also had a low soil pH (5.4). This makes sense, as soil pH affects nutrient availability. This again highlights the benefit of analysis and in particular acting on soil test results and correcting low soil pH.
Achieving more effective grassland weed control
If we’re spraying to control grassland weeds in the weeks ahead, spray selection and spraying weeds at the right growth stage are key points for effective weed control. We are also seeing advantages of applying a multi nutrient foliar fertiliser with the herbicide to improve outcomes.
The foliar fertiliser stimulates the growth of both the target (weeds) and non-target species (grass). An actively growing weed will translocate the herbicide around the plant and down into its roots more effectively, than a less active growing weed. It’s important to get the herbicide down into the roots to completely control grassland weeds such as docks and thistles.
Grass herbicides can often ‘check’ grass growth after spraying and especially when growing conditions are not ideal. The application of a foliar fertiliser in combination with the herbicide helps offset this ‘check’ on swards. Also, in newly established leys, foliar nutrition can give grass seedlings a much needed nutrition boost, which promotes tillering, helping to reduce light and space for any new germinating weeds.
We recommend YaraVita Croplift Pro at a rate of 5 kg/ha (2 kg/acre) for inclusion in a tank mix with your chosen grass herbicide. This foliar fertiliser containing multiple nutrients and micronutrients for foliar application on grassland is ideal at times of stress or periods of rapid growth. It has excellent plant absorption properties, giving an immediate and long-lasting feeding effect on grass and herbal leys.
Taking advantage of Maize foliar nutrition
Yara’s maize trials, have demonstrated the positive effect that combining foliar nutrition and biostimulants had on crop performance. In last year’s trial the combination of our crop specific product for Maize - YaraVita CROP BOOST (5 L/ha) and the biostimulant - YaraAmplix Optitrac (2 L/ha) applied at the 5 leaf stage increased dry mater yields by 16%, equal to 2.5 tonnes of dry matter per hectare.
When applied together, YaraAmplix Optitrac complements the nutritional effects of YaraVita CROP BOOST. The unique combination of selected bioactive components and nutrients in YaraAmplix Optitrac activates the plant’s metabolic processes to enhance nutrient use efficiency and tolerance to abiotic stress for example due to the application of a herbicide. The two YaraVita products work in harmony to maximise the ability of YaraVita CROP BOOST to promote root and plant growth and efficiently use the plant’s energy reserves.
YaraVita CROP BOOST is formulated for foliar applications on maize, containing a high concentration of phosphorus, zinc, magnesium and potassium. Yara conducts nutrient specific trials to prioritise nutrients according to their impact on crop growth and development. Once these are established then crop-specific products can be formulated to deliver enough quantities of these specific nutrients.
The results of two years of maize trials in both the UK and Ireland have demonstrated an economic justification of using YaraVita CROP BOOST and YaraAmplix Optitrac together. There is a very strong case to adopt the YaraVita Maize Programme at the 4 – 6 leaf stage to minimise the risk of nutrient deficiencies and abiotic stress in Maize and maximise yields.
Fertiliser application advice for first cut silage crops
Fertiliser applications for first cut silage have been really hampered by the weather since mid-March. This is a very worrying situation as these first cuts constitute a large part of next winters forage.
Remember grass will start heading out at the same time as usual, so allowing a longer first cut growth period might be okay to increase grass silage yield for some but the quality of this silage will be lower. Also, the second cut regrowth will be slower, so while you might gain extra yield on the first cut, you will lose out on first cut quality and second cut yield.
When it comes to early May, check the base of the sward for dead/decaying leaf and stem. What happens at the base of the sward has as great an effect on feed value as seed head emergence. This dead decaying material might be as a result of water logging or just the wet conditions especially where there were heavier covers of grass on fields and in some cases this grass has lodged whereas in other years it mightn’t have. If there is dead material at the base, then consider cutting sooner rather than later.
There are a couple of first cut scenarios being faced by farmers presently:
1. Fertiliser and slurry have been applied, but the grass looks backward and isn’t a lush green colour.
Grass growth has been affected by wet soil conditions and overcast weather. Nitrogen losses to leaching will have been greater due to the above average rainfall this spring, but putting a figure on this is very difficult. Should more nitrogen be applied in this case? It will depend on when the slurry and fertiliser was applied. If slurry applications were applied in Jan/Feb and fertiliser was applied before the 20th of March, then an application now of a bag/acre of YaraBela Nutri Booster (25 units N/acre) is justified if the anticipated mowing date is circa 20th of May.
2. Slurry has been applied but not the nitrogen fertiliser.
If applying nitrogen or an NPK fertiliser, apply as soon as possible. Have the fertiliser in the yard ready for spreading. If slurry was applied a minimum of 2 weeks ago, then the silage crop will utilise 2 units/acre of nitrogen per day from the date of fertiliser spreading to the anticipated harvest date. A nitrogen product such as YaraBela Nutri Booster or an NPK such as YaraMila SulphurCut would be ideal in this situation.
3. Nothing applied to date.
Be very careful applying slurry on first cuts at this late stage. Only apply if there are light grass covers (<750 kg DM/ha) and the slurry is dilute and is being applied by trailing shoe or dribble bar. Otherwise, delay slurry applications until after harvest because of the risk that residues from the slurry will persist on the grass up to harvest or that these residues are picked up off the soil surface at mowing/raking/picking up.
