Arable advice blog

Ensuring adequate nutrition of oilseed rape crops is vital to maximise yield and profitability 

There are a number of nutrients the crop requires over and above nitrogen, phosphate, potassium and sulphur.

Boron (and Calcium) plays a key role in cell wall biosynthesis, carbohydrate metabolism, cell division and cell elongation. This ensures the crop has a good plant structure. It is therefore critical during periods of rapid growth -  particularly important as the crop enters stem extension. Boron also has a role in pollen germination. Adequate boron levels ensure even flowering, which in turn can lead to higher seed set.

Magnesium is well known for its role in photosynthesis, being a central part of chlorophyll. However the majority of magnesium required by the oilseed rape plant is taken up in a short period just prior to flowering. An adequate supply during this time is therefore essential. Recent trials confirm this. Crops showing higher levels of magnesium concentration in the leaves have a tendency to produce the higher yields.

Manganese is also involved in photosynthesis during the growing season. Another important role is the function of carbohydrate metabolism and lipid synthesis. This has an effect on oil production. Crops deficient in manganese are likely to suffer from lower oil content and also lower seed yields.

Molybdenum deficiency in brassica crops is widely known as “whiptail”. It’s primary function in the plant is to improve nitrogen utilisation by metabolising nitrate. If deficiency occurs the leaves become pale and limp. This can reduce the leaf area available for intercepting sunlight. This can lead to reduced photosynthesis, resulting in a lower pod yield. Unlike the majority of other nutrients, molybdenum becomes more available at higher pH so deficiency is often restricted to acidic soils.

YaraVita Brassitrel Pro was developed specifically for the oilseed rape 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 3.0 lt/ha applied in the spring just prior stem extension, delivered an average yield increase of 0.27 t/ha, which correlates to a 6.0 % yield increase.

With some crops suffering the effects of Rape Winter Stem Weevil damage then a decision needs to be made. Crops where the main stem has been decimated are unlikely to recover, however others will need some TLC. In these situations is it vital to maintain the focus and marginal gains become very important. With forward OSR prices where they are, a yield increase of 30-40 kg/ha will cover the cost of the Brassitrel Pro application. A 2 t/ha crop with a 6.0 % yield increase means 120 kg extra yield, still an ROI of 3:1.

Yara Invests in R&D 

Yara is a knowledge-based company and this means that we are always investing back into research and development – this includes a number of field trials.

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.

Sulphur Response

Each year, Yara invests in trials looking at sulphur response, a very important nutrient that also increases uptake of nitrogen in to the crop. In the wheat trial, we had a yield response of 0.3t/ha from around 50kg SO₃ in the AN-based product comparison. If we use £250/t for feed wheat, 0.3t/ha response from sulphur gives you £75/ha. If we use our longer-term average for sulphur response in wheat of 0.85t/ha then it would be £212/ha.

For oilseed we ran a similar trial and got a 0.35t/ha response from 73kg, if we use £516/t for oilseed then this is £180/ha. Longer-term sulphur response data gives an average of 0.5t/ha response; which would be £258/ha.

Micronutrient Trials

Another area where Yara invests in R&D trials is micronutrients. If we look at a wheat trial first, we were comparing YaraVita MAGPHOS K and CROP BOOST in combination with YaraVita GRAMITREL at T1, to see which is the best option at the T0 timing.

CROP BOOST, (containing P, K, Zn and Mg) when used in combination with GRAMITREL, at T1 gave the best increase with 0.6t/ha extra yield which, if we use £250/t feed wheat pricing, is £150/ha benefit - a great 4:1 return on investment!

We also had a trial on potatoes looking at micronutrients +/- biostimulants, here we were looking at MAGPHOS K +/- biostimulants and MANCOZIN alone. The addition of the biostimulant to MAGPHOS K increased the marketable yield by 4t/ha. The biostimulant on its own also had an impressive increase in yield compared to the control.

For more of Yara’s trial results from this season please visit Agronomy Advice

Digital Tools Help Maintain Yield Resilience

With crops, on the whole, looking good as we go towards the end of the year, using digital tools after winter can help keep the crop momentum going in 2023.

