Philip Cosgrave

Grow Your Grass with Philip Cosgrave

Keep up to date with all the latest grassland agronomy advice with this regular column from Yara's chief grassland agronomist Philip Cosgrave.

In the battle to reduce our carbon footprint, could green ammonia be the hero?

01 October 2020

Ammonia is a gas that is widely used to make nitrogen fertilisers. Green ammonia production is where the process of making ammonia is 100% renewable and carbon-free. One way of making green ammonia is by using hydrogen from water electrolysis and nitrogen separated from the air. These are then fed into the Haber process (also known as Haber-Bosch), all powered by sustainable electricity. In the Haber process, hydrogen and nitrogen are reacted together at high temperatures and pressures to produce ammonia (NH3).

Reducing the amount of carbon dioxide produced during the ammonia manufacturing process is critical to achieving net-zero targets by 2050. The best way to reduce carbon emissions when making ammonia is to use low-carbon hydrogen. Green hydrogen is produced using water electrolysis to generate hydrogen and oxygen, and the availability of sufficient green energy limits the production capacity of green hydrogen.

A consequence of decarbonised ammonia production is you can’t produce urea. Because urea is made by combining ammonia and the carbon dioxide (CO2) released in the earlier process where hydrogen is split from the carbon source (usually natural gas) to provide the hydrogen in ammonia (NH3) production. So it’s unlikely urea can be part of a decarbonised food chain.

It’s Yara’s goal to decarbonise fertiliser production, but it will require significant ongoing investment in R & D and production capacity. It’s interesting to note that when Yara first began producing nitrogen fertiliser in Norway, back in 1905, the process was carbon-free! The energy source back then was hydro-electricity.

Nitrogen: to spread or not to spread?

04 September 2020

Spreading nitrogen (N) from mid-September onwards needs careful consideration. The growth response will have to justify the cost, and excess or unused soil nitrate should be minimised as we approach winter as it constitutes a risk to water quality. If you’re farming in an NVZ, then you’re allowed up to 80 kg/ha of mineral nitrogen on grassland between the 15th September and the 31st October, with a maximum of 40 kg/ha of N being allowed in any one application.

Preferably N applications should take place at a time when grass growth is sufficient to utilise it. Teagasc research on autumn applied N has shown that 30 kg/ha of N applied on the 1st of August, 1st September and 1st of October gave a grass dry matter (DM) response of 27 kg, 19 kg and 10 kg respectively, for each kg of N applied. If we assume that this grass DM contains 3% N, then our apparent N recovery rate was 80% for August, dropping to 30% for October.

It is important that any N applications take into account the requirement for grass, but don’t forget to also consider your soil and weather. I advise taking a paddock by paddock approach to spreading N rather than blanket spreading the entire grassland area. Depending on your demand for grass, apply from 20 – 25 kg N/ha, and preferably by mid-September. Higher rates of N, or N applied in October, won’t be justified in most years.

Read more on grassland nutrition

 

Fertiliser advice for short term leys and hybrid brassicas

14 August 2020

Adequate fertiliser is essential to obtain the maximum yields that short term leys and hybrid brassicas are capable of producing. In general these crops are being sown after a cereal crop, and therefore soil nitrogen supply (SNS) is likely to be low.

With temporary leys following cereals Yara recommend up to 50 kg/ha of nitrogen, 20 kg/ha of phosphate (P) and 40 kg/ha of potassium (K) applied at drilling. The phosphate in particular is important for root development and tillering. YaraMila Actyva S (16-6.6-12.4 + 2.6% S) contains ‘P-Extend’ which will provide a consistent and reliable supply of phosphate for the remainder of the growing period. Not forgetting that these fast growing grass leys have a requirement for sulphur which is often forgotten.

Remember that there’s 7.5 kg/ha of nitrogen in every 1 cm of grass growth. We would expect Italian ryegrass or Westerwolds to grow to a minimum height of 10 cm by the end of October, therefore requiring 75 kg of N. If we apply 50 kg of N from the bag, there will be enough soil residual N to provide the remaining.

The hybrid brassicas such as Redstart and Interval may still be drilled into late August and they have similar nutrient requirements to that of forage rape and stubble turnips. We recommend up to 80 kg/ha of nitrogen, 10 kg/ha of phosphate (P), 40 kg/ha of potassium (K) and 12 kg/ha of sulphur (S). A perfect fit for these nutrient requirements is YaraMila Silage Booster (20-2-12 + 3% S +Se) with ‘P-Extend’.

It is vital to get these crops off to a good start, so placing the fertiliser in the seedbed will help to establish strong healthy plants.