As for the nitrogen rate, calculate the number of days from when the nitrogen fertiliser is applied to the anticipated harvest date and then use the 2 units/acre of nitrogen per day rule. If slurry is being applied, account for the available nitrogen in the slurry when calculating how much nitrogen fertiliser is required. If slurry is not being applied, and soil P & K indices are index 3 or less then use an NPK fertiliser such as YaraMila Sulphur Cut.
Another option that some farmers might be considering for this scenario might be to cut in the next two to three weeks if field conditions allow and then focus on the second cut. If this is the strategy you choose, then only if good ground conditions exist at harvest to minimise soil contamination. This late April/early May mown grass is more likely to have lower sugar levels, so this would need to be considered at mowing. Achieving a good wilt and using a silage inoculant could help counteract sub-optimum sugar levels.
Fertilising aftermaths to boost grass supply
The importance of aftermath grass will vary on farms, with a whole range of factors affecting how much grazed grass will be required after the last silage cut is taken. There are two considerations to address when fertilising these aftermaths. Ensuring that the phosphate (P) and potash (K) requirements of the previous silage crops have been met and supplying enough nitrogen (N) and sulphur (S) to grow enough aftermath grass to meet livestock demand.
Unless soil P & K fertility is maintained at current levels on silage fields then it is likely that next year’s silage yields will suffer. On most farms, the N rate remains constant for silage crops from year-to-year, but with deteriorating soil P & K fertility you end up with less grass for every kg of N applied. Calculate what the offtakes and inputs are to see if P & K needs topping up. Use a suitable quality true uniform compound fertiliser, such as YaraMila NK Sulphur (YaraMila Zero P cut) or YaraMila ExtraGrass.
The N requirement of aftermaths will depend on grass demand. Where there is high demand, then apply up to 35 kg/ha of N per application in August and September. If P & K are not needed, then use YaraBela Nutri Booster at 140 kg/ha and if they are needed use one of the YaraMila compounds mentioned in the previous paragraph at a N rate of up to 35 kg/ha. It’s important to apply this fertiliser on as soon as possible, to get grass off to a good start.
4 Steps to successful Autumn reseeding
A new reseed can often be the most challenging crop to establish on grassland farms. The main benefits of new swards are improved dry matter (DM) yield, and improved nutrient use efficiency. Reseeding in the Autumn has always been more popular with farmers, but it’s important not to leave them too late to establish as it can make managing them for weeds and grazing more difficult. Here are our 4 key steps to success.
Step 1: Identify poorly performing paddocks.
Step 2: assess their content of desirable grasses. If this is less than 60% consider re-seeding. Annual meadow grass and other weed grasses produce lower yields, poorer feed quality and do not respond well to applied nutrients. Yield will be reduced by 1% for every 1% of area covered in weeds.
Before you start, be sure to complete Step 3: take a soil test and act on the results. On mineral soils the optimum pH for grass is 6.3. Failing to correct pH will severely impact the success of your reseed. Choose only varieties from the Recommended Grass and Clover Lists (RGCL) and pick those that suit your farm.
Step 4: Provide new swards with the correct nutrients at sowing. Failure to do so will hinder establishment. Slurry can be used to provide part or all the nutrient requirements. With good soil fertility (P & K index is 2), then the P2O5 & K2O requirement is 50kg/ha for both. If clover or other legumes are not part of the mixture, then an application of 20-30kg/ha of N can be applied to aid establishment. New leys have a greater requirement for phosphate to help with root development. Good seed soil contact is essential, so roll after sowing.
My Top Tips: Weeks 4-6 (post-emergence) apply herbicide to prevent weeds competing for nutrients and space. Combine this with a light grazing when grass height is at 8 – 10 cm to promote new shoots, and thus the long-term productivity of your new sward.
Keeping up grass supply during May and June with YaraMila ExtraGrass
Grazing conditions have certainly been a challenge this season, and unlike this time last year, we’re looking for the rain to stop. Thankfully, for beef and sheep farmers the outlook looks more promising this year with livestock values up on last year, and a return of nearer to normal fertiliser prices. There is a worry though that the significant drop seen in phosphorus and potash fertiliser applications last year, disproportionately affects beef and sheep farms, which does not bode well for forage production on these farms if not rectified.
From a nitrogen (N) perspective, it’s important to note that for farmers who did cut N fertiliser applications last year, doing so again this year will hit grass growth even harder this year as soil N supply is run down from 2022. Where phosphorus (P) & potash (K) offtakes from grazing and silage were not met from fertiliser or manures last year, then soil P & K fertility will have declined. With lower P & K fertility comes a lower N response!
Applying a quality NPKS fertiliser like YaraMila ExtraGrass (27-2.2-4.2+2.4%S) at a rate of 125 kg/ha in May and again in June will increase grass supply at a critical time now on beef and sheep farms and ensure lactating livestock reach and sustain peak milk production to grow lambs and calves quickly. For growing beef cattle, compensatory growth is still strong during May, but cattle need a supply of grass to take advantage of this phenomenon. With silage fields closed up, the grazing area is at its highest stocking rate so enough grass must be grown during this key period on beef and sheep farms.