Once crops come out of the winter it can be difficult to know how much nitrogen (N) they have taken up, which means the first N application can be a bit of a guess. In order to increase efficiency it would be better to know the crop uptake before we decide on the N rate so that the crop isn’t over or under-fertilised. A quick and easy way to do this for cereals and oilseed is to use the photo analysis part of the Atfarm app.

It works by taking photos within the app of the crop which are then compared to several 100,000 images within our database. From this we can determine how much nitrogen has been taken up by the crop and translate that into a nitrogen recommendation. This then takes the guesswork out of that first application and could save you wasting fertiliser.

As well as monitoring biomass, as mentioned in previous columns, there is the variable rate nitrogen application maps (VRA) within Atfarm, as well as N-Tester functionality. In spring VRA (both N-Sensor and Atfarm) and N-Tester can be invaluable for increasing nitrogen use efficiency, productivity and potentially decreasing overall nitrogen use.

Using Atfarm to Monitor Crop Growth

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 mild sowing conditions many crops are looking well and enjoying the unusually warm soil temperatures for this time of year. 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 field of oilseed – does this mean that a bird scarer needs moving there? Or if an area within a field is showing slightly lower level of growth/colour difference, this could indicate a nutrient deficiency that needs addressing before if begins to affect yield.

Foliar P on Cereals Averages 1t/ha Yield

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

In particular, later drilled crops don’t have as long to establish much biomass i.e. decent root systems, 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 uptake is much more efficient 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 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 nearly 1t/ha, making it well worth the investment.

Digital Tools Help Maintain Yield Resilience

With crops, on the whole, looking good as we go towards the end of the year, using digital tools after winter can help keep the crop momentum going in 2023.

Once crops come out of the winter it can be difficult to know how much nitrogen (N) they have taken up, which means the first N application can be a bit of a guess. In order to increase efficiency it would be better to know the crop uptake before we decide on the N rate so that the crop isn’t over or under-fertilised. A quick and easy way to do this for cereals and oilseed is to use the photo analysis part of the Atfarm app.

It works by taking photos within the app of the crop which are then compared to several 100,000 images within our database. From this we can determine how much nitrogen has been taken up by the crop and translate that into a nitrogen recommendation. This then takes the guesswork out of that first application and could save you wasting fertiliser.

As well as monitoring biomass, as mentioned in previous columns, there is the variable rate nitrogen application maps (VRA) within Atfarm, as well as N-Tester functionality. In spring VRA (both N-Sensor and Atfarm) and N-Tester can be invaluable for increasing nitrogen use efficiency, productivity and potentially decreasing overall nitrogen use.

Managing Risk When Costs Are High

When a lot of aspects of farming are out of our control, we need to focus on what we can manage by minimising any risks coming on to farm.

Certain management decisions bring in yield resilience rather than fragility and this can include a number of things. For example, we need to minimise nutrient loss and application costs whilst maximising application accuracy, all whilst having environmental costs in mind too. Having good quality inputs can address some of the risks so that we are managing risk out and not in.

Dry weather in spring means that crops need to be even more resilient to cope with the lack of moisture and have a root system that is large and deep enough to access water further down the soil profile. We need to maintain growth momentum once crops start growing again in the spring, which can be at quite low temperatures, 5°C for cereals and oilseed. Our first fertiliser application is vital as it gives the crop the best chance of accessing the nutrients applied as they are will have started growing before you’ve been able to get onto the land.

This can affect the fertiliser choice because not all nitrogen-containing fertilisers are plant-available straight away. Nitrates are the most available form for plants to take up immediately, without any conversions needing to occur, therefore ammonium nitrate (AN) products provide immediately available nitrogen to the crop. If we look at urea-based fertilisers they have to undergo a conversion in the soil before they become plant-available and therefore the crop has delayed access to the nitrogen.

Depending on soil conditions this can take 6-8 weeks and therefore we could really be slowing down the crop momentum; which we don’t want to do at that key timing in the spring. So, if you are concerned about this delay stopping crop momentum, apply a nitrate based fertiliser, such as YaraMila 52 S or ACTYVA S, as your first spring top dressing. Aim to apply the first 50-70 kg N/ha with either of these products that will also supply fresh, immediately available PK&S to these crops.