Read more on fertilising short term leys

 

Latest grassland video advice

Grow grass now to extend your autumn grazing

31 July 2020

From mid-September daily grass growth will fall rapidly. After this point grass can quickly run out and either livestock performance declines or they will require housing to maintain performance. If we start to manage grass now, we can grow more grass over the coming weeks. This then allows us to build up a bank of grass for extending the grazing period and, if correctly managed, allows for earlier turnout of livestock in the spring.

Grass grown now will remain leafy, albeit not as good as leafy grass grown earlier in the year. It will not require the same level of purchased feed to maintain a certain level of milk yield, or daily liveweight gain, compared to feeding poorer quality forage indoors or set stocked grazing where there is poorer quality grass with lots of dead material at the base.

Grass yield response to autumn applied nitrogen

If we optimise grass growth over the coming weeks by applying nitrogen and sulphur now and operating a rotational grazing system (even if it’s temporary fencing) then we can save money and shorten the indoor period. This means that livestock will need to graze an area and then be moved onto a fresh area every 1-4 days, allowing the sward to recover and start growing again. The drier or ‘earlier’ parts of the farm should be grazed from mid-September and then closed off as the regrowth on these parts can be carried over the winter months for grazing first in the spring.

Read more grassland fertiliser advice

Soil fertility in grass based systems

17 July 2020

Adopting Controlled Traffic Farming (CTF) could help reduce soil compaction risk and boost yields by up to 10.5%, while also reducing nitrous oxide emissions.

In Yara’s recent grassland webinar, we were joined by Mark Plunkett, a specialist in soil and plant nutrition with Teagasc in Ireland. Mark reviewed current soil fertility trends on Irish farms. He then went on to explain why Teagasc have focused considerable effort to demonstrate why it’s worth improving soil pH, phosphate (P) and potash (K) levels to keep farms competitive.

On Irish dairy farms the trend over the last 10 years has been positive for soil fertility. This information is collated annually from Irish soil test result records. Soil pH has improved on these farms, and currently 59% of soil samples have a pH of 6.2 or above, up from 25%, 10 years ago. The optimum soil pH for grassland in Ireland is 6.2 – 6.5. Half of soil samples currently tested are at the optimum or higher for P, and 59% were at the optimum or higher for K. Crucially, the number of soil samples at the optimum or higher for pH, P and K has doubled in the last 10 years. It now stands at 21%.

Did you know up to 15% of nitrogen can be wasted if soil P is below par? As Mark discussed, using research and on-farm data demonstrates the importance of optimising soil fertility, to grow more grass cheaply and sustainably. Mark signed off with some very simple advice: soil sample regularly and follow a fertiliser plan.

Listen to the grassland fertility webinar

Controlled traffic farming

23 June 2020

Adopting Controlled Traffic Farming (CTF) could help reduce soil compaction risk and boost yields by up to 10.5%, while also reducing nitrous oxide emissions.

Limiting compaction at silage-making

Grassland farmers could benefit from adopting an ‘arable mindset’ and controlling the movements of machinery across fields as a means of limiting compaction and maximising grass yields.
This is according to Dr Paul Hargreaves, grassland researcher for SRUC, who has just completed a three-year study looking at CTF on silage ground. His results show grassland farmers could expect a yield increase of 8.5-10.5% by following a CTF system, while nitrogen use efficiency will also be improved.

Rather than driving anywhere on a field, CTF means machines follow set wheel marks which run parallel to the line of trajection and then around the headland. “It’s about trying to control the movements of machinery around a field to limit the area they cover and running all machinery along similar wheelings. It’s trying to think of grass as an arable crop,” says Dr Hargreaves. SRUC trial work found that about 83% of a field cut three times using a forage harvester, with slurry applied, will be covered in wheelings on a traditional system. These wheelings will suffer from soil compaction and therefore reduced yields. On a CTF system, the area covered in wheelings will reduce to about 19%.

SRUC trial results

The three-year trial at SRUC looked at long-term performance of a perennial ryegrass and red clover ley, which was established at the start of the trial. They looked at different nitrogen application rates and compared CTF and non-CTF. In the non-CTF strips, machinery was driven wherever they wanted. On the CTF strips, the fertiliser and slurry spreaders, mower, tedder, rake and forager, all followed a nine-metre working width.

Dr Hargreaves was keen to see the damage caused to the wheelings on the CTF system over the three years. Although there was an increase in soil bulk density and reduced porosity, he says there was ‘limited damage’ and no issues with water run-off from these areas.
“So far, we’ve seen a reduction in yield on those wheelings and the red clover has disappeared entirely, but the perennial ryegrass is still there,” he says.