P is a key nutrient for grass. Its role in energy supply, root growth and tillering makes its availability crucial for grass growth. The plants requirement for P is small in volume when compared to N BUT its availability is essential. For grazing, P applications into May and June are important to maintain grass growth, herbage P concentration for growing livestock, and importantly to maintain and build soil P fertility. We should be looking to apply 10 kg/ha of P per annum to maintain soil P fertility, which can be met in part or full from applying YaraMila ExtraGrass.
Typically, the phosphate in fertiliser is 100% water soluble; this however creates its own problems. As soon as you apply water soluble phosphorus to a soil, this soluble phosphorus becomes slowly fixed by iron and aluminium. The phosphate contained in YaraMila ExtraGrass is a mix of water soluble phosphate and Di-Calcium Phosphate (DCP). This DCP is not fixed by the soil but becomes available as it is triggered by weak acids from grass root exudates. This ideal combination of two phosphate fractions rather than one results in superior availability of P for grass.
The latest Teagasc National Soil Fertility Trends for 2021 show over 50% of drystock farms have soil test results that are below the optimum K index, so it’s important K soil fertility is not neglected. Even though K offtakes are low for grazing, it’s a key nutrient to optimise N response.
ExtraGrass is a quality uniform compound which can be spread uniformly, with a maximum of landing sites for each nutrient. Beware blended fertilisers will have only one tenth the number of P & K landing sites that ExtraGrass will have. You also have the assurance with a Yara product that the analysis printed on the bag is the analysis in the bag.
Fertiliser advice for growing fodder beet
Fodder beet crops needs adequate crop nutrition if they are to meet their energy and protein yield potential. It is only a cost effective crop to grow if it yields well. We should expect a well manged crop to hit dry matter yields in excess of 20 tonne/ha.
Growing fodder beet has been traditionally for feeding to housed livestock but its use for grazing in-situ over the winter has grown in popularity over the last number of years. For these grazed crops it’s about the proportion of root to leaf (or energy to protein) to meet the nutritional requirements of grazing livestock.
A high yielding crop of fodder beet can have nutrient uptakes of 250 kg, 90 kg, and 580 kg of nitrogen (N), phosphate (P) and potash (K) per ha respectively over the course of the growing season, so for these high yields to be achieved, the nutritional requirements of the crop need consideration. Using soil test results to determine the crops nutrient requirements from RB209, is a start.
The P & K requirements can be met in-part or in-full from organic manures with any deficit being made with P & K fertiliser. Part of the K requirement of beet crops can be replaced by salt and there is always a benefit in applying agricultural salt in combination with K particularly on low K index soils. Salt and K containing fertilisers should be applied at least two weeks in advance of drilling to mitigate any effect that the high chloride levels in these fertilisers might damage beet seedlings.
If applying organic manures, they need to be incorporated well in advance and incorporated into the seedbed. Usually all the P & K requirements are applied to the seedbed before planting. We are aiming to supply 150 kg/ha of YaraBela AXAN (40 kg/ha of N) into the seedbed, with a second application of 370 kg/ha of AXAN (100 kg/ha of N) when the crop is established.
Because beet is particularly susceptible to boron and manganese deficiency, we recommend a foliar application of YaraVita Brassitrel at 3 L/ha at the 4 – 6 leaf stage to meet the crops requirement for these necessary micronutrients. A second application 14 days later may be necessary where there is a known soil boron and manganese deficiency. Brassitrel Pro also provides N, molybdenum, magnesium and calcium to meet any shortfall during this critical phase of canopy development. Reaching canopy closure as soon as possible maximises light interception and maximises yield potential.
N is key in establishing the leaf canopy early to capture as much light as possible over the summer months, but also important later on in the growing cycle of the crop to promote and maintain leaf canopy later into the autumn and winter to increase both root and leaf protein content. New Zealand research has demonstrated that in Autumn beet crops can be accumulating up to 250 kg/ha of dry matter per day. So there is still a very high demand for both N and K during the autumn period. Traditionally two N applications are applied on fodder beet, in the seedbed and at establishment but we are also recommending a slow release foliar N application of YaraVita Safe-N 300 at 25 L/ha in August to promote top and root growth during this Autumn period.
For more information on growing fodder beet and other forage brassica crops contact your local Yara representative for advice.
Spring nitrogen management to promote grass growth
The timing and rate of the first nitrogen (N) application in the spring always sparks debate. Nonetheless, many farmers with dwindling forage stocks will be looking forward to putting stock out to grass this spring as soon as they can. But what can we do to increase the availability of grass this spring on grass farms.
The same principles apply whether its grass for grazing or silage. We know that applying a N source (as slurry or fertiliser) when soil conditions and temperatures are at 5-6oC and rising and with a favourable weather forecast will increase the supply of grass over the subsequent 6 weeks compared to holding off until later in the spring when growing conditions are more favourable.
N has the effect of stimulating growth earlier than it would otherwise be. The response to this early N will be greatest for more productive ryegrass swards. The exact timing of this initial application will vary across the UK, for the south of England and Wales it is probably early February but for Scotland it may well be a month later.