Straw and Grain Nutrient Removal

If you remove straw then you also remove the nutrients that are contained in it, which is fine of course but then 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 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 CROPBOOST, 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 yara.co.uk/agronomy-advice/

Simplicity – the Ultimate Sophistication?

When buying fertiliser for spring application, many people fall into the potential ‘trap’ of getting straight nitrogen without thinking about the knock-on effects of this. Whilst nitrogen (N) is the most important nutrient, without sulphur (S), phosphorus (P) and potassium (K) the crop won’t be able to grow effectively.

We know that levels of both N and S in the soil are limited, and therefore the deficit in requirement needs to come from manures or mineral fertilisers. With P and K, we rely on soil indices to tell us how much to apply, but even on index 2 and above, fresh applications give a better use efficiency due to availability in the soil at the time crops require the nutrients.

This leads on to a compound NPKS being a good option for cereals, not only for the first application in February, but all the way through for an easy approach to fertiliser. “Aren’t NPKS a lot more expensive?” I hear you ask. You might be surprised to find out that they are actually more cost effective than urea/straight AN products are, and here’s why.

If we look at straight N then we have to think of applying P, K and S separately into the programme, this means we have 3 extra passes and 6 in total. If we think of the price of fuel at the moment, then this soon adds up to a significant amount - approximately £15/ha each pass.

If we think of the NPKS compound fertiliser then the additional benefits are 0.3t/ha from the spring P&K, 0.77t/ha from applying sulphur little and often and the increased accuracy of spreading is another 0.3t/ha. So, overall the benefit from applying an NPKS compound over straights is approximately 1.37t/ha, which at ~£240/t equates to nearly £330/ha for wheat crops.

Therefore, for a simple and cost-effective approach to nutrition for 2023, then a product such as YaraMila EXTRAGRASS (27-5-5+ 6% SO₃) is a really good option.

Well-timed nitrogen to hit protein spec

If you are aiming for protein spec with your milling wheat this year, then the timing of nitrogen is the key. In order to hit the protein target that millers are looking for, then a separate application of nitrogen is required after the flag leaf final dressing.

The application needs to be separate in order to ensure the nitrogen goes towards building up the protein level within the developing grain. 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 40kgN/ha (e.g. 120kg/ha of YaraBela Extran) at growth stage 51 (which is the start of ear emergence) can increase grain protein levels by up to 1%. This is possible to achieve without then compromising the yield. Yara trials showed that the separate application later 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, then an application of foliar urea (such as Chafer Nufol 20) applied later, at the milky-ripe stage, is the ideal timing for the same 40kgN/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 straight YaraVita Zintrac 700 will prevent this.

Read more about analytical services

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 YaraVita Biotrac, a biostimulant product, increased the yield in maize when applied in combination with YaraVita Crop Boost, by up to 4.4t/ha.

Read more about maize foliar nutrition

Is sulphur your first thought for new season pricing?

The majority of Irish arable soils are deficient in sulphur which means that most will need to factor this into their fertiliser strategy. It is easy to end up buying straight nitrogen products when new season pricing comes out, but most of the time an NS product is the most efficient way of feeding the crop.

For plants to utilise nitrogen correctly, sufficient sulphur levels are required due to the close relationship between the two nutrients. When applying sulphur it should go on little and often, the same way you would apply your nitrogen, because it has the same leachability characteristics in the soil. The addition of sulphur applied in this way typically increases the yield by an average of 0.50t/ha for wheat and oilseed.

However, the source of sulphur applied also makes a big difference. Elemental sulphur has to undergo an oxidation process before it becomes plant-available, this is weather-dependent and could take up to 6 weeks in the spring. Sulphur in the sulphate form is plant available and therefore the crop can utilise it quickly and efficiently.

The quality of the product is also a key factor for buying decisions and whether it spreads the required distance to give a good, even pattern. Fertiliser is a big investment and therefore buying a product that has a good CV, hard granules/prills (no dust), uniform in size and shape (no segregation), all nutrients in one granule/prill (even nutrition in the field) and has low emissions means an overall reliable return on investment.

YaraBela Axan (27% N + 3.6% S) is a high-quality NS compound which delivers these attributes and more. It is ideal for a multitude of crops when applied throughout the growing season, reducing the requirement of straight nitrogen, for a more efficiently grown crop.

