Arable advice blog

Last time I spoke about how the autumn 2023 weather affected nitrogen availability in the soil, the same can be said for sulphur.

Your risk of leaching is dependent on your soil type and over-winter rainfall but across all soil types there are still some points to remember. If you applied sulphur in the autumn, for example, as either organic manure or sulphur-containing fertiliser there is a high risk of the available sulphur leaching before spring, when the crop has its highest demand.

If you opt for a spring-applied sulphur product it’s important to apply one that is plant-available. A product that needs to be applied several weeks before it becomes plant-available could delay crop growth at this critical time, especially if soil conditions don’t allow travel. Another point to consider is that sulphur is involved in processes within crops that enable efficient use of nitrogen, therefore if the sulphur is deficient, nitrogen uptake will be reduced. This means the two nutrients should almost always be applied at the same time to ensure maximum output.

Looking at a practical point, having more than one fertiliser product to apply at your first timing in the spring means a greater number of passes, equalling increases in costs (fuel), time, carbon footprint as well as a larger storage capacity.

Overall, the simplest approach is to use an NS compound such as YaraBela Axan 27N + 9%SO3 (or an NPKS dependent on P&K requirements). This means you’re not applying all the S in one go where it is at risk of leaching, you have the increased efficiency of N and S together, the nutrients are immediately plant-available and only one pass is required. From the last 8 years of trials on compound fertilisers, applied little and often, we see an average response to sulphur of 0.79t/ha in wheat – meaning the ROI is 8:1 (using today’s fertiliser price and wheat futures).

How often can you get that kind of return on an investment these days?  

Yara commissions independently conducted field trials each year, gathering data that is relevant to improving nutrient efficiency on-farm and giving this knowledge to growers to utilise.

The 2023-24 season had particularly difficult growing conditions, as you will well know, however we can glean some useful insights in a challenging year from trial work. The optimum nitrogen rate (or N Opt) is calculated each year from the various nitrogen dose response trials we conduct. It takes into account crop and fertiliser pricing to get the optimum nitrogen rate in terms of economics and crop yield. Yara has this data stretching back 30+ years but in more recent years the N Opt has been an average of around 200 kgN/ha (feed wheat).

If we look at the trials from this year, we see that the N Opts are much higher, averaging a very high 275 kgN/ha across 6 sites (ranging from 219 – 361kg N/ha)– why is this? I don’t need to remind anyone of the awful conditions of autumn 2023, that level of excess rainfall affected the fertility of the soil by washing nutrients, normally held there, down the soil profile and therefore being lost to crops.

When we look at the untreated control plots, they yielded much lower than usual, showing that the level of nitrogen that was mineralised was less than that of an average year, as expected from unusually high levels of rainfall. The low soil N levels also affected the grain N % and protein %, with only the 300+kgN/ha plots reaching protein spec, in one case even the highest rate of 340kgN didn’t get to 13%.  

Whilst this doesn’t sound like a very positive picture, what we can do is learn from it to change the nutrition strategy, if we are faced with similar conditions in the future. Potentially saving you from being disappointed with yields or proteins when the same nutrition strategy as a normal year is used, instead of adapting it for when conditions are challenging.

Whether you drilled cereals early or plan to drill late, foliar phosphate is an efficient way of getting the nutrient into the plant to aid root growth.

Later drilled crops, in particular, don’t have as long to establish much biomass i.e. decent root systems and number of tillers, before the soils cool and the crops slow down growth for the winter. Phosphate is well-known for its role in plant root development, but isn’t plant-available once soil temperatures start to drop. It also easily gets locked up in the soil, with up to 40% of an application of MAP/DAP locked up 2 weeks after application due to becoming attached to ions (such as Al, Fe, Ca) in the soil.

A more effective method of getting phosphate into the plant, when it has a limited root system, is to apply it as a foliar spray. Foliar phosphate is taken up much more efficiently, useful for when the roots aren’t able to access soil-P, meaning that the later drilled crops can access it.