For silage, tack grazing should have finished in December, as over grazing and grazing into the new year is going to slow grass growth and is shown to reduce 1st cut silage yields. Slurry is a valuable source of nutrients for 1st cut silage and often tanks have to emptied in January, but if applications can be delayed till the soil conditions outlined in the second paragraph exist then slurry N utilisation will increase.
As a guide, if slurry is applied in January then any nitrogen, phosphate, potash or sulphur fertiliser that is required should be applied by the end of February/early March. For later slurry applications, then the fertiliser should be applied no later than 6 weeks from the planned cutting date. These 1st cut silage crops need a sulphur containing fertiliser as there is not enough sulphur in slurry alone.
For grazing, we would recommend applying 80 kg/ha of Nutri Booster when the soil reaches the conditions outlined in the second paragraph and then a second application of 160 kg/ha of Nutri Booster 4-5 weeks later when growing conditions are hopefully improving. In terms of herbage growth, N response and N use efficiency, a recent study by Teagasc, Moorepark demonstrated that the most effective strategy for early spring N applications was to apply total of 60 kg/ha of N by early April, split 20/40 for the first and second application.
Last but not least, don’t leave it till the last minute to buy fertiliser as delivery might not be as prompt as you might like. Not having the fertiliser could cost you more if you’re later applying it. You end up with less grass, making costly fertiliser even more expensive.
New research: Spring N application strategies for grazing
A recent study at Teagasc Moorepack investigated the impact of applying 3 rates of spring nitrogen (N) fertiliser (30,60 or 90 kg N/ha) by April 1st, on two N application dates, 3rd Febraury and 19th March, with three different rate strategies (split between Febraury and March); 0:100, 50:50 and 33:66. The highest spring herbage production was reported on the 90 kg N/ha, followed by the 60 kg and 30 kg the lowest (3,026, 2,753 and 2,308 kg DM/ha, respectively). Higher N rates lead to a reduction in N recovery and a lower response to N application.
The 90 kg N treatment had the lowest N response per kg N applied, followed by the 60 kg N with the 30 kg N the highest (15.7, 18.2 and 21.0 kg DM/kg N). These are all greater than previously reported response figures of 10-13 kg DM/kg N, and greater than the required economic breakeven point.
The impact of application strategy, across all of the rates of N applied, when zero N was applied in February and all was applied in March (0:100), resulted in a lower spring herbage production of 200 kg DM/ha, compared to either of the 33:66 or 50:50 strategies. The 33:66 strategy (27.3 kg DM/kg N) had the greatest N response compared to the 0:100 or 50:50 (14.3 and 21.1 kg DM/kg N, respectively). High levels of N in a single application in spring, will result in too high a level of available N for the plant to utilise, and does not result in increased levels of herbage production.
Selenium trial results give further credibility to selenium enriched fertilisers
Yara undertook a farm trial this year to investigate the effectiveness of its’ selenium enriched Booster range, by comparing the blood selenium levels of two groups of in-calf dairy heifers - one group having grazed an area that had been fertilized with the selenium fortified YaraMila STOCK BOOSTER S (25-5-5+5%SO3+Na+Se), while the second group had grazed an area fertilised with YaraMila EXTRAGRASS (27-5-5+6%SO3).
The hypothesis is that by enriching the grass with selenium, you therefore increase dietary selenium which will support healthier levels of the nutrient in the animal’s blood. This form of selenium is much more available to the animal, compared to inorganic selenium sources found in concentrates, licks and boluses which are less available to the animal.
The heifers rotationally grazed their respective areas for 3 months (from May until August) and the relevant fertilizer was applied three times during that period. At the end of the trial, blood tests were taken again. The average blood selenium levels in the heifers grazed on the area receiving the selenium fortified fertiliser (Stock Booster S) were 50% higher than the group of heifers grazed on grass fertilised with the standard NPK (EXTRAGRASS).
Herbage analysis also indicated that the group grazing the area where Stock Booster S was applied had double the selenium herbage concentration, compared with the untreated area. The outcome of this trial gives us further confidence, that the Booster range of fertilisers can influence positively the selenium intakes of grazing livestock.
For more of Yara’s trial results from this season please visit Agronomy Advice.
Soil fertility is vital: Test It, Review It & Take Action
At some stage, over the next couple of months, plan to do some soil testing if you haven’t done so already. Once you have the results, don’t file them in a drawer! Review them and use them to put together a nutrient management plan (NMP) for 2023. Your NMP is about prioritising how to use organic and mineral nutrients on the farm in the most cost effective way possible.
Too often, organic manures are applied on the same parts of the farm, year after year. There are plenty of reasons why this is done, but it’s not maximising the potential value of this valuable resource. Using umbilical spreading systems may be an option to target other areas of the farm. Target cattle slurry at low K index soils as it’s a cost effective potash source.
Intensively stocked grassland farms should consider soil testing more regularly. By soil testing every 2–3 years, you’re in a better position to monitor soil fertility trends. Fertiliser recommendations are not an exact science, hence soil testing more frequently together with measuring grass yields will help you fine tune your NMP for every paddock or field on your farm.
Remember, grass requires a continuous and balanced nutrient supply from the soil to achieve its production potential. If a farmer is regularly soil testing, say every three years, then the £1 ha/year cost is money well spent.