Read more about nitrogen and sulphur

Deciding on final nitrogen rates

When we were first looking at nitrogen applications, back in the winter, it was advisable to review the final N rate once we knew what crops and economics were looking like in the spring. Well, now it is that time!

With current fertiliser prices, the cost of applying nitrogen is still high, however wheat and oilseed prices are also high; which means the economic optimum has shifted back up to more normal levels. If we do the calculations then the economic optimum is now around 190-200kgN/ha, rather than the 160-180kgN/ha when crop prices were lower back at the start of the year.

This means that it is now worth pushing for yields and, on the whole, crops also look like they have good potential.  The final dressing rate will of course depend on what you have already applied and also the crop type. If you are growing milling wheat then you will need to have the additional 40kgN/ha for increasing protein levels.

This can be added to the final application however trial work carried out has shown that, when it is applied as a separate dressing at growth stage 51 for solid or milky ripe for liquid, it can increase the protein levels by up to 1%.

YaraBela CAN 27%N is a quality granular fertiliser that spreads to over 40m and is ideal for the final application where straight nitrogen is required.

Read  more about determining final N rate

What can biostimulants do?

There are many types of biostimulants on the market, each with different purposes. What Yara products focus on is enhancing tolerance to abiotic stresses (e.g. extreme temperatures, drought, pesticide stress). They contain bioactive components such as fucoidan, mannitol, vitamins, organic acids, amino acids and also some of the nutrients that are involved in various mechanisms of the plant.

Ascophyllum nodosum, which is one of the compounds within Yara products, can induce hormone-like activity, improving the plant's hormonal perception and enhancing its effect. The composition of the product can also have an effect on many plant processes that could subsequently result in improved plant growth and yield improvement (e.g. increased photosynthetic efficiency, improved nutrient uptake, mitigation of abiotic stress effects through the mechanisms mentioned above, etc).

YaraVita Biotrac is a complex formulation containing nutrients and bioactive components from Ascophyllum nodosum, organic acids and vitamins. Biotrac can trigger various metabolic processes within the plant due to its composition; which impacts activities such as regulation of water, stress tolerance, stomatal conductance and detoxification of oxygen free-radicals.

This in turn can lead to improvements in the efficiency of plant processes and therefore result in improved plant growth and yield. Work shows that increases in both nutrient use efficiency, uptake and photosynthetic efficiency can be observed.

UK trials data has shown that when in combination with YaraVita micronutrient products, there were increases in yields observed. As an example, in a trial looking at different products on maize, when YaraVita Biotrac was used in combination with Cropboost or Gramitrel, the yield was increased above those products applied alone - showing improvement in the crop’s efficiencies.

Read more about how biostimulants

Influencing barley grain size, weight and number

Micronutrients have a key role to play in the growth of all crops and have an impact upon crop efficiency and, ultimately, yield. Manganese, copper and zinc are important micronutrients for cereals and can increase the grain size and weight when in sufficient supply.

Of course, the main influencers on grain size are nitrogen and sulphur but, with potential reductions in these macronutrients due to the current situation, we must also focus on which micronutrients can help influence the grain. Don’t forget the number of grains - which we can influence with well-timed micronutrient applications.

Grain size in barley can be reduced by late nitrogen applications. Secondary tillers form ears with small grains, therefore affecting the overall quality of the harvest. Nitrogen applied early will ensure a canopy that is large, containing high levels of stem carbohydrate that is translocated to the developing grain during maturation. If we go back to micronutrients then both manganese and zinc have roles in nitrogen metabolism by the plant and therefore sufficient supply will improve grain weight.

Research has also demonstrated that manganese, copper and zinc have all increased the Thousand Grain Weight (TGW) in barley. When applying these nutrients at the T1 fungicide timing, we see increases in the thousand-grain weight and the number of grains per ear can be positively influenced with copper and zinc in particular. These three micronutrients have also been shown in the literature to improve disease resistance in crops, a healthier plant has improved defence mechanisms against fungal infection and therefore is better able to deal with them.

YaraVita Mancozin contains all three key nutrients and is therefore an ideal product to apply with the T1 fungicide timing on barley

Read more about how crop nutrition affects barley

Cereal spring nutrition is more than just NPKS

Of course the first applications of nitrogen (and sulphur) are a high priority on farm, however, have you thought about micronutrient applications too?

