Grass mineral analysis – a useful management tool

12 June 2021

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 grassland to utilise silage mineral analysis to improve yields and nutrient use efficiency.

During the winter a farmer asked me to have a look at his 1st cut silage mineral analysis report received back from the Yara Analytical Services lab which highlighted a couple of potential problems. Because it was a composite sample from a number of different fields, it warranted a closer look in the spring, so three silage fields were sampled in May, 10 days before harvest.

The three fields had received the same nutrients in the spring - a combination of slurry and YaraMila EXTRAGRASS (27-5-5+6%SO3). Nitrogen, phosphorus, 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 deficient.

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 low soil pH (5.4) was the difference in the ‘deficient’ field. This makes sense, as soil pH affects nutrient availability. This again highlights the benefit of analysis and in particular the importance of acting on the results, especially correcting low soil pH.

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Nitrogen – what is the rule for grazing?

8 June 2021

As a rule of thumb we use the two units of nitrogen per day to guide nitrogen application rates for grass silage swards, but what about grazing? Where there is a high demand for grass on intensively stocked farms, then we should be aiming to apply 1 unit of nitrogen per day, over the coming three months. So, if your rotation length is 21 days, then apply 21 units of nitrogen, and aim for a total of 30-31 units of nitrogen per month. If this seems low, remember there is nitrogen carryover from urine and dung from previous grazings.

For best results, use a nitrate-based nitrogen fertiliser, like YaraBela Nutri Booster. This CAN-based fertiliser with 5 % sulphur was specifically formulated for mid-season nitrogen applications. Nitrate based fertilisers are more reliable during the summer months. The added environmental benefit of using CAN based nitrogen products like YaraBela Nutri Booster is its very low ammonia emissions - even during the summer months.

If paddocks have a clover content of 20 – 25 %, then there is scope to stop nitrogen applications altogether from June onwards. Irish research has demonstrated that clover swards receiving 120 units/acre of nitrogen annually, had similar performance to perennial ryegrass swards receiving 200 units/acre. 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 and K compound like Yara Super PK throughout the growing season are necessary for high levels of clover productivity and biological N fixation.

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Fertilising second cut silage

18 May 2021

It’s fair to say, that first cut silage yields have been disappointing. It’s no wonder considering the growth we’ve had during April and early May. Some have ended up grazing fields that were intended for 1st cut, so with this in mind and low silage stocks, a good second cut will be more important than ever to put tonnes in the pit for the winter ahead.

If adequately fertilised, and with favourable growing conditions these second cuts crops are capable of 6 – 7 tonnes of fresh weight per acre, which isn’t far behind a good first cut. Slurry and fertiliser application rates are important considerations to make the most of second cut yield potential.

It’s best practice to apply fertiliser a week after the slurry has been applied. If no slurry is being applied, then spread the fertiliser within a couple of days of the 1st cut harvest or on closing-up from grazing. It happens regularly that nutrients applications are delayed too long, which then results in lighter crops or crops needing a longer growing period, which in turn lowers silage quality.

Sulphur is an important nutrient, and it certainly merits using a fertiliser that contains sulphur on these second cuts. The response does vary according to soil type, regularity of manure applications and overwinter rainfall, but the majority of silage crops do respond to applications.
With over 90 % of silage samples analysed having very low selenium levels, there is also an opportunity to increase the selenium content of silage for the winter ahead by using fertiliser’s fortified with selenium like YaraMila SILAGE BOOSTER or YaraBela NUTRI-BOOSTER. This is most beneficial to pregnant cows and ewes.

Yara second cut fertiliser recommendation on fields with good soil fertility

No slurry -                                           4 bags/acre of YaraMila SILAGE BOOSTER

1,000 gal/acre cattle slurry -             3¾ bags/acre of YaraMila SILAGE BOOSTER

2,000 gal/acre cattle slurry -             3 bags/acre of YaraBela NUTRI BOOSTER

Remember, P fertiliser rates may need to be adjusted based on the nitrates (NAP, 2017) limits for your farm. With the weather Gods on our side, a good second cut has the scope to make up for lighter first cut crops, but it’s important to order what fertiliser is required and have it ready for spreading.