He believes this is not a huge issue on a three-year red clover ley as the issue could be addressed as part of reseeding. If a farm was doing CTF on a five to six-year perennial ryegrass and red clover ley, some kind of mitigation work would be needed on these wheelings, such as sward lifting. Wheelings would then need to be shifted across in the next season so improvement work was not compromised.

Overall, Dr Hargreaves says focusing traffic in set areas helps minimise overall field damage.

“You are reducing the structural damage to soils so you are potentially maintaining drainage and the quality of the soil. And you know where the damage is on the field so you can deal with it specifically,” he says.

Why is compaction a problem?

  • Limiting soil compaction should form part of an holistic approach to soil management which should also look at pH and maintaining key nutrients such as potash and phosphate. There are some key reasons why compaction should be avoided:
    Prevents water infiltration – resulting in wet soils which take longer to drain.
  • Reduces soil pore spaces – so earth worms can’t do their job. Oxygen needs to get into the soils and carbon dioxide needs to escape. This is compromised if soils are compacted.
  • Reduces nitrogen utilisation – anaerobic soils will reduce the mineralisation of key nutrients such as nitrogen.
  • Increases nitrous oxide production (a greenhouse gas) – this gas is a product of denitrification, a biological process by which some nitrate in the soil is reduced to nitrous oxide. The rate of denitrification is increased in compacted soils, because of the lack of air as they’re denser and wetter for longer.
  • Reduces nutrient availability – such as phosphate.

Operating Controlled Traffic Farming

To operate CTF, Dr Hargreaves suggests thinking about the following:

What is the smallest working width of all your machinery?

If your smallest working width is nine metres, all equipment needs to work within this. This includes the slurry spreader, tedder and mower, etc. This means machinery will have to work along three-metre-wide tyre tracks in the field.

Split up fields

Divide the width of each field by the working width of your machinery. If a field is 135 metres wide and your smallest working width is nine, split it into 15 lines. If you end up travelling more on certain areas of the field, make a note of it and target soil improvement work in this area.

Use technology

Dr Hargreaves believes GPS and auto-steering technology is essential to do CTF properly. However, as a minimum he thinks GPS is essential. This will increase accuracy.
“Newer tractors being sold and equipment used by contractors often have GPS. This technology is becoming increasingly common place so it could be a case of just using the technology you’ve already got,” he says.

Use marker posts

If technology is not an option, consider using sight posts or positions in the field so machinery is driven in a particular route. All individual tractor drivers will need to pay care and attention.

Pay attention during carting

The distance between the forage harvester and silage trailers will increase with CTF – potentially to
six metres. This means the team will have to work steadily. Also, consider using high-sided trailers and not filling trailers all the way to the top.

Read more on the benefits of CTF

Keep the pedal to the metal

22 June 2020

With 1st cuts at below average, particularly those cut in the latter half of May, and very slow 2nd cut regrowth, we may be feeling slightly nervy when looking at our silage pits. Grass growth rates according to PastureBase are well back on last year as a result of the drought, so we’ll need some good growth in the months ahead to build up silage stocks. The rain has helped lower soil moisture deficits, but they’re still restricting grass growth.

On intensive grazing farms where growth rates have responded to rain, maintaining a 21 day rotation and keeping residuals of 4 cm is crucial. If paddocks have gone stemmy, pre-mow to get them back on track, alternatively target these for silage. Heavy covers of > 1,500 kg should be cut as surplus bales, and maintain grass growth by keeping N + S applications up-to-date. Slurry should be applied where silage/surplus bales are taken off. Remember to keep ammonia emissions as low as possible by using low emission spreading equipment such as trailing shoe. If slurry is not available, then apply a NPKS quality compound fertiliser such as YaraMila Silage Booster to replace P and high K off-take from taking surplus bales.

For N applications on a 21 day grazing rotation, 1 – 1.2 units N/acre/day is sufficient. Between the release of mineralised N from soil organic matter following the rain, together with residual N from fertiliser applications that hadn’t been used by the grass due to the drought, means there’s quite a large pool of nitrate available in the soil to meet the demands of increased growth rates. So, no benefit in over applying N.

With 1st cuts below par and 2nd cuts delayed, it might be prudent to look for alternative ways to put tonnes of silage in the pit. Buying standing crops of spring barley for wholecrop for instance could be an option. Preliminary DAFM statistics show an increase of 110,000 acres of spring barley in the country this year. Alternatively, drill a forage brassica crop into stubble for grazing in the Autumn and Winter by youngstock.

Knowing how unpredictable our weather is, it’s better to have than be without!