For more information on soil testing this spring, visit Yara analytical services.
Grazing management of new leys this autumn
Many new leys sown in August may be fit to graze now, but these newly sown swards require specific management practices to get the most from them.
There is a tendency to delay the initial grazing of these new leys, which leads to grass covers building up. Then, when animals graze them, there’s a high degree of sod pulling. This first grazing is important. New leys should be grazed as soon as the new roots are strong enough to withstand grazing. We can check for this by using our fingers to see if the root stays anchored in the ground when the plant is pulled.
Early grazing of these leys is important as it allows light into the base of the ley which will encourage tillering. A light grazing by calves, young stock or sheep is preferable. Bigger animals have more of a tendency to cause sod pull and poaching at this time of year. A first grazing can usually take place when the sward is at 6–8 cm’s in height.
Don’t be tempted to allow grass to build up on these new leys for a late cut of silage. This will inhibit tillering, resulting in more open swards which will be more susceptible to weed germination in the spring. Low winter covers will also benefit clover performance come spring.
If you haven’t soil tested before seeding, then it would be a good idea to do so before the spring. New leys are more productive and utilise nitrogen more efficiently but only if soil fertility is adequate.
Research confirms sulphur benefits on grassland
New sulphur (S) research from Teagasc in Ireland highlights some interesting findings on S applications on grassland. Using lysimeters and a sandy loam soil they found N + S applications increased grass yields by 30%, compared to N only plots over the course of 7 cuts. Treatments received 250kg N/ha, divided over 7 splits. For the two slurry treatments, there was a 24% yield increase by using a N + S fertiliser with slurry compared to N only fertiliser with slurry.
Apparent Fertiliser Nitrogen Recovery (AFNR) which is a measure of how much of the applied N was taken up by the crop was also increased with sulphur applications. N only plots had a AFNR of 39%, compared to 49% for the N + S treatments. For the slurry treatments the addition of mineral S in the fertiliser increased the AFNR by 13%.
The leachate from the treatments amounted to 68% of total rainfall over the 12 month study. Nitrate leaching loses per ha for the N only plots was 48.2kg NO3-N, whilst the N + S treatment was 26 kg NO3-N which was only 2kg greater than the Zero N control treatment. The nitrate leaching losses for the slurry treatments were very surprising. The N + slurry treatment had losses of 82.8kg NO3-N, in contrast to the N + S + slurry treatment which had losses of 33kg NO3-N.
The study concluded that S fertilisation is potentially important for increasing grass yield, N use efficiency and reducing nitrate leaching losses on certain soils.
Autumn grazing management
The focus of autumn grazing management is to increase the number of days at grass and animal performance, but also to set the farm up during the final rotation to grow grass over winter and provide grass the following spring.
Because grass remains leafy, rotation length can be extended from the 2nd week in August. The focus of this period is to gradually build pre-grazing covers, targeting covers of 3,500kg to 3,700kg DM/ha in mid-September. Be careful to not allow covers build beyond 4,000kg DM/ha for grazing, as utilisation is poorer. We want to avoid taking paddocks out for silage after the start of September, as these paddocks won’t have enough time to re-grow to make a significant contribution to the last rotation.
If Autumn nitrogen is going to be spread, it should be spread in August and September. As you can see from the graph, the growth response to October applications is likely to be significantly lower, and may not be economical. Our Calcium Ammonium Nitrate based fertiliser YaraBela NUTRI BOOSTER, with sulphur and selenium at 120kg/ha, is an appropriate rate for applications during August and into the first half of September.
Drier or ‘earlier’ paddocks should be grazed from mid-September and then closed off from October onwards. Regrowth on these parts can be carried over the winter months for grazing first in the spring.
Don’t let potash hold your 3rd cut back
If you’re planning to fertilise 3rd cuts, then we should be aiming to apply between 70 – 80 kg/ha of N. If this is not the final cut, then stay at the lower end of this range, and for those taking only 3 cuts - then aim for the higher end of the range, as the growing period is generally longer. Spread slurry as soon as is practical after the 2nd cut harvest, and then a week later follow up with the fertiliser.
From both a yield and silage quality perspective, a sulphur (S) containing fertiliser should be used. At optimum N rates, we see a 10% increase in dry matter yields on average where S is applied, rising to 20% on very responsive lighter soil types. During dry weather, sulphur availability to the grass plant becomes even more important.
Pay particular attention to potash (K) at this stage of the year. A 23 and 15 t/ha crop of 1st and 2nd cut respectively, will remove 310 kg/ha of K2O. A 3rd cut is likely to remove another 75 kg’s, so it’s worth calculating how much K has been applied. If slurry contains 2.5 kg of K2O per cubic metre, that’s 154 cubic metres of slurry needed to replenish the K offtake from 3 cuts.
If slurry can meet the P & K demands of the 3rd cut, then an N + S fertiliser - such as YaraBela Nutri Booster could be used. If not, YaraMila NK Sulphur is an option on 3rd cuts if P is not required.
To check out Yara’s full range of quality compound fertilisers, please visit https://www.yara.co.uk/crop-nutrition/fertiliser/.