Read more about grass silage nutrition

Second cut silage fertiliser recommendations

Second cut silage fertiliser recommendations
Philip Cosgrave, Yara's Grassland Agronomist recommendations for second cut silage fertiliser.

Slurry for second cut silage

18 May 2021

If slurry is available, the amount needs to be evenly applied over the entire second cut area. What often happens is, too much is applied at the beginning before it’s realised there’s not enough in the tank, and then the application rates have to be reduced or even vice versa. We end up with parts of the field being undersupplied with nitrogen (N) and potassium (K).

Slurry needs to be applied as soon as the first cut has been harvested, and preferably by low emission spreading systems (LESS) like trailing shoe. On fields that are only now being closed up for silage after being grazed, then the grass needs to be well grazed down. Slurry is a great source of nutrients and reduces fertiliser costs, however, we don’t want the residues of this slurry ending up in the pit and causing issues. It really depends on how ‘watery’ or ‘thick’ the slurry is. Thick slurry would need to be applied in lower volumes for fear it mats the grass and doesn’t get washed off. Lower dry matter (DM) slurry or ‘watery’ slurry can be spread at higher rates.

The period of time between slurry application and a planned harvest will also dictate the slurry rate. If it’s less than 6 weeks then low volumes, and if it’s ‘thick’ slurry being spread by splash plate, then it might be better not to apply, and leave till later in the season.

Read more about grass silage nutrition

Reach that maize yield potential with foliar nutrition

06 May 2021

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.

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Cold and dry April hits grass growth rates

30 April 2021

It’s likely that 1st cuts will be lighter, so if you’re looking to cut high-quality silage stick as close to your planned cutting date. Hopefully, we can make up this yield loss in subsequent cuts, but we won’t be able to make up for the higher costs of supplementing poorer quality silage.

On farms where 1st cuts are only being closed up, then use a nitrate-based fertiliser. If slurry hasn’t been applied then definitely go with an NPKS product like YaraMila Silage Booster to maximise silage yields. Potash (K) is a really important nutrient for silage and a low K supply can really hit silage yields. For every kg of K we apply per ha, we see a return of 20 – 30 kg of silage. If 22 – 33 m3/ha (2,000 – 3,000 gallons/acre) of cattle slurry is applied, then an N + S product like YaraBela Nutri Booster is adequate.

To calculate the N required for a 1st cut that is only being closed-up for silage, then count the days between closing-up and a planned cutting date. Subtract 5 days from this number, and then multiply by 2.5 to give the kg/ha of N required (multiply by 2 to give units/acre). The N in any cattle slurry (0.9 kg/m3 or 8 unit/1,000 gal), along with 20 % of any fertiliser N applied earlier for grazing, should be deducted from the N requirement of the silage crop to give the fertiliser N rate.

Read more about managing second cut silage

Four steps to successful reseeding

09 April 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.

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Grassland agronomy advice

The latest grassland fertilser and nutrition advice from the Yara agronomists.

Purchase quality compound fertiliser

02 April 2021

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 Extragrass (27-2.2-4.2+2.4+%S) with a blended 27-2-4+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, 4.2% K and 2.4% S. 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 Extragrass, there was a yield loss of nearly 400kg/ha of grass dry matter. That’s a loss of nearly 1.5 tonnes of silage, worth around €30 per ha.

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

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The first cut is the cheapest

11 March 2021

With 1st cut fertiliser applications underway, it’s important to remember that 1st cut silage is the most economical cut to grow. For all cuts the variable costs are similar. Due to the high yield of the 1st cut, it is this forage that achieves a lower cost/tonne of dry matter ensiled. The nutrition given to these crops this spring will be the main driver of how well they perform come harvest.

What nutrients are required? Slurry is available on most farms and should preferably be applied by low emission equipment. It minimises nitrogen (N) losses from ammonia volatilisation, leaving more N in the soil for the crop. 1,000 gallons/acre of cattle slurry, contributes 7 units of N if applied by splash plate (or 9.5 units if applied by trailing shoe/trailing hose). After accounting for the N in the slurry, the mineral N rate should be calculated to ensure that the crop receives a total N rate of 100 units/acre.