Once crops begin the stem extension phase of growth they require a lot of nutrients to keep up with their rapid rate of development. This means the requirement for major nutrients increases but also the need for micronutrients increases as well. Don’t be fooled by terminology.  ‘Micro’ doesn’t mean that these nutrients are less important but that the plant requires them in smaller quantities. A deficiency of any nutrient can cause major problems within the plant. Think of the Law of the Minimum, where any limiting factor will affect the overall yield of the crop – micronutrients can be those limiting factors.

Of particular importance is magnesium. Part of chlorophyll it is therefore vital to efficient photosynthesis and is required by the T1 timing to ensure there is sufficient supply. Think of all the chlorophyll production during the rapid phase of growth once the crops take off – not having enough Mg will mean less light is captured, therefore affecting crop development and eventually yield.

Tissue testing is the only way to see what is in the plant at that moment in time and therefore which micronutrients you will need to apply to keep the crop at optimal levels. However, if tissue analysis isn’t for you then an easy and effective alternative for cereals is to apply a multi-nutrient product such as YaraVita Gramitrel . This foliar product contains all the nutrients required by cereal crops in one can, and can be used to ‘cover all bases’. Long-term independent trial data shows that, on average, there is about a 0.5t/ha yield increase from YaraVita Gramitrel applied in the spring.

Read more about cereal micronutrients

Kickstart oilseed growth this spring

Oilseed had favourable establishment conditions and on the whole fields were looking good going into the winter period. Now that regrowth is starting we need to keep that momentum going with spring starter fertiliser and key micronutrient applications.

One thing that could slow that momentum is the availability of phosphate (P) from the soil. When soils are below 8C phosphate availability is less than 10%, this means that when the crop starts to regrow it can’t access the soil-P straight away. P is important for shoot growth and root growth, which can also be compromised after winter if the roots have sat in waterlogged, anaerobic conditions. These factors can slow the development of the crop early-on, until soil temperatures increase.

An application of a compound fertiliser, containing N, P, K and S supplies that fresh P for the crop to take up immediately, whilst soil-P is unavailable. Potash (K) is also key for root systems, particularly those smaller secondary roots, increasing their number and density. Therefore a product such as YaraMila Actyva S (16-15-15 + 6.5% SO¬3) supplies fresh P and K, along with the nitrogen and sulphur, all of which are critical to early regrowth in the spring.

Other key nutrients for oilseed rape in the spring are magnesium, calcium, boron, manganese and molybdenum. All of these are in the crop-specific, foliar micronutrient product YaraVita Brassitrel Pro. Long-term independent trial data shows that an application of 3.0L/ha of YaraVita Brassitrel Pro at the onset of stem extension gives a 0.29t/ha yield increase to oilseed rape, which currently gives a return on investment of more than 8:1. Having all the key micronutrients in one product also makes the application simple and efficient.

These two products cover all the nutrients required to kickstart the growth of oilseed this spring and set the crop up for building yield.

Read more about oilseed nutrition

Planning first nitrogen applications

As crops got off to a good start in autumn, with favourable establishment conditions, many were quite advanced heading into winter. But after winter there is a risk that crop root systems have taken a knock by sitting in potentially cold, wet soils towards the end of last year. The last thing we want is to have good above-ground growth without the same below-ground to sustain it, therefore we need to keep the pre-winter momentum going once crops start to actively grow again.

In order to regrow that root system, fresh phosphate (P) and potassium (K) are vital nutrients to go with nitrogen (N) and sulphur (S) at the first nitrogen application timing. Soil-P, in particular, doesn’t become available until soil temperatures are 8^oC and above, whereas the crop starts growing at 4-5^oC. This means there could be a shortfall in available P. Along with a poor root system, this would be another reason growth could be stalled.

Applying an NPKS product, such as YaraMila Actyva S, at the first nitrogen timing will give the crop the vital nutrients it requires by a) providing immediately available nutrients so that the crop can take them up quickly and efficiently and b) replenish that root system to sustain the top-growth.