More effective grassland weed control with foliar nutrition
When getting the sprayer out to control grassland weeds on grass this summer, it’s worth considering adding a foliar fertiliser to the tank for two reasons:
- The effectiveness of herbicides on grassland can be improved if the correct foliar fertiliser is tank-mixed with the herbicide. This foliar fertiliser is absorbed by both the target and non-target species and stimulates plant growth, including the weeds. The plants which are growing actively are more likely to translocate the active ingredients within the herbicide effectively around the plant and down into the roots. This results in the herbicide working more effectively on the target weed species.
- A phytotoxic effect of grass herbicides is often seen as a ‘check’ in growth on newly sprayed swards, and especially when growing conditions are not ideal. The application of a foliar fertiliser, in combination with the herbicide, helps offset any side effects of the herbicide on the sward. An added bonus on newly established leys is the improved growth of grass seedlings, which in turn will promote tillering - reducing light and space for any new germinating weeds.
We recommend YaraVita Croplift Pro at a rate of 5 kg/ha (2 kg/acre) for inclusion in a tank mix with your chosen grass herbicide. This foliar fertiliser, containing multiple nutrients and micronutrients for foliar application on grassland, is ideal at times of stress or periods of rapid growth. It has excellent plant absorption properties, giving an immediate and long-lasting feeding effect on stressed grass crops.
A fine balance between quantity and quality
As I watch farmers about to start taking their second cut of the season, I reflect that not so long ago, the three-cut system used to dominate. In recent years we’ve seen farmers shift to a four and even five-cut system. But why have we seen that shift?
Whilst three cut silage systems can yield extraordinarily well and produce good quality silage, they do require higher inclusion rates of concentrate feed to balance milking cow rations. By moving to 4 and 5 cuts per season, silage quality improves because you’re cutting grass with a higher leaf-to-stem ratio. There are some drawbacks, such as higher machinery costs with cutting more frequently and there can be lower overall DM production, but in general, the advantages outweigh the disadvantages. Milk from forage figures improve as well as herd production and health as forage makes up a greater proportion of the ration.
A trial conducted in Northern Ireland a few years ago, comparing 3-cut and 4-cut silage systems, found total silage dry matter (DM) yields for the 3 and 4-cut systems were 13.4 t DM/ha and 12.3 t DM/ha respectively. The average DM of the 3-cut system was 31.9% and 34.4% for the 4-cut system. The average metabolizable energy (MJ/kg DM) was 10.7 and 11.3, and average protein (% DM) was 14.3 and 16.4 for the 3 and 4-cut systems respectively.
Cows on the 4-cut system had higher silage intakes (+9.5%), and produced more milk (+6.4%) with higher milk protein (+2.1%) but slightly lower fat content (-2.4%). Silage production costs were calculated as £114 and £135 t/DM for the 3 and 4-cut system respectively. This includes a land charge, reseeding cost and a contractor for harvesting.
Total feed costs of 23 pence/cow/day higher with the 4-cut system, but the value of milk produced was 71 pence/cow/day higher. The margin-over-feed cost was 48 pence/cow/day higher for the 4-cut system. At the time this was calculated for a 100 cow herd over a 180-day winter period, the 4-cut system resulted in a £8,640 increase in margin-over-feed costs.
Fertiliser application advice
To give your growing grass just enough fertilizer to flourish, whilst maximising nitrogen use efficiency and saving on input costs, we would recommend that you plan how much nitrogen is required to grow this 3rd cut efficiently. You’ll want to apply 70-80kilos of nitrogen per hectare on third cuts. The lower end of this range for shorter growing periods and upper end of this range with longer growing periods.
But don’t forget to take into account any slurry applications. To calculate how much nitrogen you’re likely to apply through your slurry you can do one of three things: (1) use RB209, (2) use a slurry analysis taken earlier in the year, or for the most precise calculation (3) undertake a new slurry analysis to calculate exactly how much nitrogen is present. Once you know how much you’re able to apply through your slurry, you’ll know how much mineral nitrogen fertiliser you’ll need to top it up with. Remember sulphur is a key nutrient on these crops to optimise nitrogen use efficiency.
Spread your slurry straight after you’ve taken your third cut and then follow that up with your mineral fertiliser six days later.
If you’re worried about your input costs, don’t forget to use AHDB’s new grassland cost-benefit fertiliser calculator to protect your return.
Improve your maize yield potential with foliar nutrition
Due to its high yield potential, Maize also has a high demand for nutrients. Therefore these high yields of 40+ tonnes/ha can only be achieved if the crop can access enough nutrients via its roots, and as the plant grows, through foliar applications.
Zinc and magnesium deficiencies are the two most widespread nutritional disorders in maize. Zinc is important for photosynthetic activity and Magnesium is essential for the early establishment of the plant. A deficiency can often be reflected in reduced crop yield at harvest.
Phosphorus and potash are primary nutrients, however, many soils do not have the capacity to deliver an adequate supply. Where phosphate availability is reduced, because of soil pH, or where its uptake is impaired due to dry soil conditions, foliar phosphate will help. It is translocated from the leaf to the roots very effectively, maintaining root development.
One or more of the above is often deficient in the growing maize plant. This nutritional shortage is particularly important as the plant reaches the 4 to 5 leaf stage, as it is now that yield is being set. Maize stressed at this point can result in tall, thin plants, with poor root systems and reduced leaf area – and reduced leaf area captures less light, resulting in lower yields.