At least 70 units of potash should be applied for 1st cut, unless the soil index is 3 or above. A little more can be applied if the soil index is 0 or 1. If this potash rate is not supplied via slurry then apply in fertiliser. 1,000 gallons/acre of cattle slurry contains 21 units of potash. All 1st cut silage crops should routinely receive 25 – 30 units of sulphur. Where an NPKS fertiliser is required, then YaraMila Silage Booster ticks all the boxes.

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The big questions this spring

26 February 2021

How long should I leave between applications of fertiliser nitrogen (N) and slurry?, is one of the questions I am most often asked. Slurry applied on fertiliser N creates ideal conditions for denitrification, i.e., anaerobic conditions and high carbon compounds. It is recommended to leave 7 days before or after slurry spreading for application. There’s always some confusion around lime applications and urea. If lime is applied, then urea shouldn’t be spread for at least 3 months afterwards. The lime increases the soil pH which increases the rate of volatilisation of ammonia. Lime can be spread 10 days after urea applications.

I’m also asked: What are the sulphur levels in slurry and are they enough for a 1st cut silage? If 2,000 gallons/acre of cattle slurry (22 m3/ha) was applied this spring, it’s estimated to contain 6 units/acre (7 kg/ha) of crop available sulphur. This is not enough, as a decent 1st cut will remove 28 - 32 units/acre (35 – 40 kg/ha). Sulphur in autumn slurry applications may be lost via overwinter leaching. Some of the available crop sulphur (sulphate) in slurry is also lost during storage, as anaerobic storage conditions lead to the conversion of sulphate to hydrogen sulphide gas.

Phosphate is another topic. The 16 units/acre (20 kg/ha) of phosphate on my grazing area, when should I apply? My advice is to spread it over two or three applications, with two preferably in the spring and then another in early June.

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Lime your grassland and reduce your greenhouse gas emissions

12 February 2021

Research in Ireland has shown that by liming to increasing soil pH there also followed a significant reduction of N2O emissions and increased grassland productivity. Liming is well known as an agronomic measure to ameliorate acidic soils and maintain soil pH at the optimum level for high crop productivity. Liming increases the activity of soil microbes and the availability of nutrients, most notably phosphate, leading to improved plant growth. This research could be used to further support an increase in the optimum soil pH for grassland on farms with high grass yields.

The soil at the trial site was classified as acidic, with a pH of 5, but liming over 10 years resulted in soil pH ranging from 5.0 to 6.9. Increasing soil pH by liming resulted in a significant reduction of N2O emissions and increased grassland productivity compared to the un-limed plots under the same management and nitrogen fertiliser regime. The degree of reduction in N2O emissions mainly depended on the amount of lime applied across the experimental period. When soil pH was increased to 6.9, N2O emissions were reduced by 39% compared to the control soil pH of 5.0. The long-term results in terms of grass yield showed that the highest yields were achieved when liming was combined with regular phosphate application. Plots limed to pH higher than 6 had 0.5 t/ha higher dry-matter yields, while the yields in limed plots with optimal P content had 1.5 t/ha higher yields on average compared to un-limed soils with low P fertility.

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Spring N for grazing - what’s your plan?

12 January 2021

One of the most important factors affecting spring grass growth on farms is the timing and quantity of the first spring nitrogen (N) fertiliser application. Early spring grass for grazing is extremely valuable. Therefore however modest any increase in grass growth might be, it can be a big help to balance the overall feed requirement of livestock. Grass requires more N to grow, so sulphur (and potentially phosphate and potash) are also required.  

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. If you’re using a soil thermometer for the first time, my advice is it make sure you insert it 10 cm’s into the ground. You can also check the Met Eireann website for soil temperatures. Of course, a favourable weather forecast and good field conditions are also necessary when deciding when to spread.

For your first N application, we recommend using a product with sulphur such as YaraBela Nutri Booster at a rate of 20 - 23 units N/acre. The second application should aim to deliver 40 - 45 units and be timed to take advantage of improving growing conditions in early April. These rates are appropriate for newer swards with high perennial ryegrass content. On less intensively stocked farms or on swards which will be less responsive to N, then the above rates should be scaled back by 25%.