Read more on increasing grassland yield

Hot topics: New season nitrogen, boosting maize and cow health

08 June 2020

New season nitrogen – do your research

Whether it’s new season or this season’s nitrogen requirements you might be considering to purchase, don’t end up with fertiliser that’s not fit for purpose. This can mean a wrong grade or choosing a product that looks good on price but doesn’t have the spreading quality characteristics. The wrong grade could mean purchasing straight nitrogen instead of nitrogen and sulphur. For quality, some nitrogen products look good but flatter to deceive as the granules look big but they’re soft, so shatter easily on the vanes of the spreader. So, caveat emptor!

Read more on nitrogen and sulphur

A nutritional boost for maize

Maize crops are at an important stage right now and nutrition is really important for these crops as they undergo rapid growth and development. With the weather we’ve had, these crops need all the help they can get.
A foliar feed would be beneficial, either as a standalone application or in conjunction with a planned herbicide. YaraVita MAIZE BOOST is specifically formulated for foliar applications on maize and contains magnesium and zinc, the two most widespread nutritional deficiencies seen in maize. It also contains phosphate and potash, which may be limited in these dry soil conditions.

Read more on forage maize nutrition

Heathy grass for a healthy herd

Finally, keep up with P & K applications for grazing. The phosphate keeps levels in grazed grass topped up, which is particularly important in dairy herds. While potash applications where necessary, will help drought tolerance. Use a compound NPKS product like YaraMila SUPERBOOSTER (25-2.2-4.2+2% S+Se), which provides the full gambit of nutrients to grow more grass this summer.

Read more on the benefits of selenium

Reach that maize yield potential with foliar nutrition

05 May 2020

Maize has a high demand for nutrients due to its high yield potential. 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. Magnesium is essential for the early establishment of the plant. A deficiency is reflected in reduced crop yield at harvest.

Phosphorus and potash are primary nutrients, however many soils have not got 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. 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 MAIZE 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.

Read more on forage maize nutrition

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Four steps to successful reseeding

24 June 2020

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.

benefit of reseeding on net profit

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 % in weed ground cover.

Step 3: Take a soil test and act on the results. Before you start, be sure to complete this step. 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 DAFM Grass and White Clover Recommended List and pick those that suit your particular farm.

Step 4: Provide new swards with the correct nutrients at sowing. Failure to do so will hinder the success of the ley. Where the soil P & K index is 3, then use 2.5 bags/acre of YaraMila MULTI-CROP (8-10-20 + 2% S) at establishment. New leys have a greater requirement for phosphate to help with root development, and a lower requirement for nitrogen. It is recommended to apply more nitrogen after establishment, but this needs to be assessed carefully as reseeds established in August by ploughing or deep cultivation will release considerable amounts of N from the microbial breakdown of organic matter, called mineralisation. This mineralised N is available for the reseed, providing adequate N for the remainder of the growing season. Where swards have been established through minimal cultivation or direct seeding, these may require a bag/acre of YaraBela AXAN or YaraBela NUTRI-BOOSTER before the 15th of September.

My Top Tips: Weeks 4-6 (post-emergence) apply herbicide to prevent weeds competing for nutrients and space. Graze lightly with youngstock or sheep, as soon as the new plants don’t pull out of the ground, which is usually when grass height is at 6 - 7 cm or at the two leaf stage to promote new shoots, and thus the long term productivity of your new sward.

See our new sown grass fertiliser programme

Purchase quality compound fertiliser - it pays every time

04 April 2020

At this stage, most 1st cut fertiliser applications are completed, but are you confident that your target fertiliser rate was evenly applied? Yara has demonstrated how, over 24 metres, the physical quality of a fertiliser influences the yield and quality of a grass crop.

Yara has looked at this effect by comparing YaraMila Extra Grass (27-2.2-4.2+S) with a blended 27-2.2-4.2+S. The target rate for both products was 500kg/ha and the spreader settings were changed for each product on testing. The YaraMila product achieved the target rate across the whole bout width; however the application rate for the blended product varied between 400 to 648kg/ha.

We then analysed separately each of the 23 trays from the blended product, to determine the actual NPK+S content. Because the YaraMila product is a compound, we know that the product in each tray contained 27% N, 2.2% P and 4.2% K. The blended product had a variation in N across the bout width of between 91kg and 160kg, for P the variation was 10 to 19kg and for the K it was 34 – 59kg/ha. The target was 135kg, 25kg and 25kg for N, P and K respectively. Accounting only for unevenness of the N, in this blend, compared to the YaraMila Extra Grass, there was a yield loss of nearly 400kg/ha of grass dry matter as a result of the poor spreading pattern of the N. This equates to 1.5 tonnes/ha of silage which, based on barley and rapeseed meal, would have a replacement value of €61.

Don’t take the chance, use a quality compound fertiliser

Read more on YaraMila compound fertiliser