To overcome the risk of nutrient deficiency, apply foliar nutrients at the 4 to 5 leaf stage. YaraVita Crop Boost is specifically formulated for foliar applications on maize. It will deliver a high concentration of phosphate, zinc, magnesium and potash to maximise maize yield and quality this harvest.
Grassland agronomy advice
The latest grassland fertiliser and nutrition advice from the Yara agronomists.
Maize needs an efficient form of phosphate
A crop of maize can produce up to 50 t/ha of fresh weight in just 4 months. For this amount of growth over a short timeframe to happen there needs to be a healthy, extensive root system for nutrient uptake from the start.
Phosphate (P) is a very important nutrient, key for growing the root system the crop requires to sustain the rapid growth, as well as being part of the transfer of energy within the plant. Weather plays a role in the availability of P, if soils are cold and wet when the maize is planted then P in the soil will have a very low level of availability, which is why placing some at drilling helps this by providing immediately available forms.
Nutrient availability in general decreases in dry soils, as we’ve had recently, and this will restrict root growth and therefore the ability to support the crop later in the season.
So how do we get around this? A foliar application of phosphate is the best way to overcome these early deficiencies and give the crop a boost in energy levels, both of these will help the crop develop a better root system to support later growth. YaraVita Crop Boost contains foliar phosphate, together with useful amounts of zinc, magnesium and potash. Applying it at the 4-6 leaf stage is effective for fast, efficient uptake through the leaf.
Biostimulants can also help during periods of abiotic stress, such as dry conditions. Trial work carried out in 2021 showed that YaraAmplix Optitrac, a biostimulant product, increased the yield in maize when applied in combination with YaraVita Crop Boost, by up to 4.4t/ha.
Foliar nitrogen for grassland?
There are farmers committing to replacing a large chunk of their soil-applied nitrogen (N) with foliar N in a bid to save money. This is certainly a risky strategy, considering the lack of grassland specific data for these foliar N products on first cut silage crops.
If we analyse one aspect of this strategy, that is – if we substitute 50 – 80 kg/ha of soil-applied N and replace it with 20 - 30 litres of a product that contains 30% N, we are expecting similar yield and protein content by applying only a fraction of normal practice.
If you expect that a good 1st cut yields 5.5 tonnes of dry matter (DM), with 3.0 tonnes of this coming from the soil's own N reserves through mineralisation etc. This means that approximately 2.5 tonnes is attributed to available N (as bagged N and/or slurry). If the crop contains a modest 14% DM protein, this equates to 123 kg/ha of N contained in that crop as protein. Since 2.5 tonnes is grown with N applied as slurry/fertiliser, that means this portion of the crop requires at least 56 kg/ha of N to synthesise the protein.
Therefore, a first cut at 14% protein requires at least 56 kg/ha of applied N as slurry and/or fertiliser. So where does the N come from to make this protein if you’re only applying 6 – 9 kg/ha of foliar N to replace the 50 – 80 kg’s of soil-applied N? Worth noting that this approach could also lead to nitrogen use efficiency (NUE) greater than 100%, which goes against the guidelines to target 80-90% NUE for sustainable yields and future production security.
A successful first cut starts now
Tonne for tonne, first cut silage is the most economical to make and usually the highest quality.
At the field level, the single biggest factor contributing to the cost of producing silage is the yield of the crop. The challenge for farmers is to maximise silage yield while at the same time achieving target silage quality for the production system on the farm.
Whether or not the first cut silage area is being grazed this spring, the important thing is that swards with yellow/dead material at the base must be grazed off. Where this material is not removed before closing, silage D-values will be 5-7 points lower. As for winter grazing sheep, they should certainly be away at this stage. Not doing so will lower your first cut yield.
As for slurry applications, if not applied already then it needs to be on as soon as possible, but only on very short grass and when field conditions allow. Using trailing shoe equipment gives some scope to apply where there are slightly higher grass covers. Make a note of application rates on each field, as this will need to be known to calculate the fertiliser rate.
With the current cost of fertiliser, it’s worthwhile testing slurry, especially if you haven’t done so before. Then by using both slurry and soil test results, we can calculate how much fertiliser is required on each field to grow a crop that fulfils both yield and quality expectations.
There will certainly be more scrutiny on fertiliser rates and timings this year. With many farmers looking to cut rates or use less conventional methods to fertilise first cuts in a bid to offset some of the rises in fertiliser prices.
As mentioned above, the fertiliser rate should be determined on a field-by-field basis, using the recommendations from Section 3 of RB209. On perennial ryegrass swards (PRG) with good growth potential and good soil fertility, the recommended nitrogen (N) rate is 120 kg/ha N where forage demand is high. For less productive swards (low PRG content) or where demand is lower, the N rate should be reduced to 90 kg/ha.
Where slurry has or will be applied, don’t feel rushed to apply N too early as the available N in the slurry is sufficient to keep grass growing during this early March period when grass N demand is low. Where no organic manures will be applied, then a third of your N rate should be applied as soon as soil conditions and soil temperatures (> 6oC) allow, with the remaining 2-3 weeks afterwards.