A micronutrient mixture, YaraVita Crop Boost, is a particularly useful product for application to cereals in the autumn. It not only contains P and K but also zinc and magnesium, both of which aid establishment and help reduce levels of disease infection within a plant.

Independent trial work carried out on two sites in 2021 gave an average yield increase of 1.2t/ha from an application of 3.0l/ha YaraVita Crop Boost in the autumn, followed by 2.0l/ha YaraVita Gramitrel in the spring. Another trial in 2022 showed that an application of Crop Boost at T0 followed by Gramitrel (same rates as before) gave 0.6t/ha yield increase.

Therefore, whether you can apply Crop Boost in the autumn or early in the spring at T0, there are good returns with an average yield increase of up to 0.9t/ha, making it well worth the investment.

Satellite imagery is a quick and simple way of looking at your fields, comparing biomass on different areas/soil types or picking up on potential problem areas within a field.

Establishing crops is always a tense time of year, with variable sowing conditions many crops are looking mixed across the country, especially with recent rainfall causing havoc. With plenty of things to do on farm it might not always be possible to look round all the crops as regularly as you’d like which is where Atfarm can help.

Atfarm is a web-based software and app with multiple functionalities, but one that is useful for this time of year is using the satellite images to monitor your biomass. The software uses NDVI, as well as technology that’s used within the Yara N-Sensor, to give a much more accurate scale of variation than NDVI on its own. This means you can pick up more subtle variations in-field in a quick, visual assessment. Because it is fast to carry out, it means you can regularly check the growth of the crops that are establishing and pick up on potentially problematic areas that can then be visited on-foot.

This can therefore save you time and increase efficiency as well as picking up on issues sooner, potentially enabling them to be rectified before there are large crop losses. As examples, you might see lower biomass near a wood in a crop of oilseed – does this mean that a bird scarer could be required? Or if an area within a field is showing slightly lower level of growth/colour difference, this could indicate a nutrient deficiency on a certain soil type across the field that needs addressing before if begins to affect yield.

For more information on Atfarm or other tools and services please visit www.yara.ie/crop-nutrition/farmers-toolbox/atfarm

There were different drilling strategies this year for how to best establish oilseed rape – some July drilled and some only drilled within the last week or so. This means there’s a lot of variety in growth stages across the country.

Once oilseed is at the 4-6 leaf stage there is enough leaf area present to apply some key micronutrients.  We want to ensure growth isn’t hindered at all going into the winter and micronutrients play their part in that. Oilseed can put a lot of biomass on over a short space of time if autumn conditions are right, which means there is potential for the crop to deplete micronutrient levels in the soil.

For a simple way to apply all the key micronutrients required on OSR this autumn, apply a multi-nutrient, crop-specific product such as YaraVita Brassitrel Pro. This mix contains Mg, Mn, Ca, B and Mo – vital micronutrients for this crop, particularly following autumn establishment.

Yara conducts independently run trials each year and over a 6 -year period the data has shown an average yield response of 0.3t/ha from an application of Brassitrel Pro, both in the autumn and followed up in the spring. This means it is well worth the applications as the return is several times the cost of the investment in the product.

An added benefit from making sure the crop has all the nutrients it requires in the autumn is that, anecdotally, a healthier plant is better able to cope with pest and disease pressure. Think of it as a healthy animal not being as susceptible to illnesses compared to one that doesn’t have a sufficient diet, it is similar for plants. So give your oilseed the best chance going into winter for a healthier crop come spring. 

If you remove straw then you also remove the nutrients that are contained in it, which is fine, but you need to take into account that they won’t be available to the following crop. 

Removing both grain and straw with cereal crops removes 8.0-8.5kg/t of P2O5 and 10.5-12kg/t of K2O, therefore is it important to take this into account when calculating next season’s fertiliser plan.

Post-harvest soil sampling will, of course, give a good indication of the P&K levels. If the indices are below 1 then an autumn application of P&K is justified. However, if the indices are 1 or above then autumn P&K applications are not always necessary. At those kind of levels, there will be sufficient P&K in the soil to establish cereal crops and an application of foliar phosphate, such as YaraVita Crop Boost, could be applied with a herbicide spray if required.