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Soil health is vital: Test it, review it and take action

10 December 2020

At some stage, over the next couple of months, you should 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 2021. An NMP is really about prioritising how we 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 1 – 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 farm is regularly soil testing, say every three years, then the €1 ha/year cost is money well spent.

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3-cut vs 4-cut Silage System: Does it make a difference?

27 November 2020

The quality of grass silage fed to dairy cows is an important factor in cow performance and margin-over-feed cost. Silage digestibility (D-value) declines by an average of 3.3% for each week delay in harvest. Hence the move by dairy farmers to cut earlier and more frequently. A recent Northern Irish study examined cow performance and the whole system impact of offering silages produced within either a 3 or 4-cut system.

Total silage dry matter (DM) yields for the 3 and 4-cut system 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 system respectively.

Cows on the 4-cut system had higher silage intakes (+9.5%), produced more milk (+6.4%) with higher milk protein (+2.1%) but slightly lower fat content (-2.4%). Silage production costs were calculated as €126 and €149 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 were 25 cents/cow/day higher with the 4-cut system, but the value of milk produced was 78 cents/cow/day higher. The margin-over-feed cost was 53 cents/cow/day higher for the 4-cut system. For a 100 cow herd over a 180 day winter period, the 4-cut system resulted in a €9,549 increase in margin-over-feed costs.

Multi-cut silage systems may not suit every farm, but bring the potential to lower feed costs, improve milk output and make dairy farms more self-reliant.

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Green Ammonia – What is it and Why?

27 November 2020

Yara announced its plan to produce Green Ammonia earlier in the year but what does this actually mean?

In order to produce ammonium nitrate (AN) fertilisers, ammonia is mixed with nitric acid to produce a liquid ammonium nitrate solution, this then goes on to produce the prills or granules that you’d recognise as fertiliser. The ammonia that is used for this process is produced with hydrogen gas from fossil fuels, mainly natural gas (methane), and therefore is classed as ‘brown’ ammonia due to its use of natural resources.

Green Ammonia is produced in a different way. H2O undergoes electrolysis, which is powered by renewable energy sources such as wind and solar power, in order to get the required hydrogen gas. Nitrogen is obtained from the atmosphere (which is 78% nitrogen gas) and two undergo the Haber-Bosch process. The end result is Green Ammonia, made from renewable sources. Unlike in the traditional ‘brown’ ammonia method, there is zero CO2 ‘waste’, therefore there is only a very low carbon footprint associated with Green Ammonia.

This is increasingly important as consumers want to know the carbon footprint of their purchases and it is thought that all food items will show a carbon footprint value in the near future. Every process needs to be sustainable and have as little impact on climate change as possible. With ammonia being the second-most-widely produced commodity chemical globally, (annual production volume of over 180 million tonnes) this new method would make a massive impact worldwide.

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Grass YEN 2020 results review

13 November 2020

Grass YEN, the industry-science platform had its end of year meeting earlier in October. Yara was once again co-sponsor of the event, and I would like to take this opportunity to thank the five farmers that we sponsored for their time and energy in participating in this year’s competition.

There were 23 silage crops entered in this year’s competition. The yield gap between 1st cuts and 2nd cuts was narrower as you would expect with the drought affecting 1st cut yields. Average 1st cut dry matter (DM) yields were 5,385 kg/ha, ranging from 3,502 – 9,014 kg/ha. Average 2nd cut DM yields were 4,602 kg/ha, and ranged from 3,218 – 8,754 kg/ha. DM yields for 3rd cuts averaged 3,028 kg/ha.

Nutrient offtakes is always an interesting aspect of Grass YEN, where grass samples from each grass crop are analysed for their mineral content and from this offtakes are calculated. The average offtakes for each tonne of DM yield across all crops was 21kg of N, 3kg of P, 28kg of K and 2kg of S. With the highest yielding cuts taking off over 300kg N/ha, >330kg/ha K, >20kg/ha S.

Looking at the tissue concentrations of the crops sampled, 74% of the crops were considered sulphur deficient. If we want to improve nutrient use efficiency on farms, the use and rate of sulphur applications on silage crops needs careful consideration and could be an easy win to reduce nutrient loses, increase yields and improve silage quality.

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.

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