Where fields have a soil P or K index of 2 or less, and slurry/manure hasn’t met the requirement of 40kg/ha P and 80kg/ha K for the first cut, then an NPK fertiliser with sulphur should be applied. If not, Liebig’s law of the minimum will apply, and growth will be dictated by the scarcest nutrient!
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Managing your phosphate applications this spring
Phosphate (P) is a key nutrient for grass. Its role in energy supply, root growth and tillering makes its availability crucial for grass growth in the spring. The plant's requirement for P is small in volume when compared to nitrogen BUT its availability is essential.
On grazing farms, a portion of your total annual P requirement should be applied in early spring and I would suggest the lion’s share of it is applied by April. A fresh P application boosts availability at a time when its natural availability is reduced in wet cold soils in early spring and then in April and May when there is a very high demand for P as grass growth is peaking.
Typically, the phosphate in fertiliser is 100% water-soluble; this however creates its own problems. As soon as you apply water-soluble phosphorus to soil, this soluble phosphorus becomes slowly fixed by iron and aluminium. The phosphate contained in YaraMila Super Booster (25-2.2-4.2+2% S) is a mix of water-soluble phosphate and Di-Calcium Phosphate (DCP). This DCP is not fixed by the soil but becomes available as it is triggered by weak acids from grass root exudates. This ideal combination of two phosphate fractions rather than one results in superior availability of P for grass.
The maintenance requirement for phosphate (P) on grazed swards is 8 kg/ha, however, if your grazing platform is growing 15 t of dry matter with 80% utilisation, then your maintenance will be closer to 12 kg/ha.
Fertiliser use this spring – what to consider
High fertiliser prices will be a real challenge for farmers, and many face a dilemma of how much and what to buy. Where there’s scope to reduce grass or silage demand, then there is some wriggle room but if demand is going to remain the same then the opportunity to reduce fertiliser volumes from previous years is limited. Farmers may be faced with prioritising nitrogen (N) this year and skipping or reducing phosphorus (P) and potassium (K) applications in a bid to offset higher fertiliser costs.
Much of the commentary on reducing the impact of higher fertiliser prices has focused on slurry N utilisation, and there is scope on some farms to shift more applications into spring, however, a large proportion of farmers won’t have access to low emission spreading equipment (LESS). This cohort of farmers will have very little opportunity to lower their fertiliser N use from previous years without lowering grass production.
The most consistent and, usually, the best response to N from a bag or from slurry is during April and May. A reduction in N rates for grazing needs to be evaluated as it means the area normally closed-up for silage is less, or alternatively, the total N rate for 1st cut silage is reduced from previous seasons. When we lower our N rate (slurry + bag) on 1st cut silage, we will reduce the cost on a per acre basis but not per tonne. We end up with less silage in the pit with no real savings.
Spring N for grazing
One of the most important factors affecting spring grass growth on farms is the timing and quantity of the first spring N fertiliser application. This early spring grass is extremely valuable as a means of increasing the proportion of grazed grass in the diet. The on-farm response to early N can be variable (5 – 18 kg/DM per kg N, source: Teagasc), and coupled with higher N prices, getting timings right is more crucial than ever to make sure we justify the cost.
There’s always an element of debate around the right approach to spring N management. As a rule of thumb, the timing of the first N application should coincide with soil temperatures reaching 5 - 6oC. You can check soil temperature and soil moisture deficits (SMD’s) for different soil types on Met Eireann. If the SMD is negative, don’t apply fertiliser or slurry. Of course, a favourable weather forecast and good field conditions are also necessary when deciding when to spread.
For this first N application, we recommend using a product like YaraVera Amidas at a rate of 20 – 25 units N/acre. The second application should aim to deliver 35 – 40 units and be applied by the end of March on intensively stocked farms or mid-April on farms with a later turn-out date later and/or on heavier soils to take advantage of improving growing conditions. These rates are appropriate for newer swards with high perennial ryegrass content. On less intensively stocked farms or on swards that will be less responsive to N, then the above rates should be scaled back by 25%.
What about P & K?
Farmers may be considering a P & K ‘holiday’ this year in an effort to offset higher fertiliser prices. This needs to be considered carefully, particularly on farms that are highly stocked. The trouble is, while the cost-saving is known, the potential penalty in lost yield is uncertain so it’s a question of risk. This is in the short term, because longer-term, any negative balance of phosphorous and potassium where these are not applied this year, will have to be made up. You don’t get something for nothing.
We have not seen the same price rises for fertiliser P & K as N, and currently, NPK’s could be considered better value for money in comparison to straight N products. On dairy farms, it may be counterproductive not to maintain current soil fertility levels this year, at the expense of growing less grass. Also, there is no certainty that the cost of fertiliser P & K will return to early 2021 price levels.
For drystock farmers, it may be a case that N is prioritised, at the expense of P & K. This is not a situation that we want to see, but it may well be the reality on many farms. If only a percentage of the normal P & K rates can be spread, then late spring is the most opportune time to apply these on grassland approaching peak growth rates. Slurry should be prioritised for silage fields and the remaining if any for grazing fields/paddocks with low soil P & K fertility.
The great unknown is the weather and it ultimately has the greatest impact on fertiliser performance, so fingers crossed for an early spring where livestock can be turned out early and can stay out.
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