The real demand for phosphate comes in the spring from March to May, when a typical crop of winter wheat will require 1-2kg per day for optimum growth. Any phosphate applied in the autumn is unlikely to still be present in the soil in a plant-available form and therefore won’t be able to supply this daily demand.

Therefore, when purchasing P and K products make sure you think about the timing of application to meet the demand from the plant, otherwise you will be feeding the soil and most of the phosphate applied will have been rendered unavailable for the following spring.

For more information on different options for P & K and other nutrient solutions please visit Agronomy Advice.

Whilst harvest is underway it’s easy to forget about planning soil sampling. Post-harvest is a good time to take soil samples, before you get into drilling the next crop. UK soils have to be tested under the Farming Rules for Water, but don’t let legislation be the only reason to test your soils.

Basic soil analysis will give you P, K, Mg and pH; which is a good start but there are a lot of other important nutrients that can cause issues if deficient. A topic that’s increasingly important is that of soil health, but where do you begin?

Firstly, you need to get the basics right of course, this includes ensuring the correct pH, identifying your P and K indices and organic matter levels. On top of that, knowing the levels of micronutrients will also be useful to plan fertiliser strategies and budgets for the coming year.

By taking a broad spectrum soil sample you’ll get all this data which will help make informed decisions on-farm, but there is still an element that is missing and that’s the microorganisms that live in the soil; which are vital for a number of processes in the soil including enabling nutrient availability and breaking down material into organic matter to name a couple.

There are a few tests that can be carried out in the lab to begin to monitor your soil’s ‘health’. The Solvita Test is a test of how much respiration, and therefore ‘life’, there is in your soil. A low score shows that the soil is lacking something these microorganisms require e.g. oxygen due to lack of soil pores caused by compaction. Whereas a high score shows a good level of organisms present which improve the soil, making it more fertile. Another test is the Labile Amino Nitrogen test (SLAN) which measures the biologically associated nitrogen that is present as amino carbohydrates.

Having these results allows you to judge whether your soils are functioning in a way that enables soil biota to thrive, in turn benefiting the crops you grow.  Soil health scores can then monitor over time, showing whether they are generally improving or if specific practices are having a positive/negative effect on your soil.

There is a general consensus amongst plant physiologists that the potato crop yield is limited by the source of photosynthate as opposed to the size of the ‘sink’ i.e. the number of developing tubers following ‘tuber initiation’. It helps us consider what is important in ensuring we maximise the plant’s ability to fill the ‘tuber sink’ thus producing as many marketable potatoes as possible and improving profitability.  

In practical terms we should ensure that plants produce a full canopy of leaves as quickly as possible (rapid early emergence), this full canopy is healthy, maintaining its ‘greenness’, for the duration of the tuber bulking phase and the plant is able to translocate the sugars (sucrose) produced in the leaf down to the developing tubers as they ‘bulk’.

Nutrient deficiencies can be monitored through plant leaf analysis. Data from Yara Analytical laboratories reveals some of the key nutrient deficiencies found in potatoes to be phosphate, potassium and magnesium. Phosphate is of particular importance due to its role in the transport of the sugars from the leaf down to the ‘bulking’ tubers. The transport mechanism is an energy demanding process and the chemical energy is stored by the plant in the phosphate based molecule ‘ATP’.  Magnesium, the central component of chlorophyll (leaf greenness), clearly has an important role in keeping the leaf canopy greener for longer. Potassium helps the plant regulate water and nutrient movement from roots, through the plant, to the leaves. Water movement itself is also a necessity in the transport of sucrose down to the ‘bulking’ tubers. 

Therefore Yara’s recommendation is one application of YaraVita Magphos K at 10l/ha at tuber initiation to increase tuber number. Or two applications of YaraVita Magphos K at 5 l/ha at tuber bulking (with 14 days between applications) to increase tuber size.

With the new season nitrogen market kicked off there is the usual hurry to buy a percentage of fertiliser, but don’t rush into those decisions and end up with too much straight N.

It is well known that soil is deficient in sulphur (S), with over 90% of soils under guideline levels for most crops. This means your nutrition strategy should include sulphur additions, but what source of S should you be considering? Manures are a source of S but the amount in them is quite often lower than RB209 book values when analysed. Nutrient distribution can also be quite varied therefore over all you can’t rely solely on them to provide sufficient sulphur.

Therefore, you are likely to require some mineral fertiliser but again there are factors to consider – is the S in a plant-available form? Is the product going to spread evenly? Does the product increase the number of passes required?

Sulphur should be applied at the same time as your nitrogen applications to get the best efficiency out of both nutrients. Independent trial work shows that applying nitrate and sulphate together at each application increases yields.

Applying a quality compound product where both nutrients are in the same granule ensures an even spread pattern, where each landing site contains the correct analysis. Also, with the nutrients in the same granule it means there is no need for extra passes, saving time and money.

YaraBela Axan (27% N 9%SO3) and YaraBela Sulphan (24% N 15%SO3) are ideal products for use on a wide range of crops, consider these when fulfilling next years’ nitrogen and sulphur requirements so you don’t end up with a shed full of straight N.

Atfarm uses satellite imagery to create various maps which have different functionalities. There are the standard NDVI maps that show the variation in biomass in the field, however the range of NDVI alone is limited so there is a lower range of variation (0-9 scale). I’d recommend using the ‘optimised map’, which uses NDVI and teams it with the algorithm from the N-Sensor, to give a range of more than 25 colours - meaning a higher level of variation shown and therefore more accuracy. Another map option is the nitrogen uptake map, which gives you an approximation of the nitrogen uptake by your crop, based on the biomass and colour variation.

If you want to create a variable nitrogen rate application (VRA) map from these it is simple to do so in Atfarm. The system uses the optimised map to create the variability map and assigns different nitrogen rates to the different levels of variation. As the user, you will input your chosen fertiliser product and target rate as well as a minimum and maximum, so the system is very flexible.

Another aspect of Atfarm that will be particularly useful for taking the guesswork out of what rates of nitrogen to use on cereals is the Yara N-Tester BT. The N-Tester BT is a non-destructive handheld device that enables you to analyse how much nitrogen is in your cereal crop and then get a variety-specific recommendation. You can also link the N-Tester BT reading when choosing your target rate for the VRA map for the same field.

So overall, Atfarm enables you to put on what the crop requires and where, rather than blan-ket applications of nitrogen across whole fields. This gives a much better level of nitrogen use efficiency and in turn, better return on your investment.

In a season with excessive rainfall, ensuring optimal nitrogen levels becomes paramount for meeting premium milling wheat standards. The challenge lies in replenishing depleted soil nitrogen levels with a well-timed application.

When I look back at Yara trial data from 2020, following a wet autumn and winter, it highlights higher nitrogen rates are needed to reach those protein targets. This emphasises the importance of timing, rate and source of nitrogen application.

In order to hit the protein target millers are looking for it requires a separate application of nitrogen after the flag leaf final-dressing. This application needs to be separate to ensure the nitrogen goes towards building up the protein level within the developing grain, rather than utilising it for just yield. As well as timing, nitrogen source and rate are also important when trying to boost the protein, to ensure the nitrogen is utilised correctly in the plant.

Applying about 40-60kgN/ha (e.g. 120kg/ha of YaraBela EXTRAN) at growth stage 51 (which is the start of ear emergence) has been shown to increase grain protein levels by up to 1%. This is possible to achieve without then compromising on yield. Yara trials showed that the separate application later the in the season gave a boost in both yield and protein when applied at end of booting/start of ear emergence. For those on liquid systems, an application of foliar urea (such as Nufol 20) applied later, at milky-ripe stage, is the ideal timing for the same 40-60kgN/ha.

However, if the plant is deficient in certain micronutrients you’re less likely to have a positive impact on protein levels. Manganese and zinc, in particular, are important in the metabolism of nitrogen. If nitrogen metabolism is improved then this increases the amount of nitrogen that is incorporated into the developing protein in the grain. Trials work, again, has shown that an application of zinc at T2 timing can increase grain protein by up to 1.4%! Therefore it is important to ensure there’s no zinc deficiency if aiming for the milling premium - an application of YaraVita Mancozin or YaraVita Zintrac will help prevent this.

Due to excessive rainfall this season, soil N levels were potentially depleted when compared to a more typical year. With the premiums available on milling wheat this year you might be aiming for protein spec, if so the rate and timing of nitrogen is key.

 If I look back at Yara trial data from 2020 (following a wet autumn/winter), only the crops with higher N rates reached target proteins, due to the depletion of soil N. In order to hit the protein target millers are looking for it requires a separate application of nitrogen after the flag leaf final-dressing.

The application needs to be separate to ensure the nitrogen goes towards building up the protein level within the developing grain, rather than utilising it for just yield. As well as timing, nitrogen source and rate are also important when trying to boost the protein, to ensure the nitrogen is utilised correctly in the plant.

1) the number of ears per square metre, 2) the number of grains per ear, and 3) the size of the grain. All of these can be influences by crop nutrition choices.

The numbers of ears is driven first and foremost by drilling the correct seed rate and having good seedbed conditions to maximise establishment. Early applications of NPKS fertiliser can also help with manipulating tiller numbers. As can conventional practices like rolling

Crops are varied in this growth stages. Those early drilled crops at GS30 (the traditional T0 timing) and those later drilled crops, or second cereals still tillering. Therefore there are two different foliar nutrition strategies to consider.

For the more advanced crop, the number of ears is set. Focus now turns to maximising number of grains per ear. This is where the micronutrients boron, copper and zinc can have a big impact. The time to have an impact is when the ear is being formed (GS30-32). Alongside is the need to maximise photosynthesis to ensure the crop has a healthy plant structure. Both magnesium and manganese play a key role.

YaraVita Gramitrel was developed specifically for the cereal crop. It contains all the above nutrients in an easy to use formulation. A fully replicated trials programme conducted over 6 years (2016 - 2021) showed 2.0 lt/ha applied in the spring between growth stage 30 and 32, delivered an average yield increase of 0.55 t/ha.

In practical terms when should I apply the product? This should be driven by the growth stage and biomass of the crop. For the advanced crops then T0 would work, where you have more leaf than soil. For backward crops then allowing them time to achieve more growth would be wise, then include the Gramitrel at T1.

A proactive approach to nutrition is better than cure and generally more cost effective, however there needs to be sufficient foliage to optimise the product.

With good establishment conditions and mild weather in the autumn, cereal crops are looking good. There is a lot of good, above-ground growth but with recent rainfall in some areas waterlogging will have affected the root system.

Waterlogging has a massive effect on the roots, causing them to lose a significant amount of mass if sustained waterlogging persists. The predicament that this leaves us with is a lot of above-ground growth without the below-ground growth to sustain it; when it comes to spring, the root system won’t be able to provide enough nutrients to the leaves.

But there is a way that we can repair some of the damage from waterlogging and increase the root growth in the spring to ensure that growth isn’t compromised.

Phosphate is a key nutrient for root growth, however getting into the plant, when it has a limited root system, isn’t straightforward. Foliar phosphate uptake is much more efficient when the roots aren’t able to access soil-P, meaning that crops can access it easily.

A micronutrient mixture YaraVita Crop Boost is a particularly useful product for application to cereals in the autumn or at T0. It not only contains P and K but also zinc and magnesium, both of which aid establishment and help reduce levels of disease infection within a plant.

When this is combined with an NPKS compound fertiliser at the first nitrogen timing, such as YaraMila 52S, the crop is getting the best of both sources of phosphate for increasing those lost roots.

For more information please visit Agronomy Advice.