The second and/or third dressing(s) should then be an NS product such as YaraBela Axan, as we know that sulphur should be included with nitrogen applications. Split the sulphur into more than one application to get maximum nitrogen uptake and utilisation from sulphur sufficiency.

Read more about spring arable nutrition

Knowing your soils for more sustainable farming

January is almost over already and spring is fast approaching; now is a good time to look at your soil results to help plan.

UK soils have changed a lot in the last few decades; whether it’s the 97% sulphur deficiency found in soils sampled or low average organic matter levels across arable land. The importance of taking a soil sample is well-documented, but should you be investing in more than just basic soil analysis?
Identifying Limiting Factors

The basic analysis will give you P, K, Mg and pH; which is a good start but what about micronutrients, organic matter and soil microbial activity? All are important to plant nutrition and you may be unaware that your soils are low in one or more of these elements, a broad spectrum analysis + soil health will give you this information to enable you to manage them.

With more and more emphasis on sustainability, we should start with a farmer’s number 1 asset – soil! In order to be able to monitor your soil and pick up on factors indicative of its health, you have to monitor it in the first place. Organic matter (OM) is a key indicator of soil fertility through the retention of nutrients and the ability to feed beneficial microorganisms in the soil. OM can take a while to build but you need to know your starting point so that you can monitor your progress in building the levels within your soils.

Another important aspect of soil health is the microorganisms within that are key to having a fertile, productive asset to work with. By carrying out a Solvita test you can monitor the level of respiration within the soil; which is an indicator of the amount of microorganisms present.

Once you have baseline levels for OM and microorganisms then you can try different practices to see how they can help increase the levels of each and work towards a more sustainable soil. This will mean better nutrient use efficiency, as well as other key benefits to your crop’s productivity.

Read more about soil analysis

Foliar phosphate to kick-start growth

The early spring growth period in cereal crops is an essential phase during which the foundation for high biomass is established. Biomass is a fundamental prerequisite to achieving high grain yields, this biomass is the result of achieving a good population of main shoots and tillers.

The tillering phase commences after leaf 3 is fully expanded and generally finishes when the ‘double-ridge’ stage of development is reached (i.e. just before GS 30.) This growth stage is typically reached by mid-March. The final number of tillers can therefore be manipulated through the appropriate use of inputs. One such input is crop nutrition. Nutrient deficiencies, especially nitrogen and phosphate, will limit early spring growth and development, thus reducing the number of tillers produced – this is then exacerbated even more in waterlogged conditions, such as we have experienced this winter.

The root structure of waterlogged crops will be poor - small and potentially damaged roots means a lower ability to scavenge the limited nutrients from the soil. Phosphate in particular, which is unavailable at low soil temperatures (below 8°C), is important for root growth. With the soils having little to no available P in early spring, fresh applications become even more important. Solid P applications are somewhat inefficient therefore foliar P should be considered as an early option.

A foliar application of phosphate gives an ‘energy boost’ to the crop, stimulating the growth of roots and consequently shoots. Not only does this give an immediate benefit by way of recovery and repair, it builds resilience, enabling the crop to overcome further potential stress points. YaraVita Magphos K is an ideal foliar product for this timing, kick-starting the cereal growth at this early phase.

If you do choose to apply foliar P then do so as soon as you can travel but ensure that you are ready to come back quickly with an application of, ideally, NPKS to ensure the crop doesn’t lose momentum as we don’t want to spark growth off only to let the crop run out of steam once it gets going.

Read more about foliar phosphate

Use Yara’s Atfarm and increase your nutrient use efficiency

With potentially reduced nitrogen rates this season, what else can you do to increase the nutrient use efficiency of a) the nitrogen you can apply and b) all the other nutrients that a crop requires?

The use of a nutrient management plan (NMP) is not only a good way to calculate how much fertiliser you need but also should be part of the overall farm strategy. Historically NMPs have been quite simple, giving you an overall fertiliser rate for each field  - taking into account N, P and K.

As part of Yara’s Atfarm platform, we will soon be launching a more dynamic nutrient planning software package which will be much more helpful in planning your full crop nutrition programme (CNP).

After adding fields into Atfarm, it will give the user an option to create a nutrition plan (limited to cereals and oilseed currently but more crops coming soon!). By adding the usual parameters required for creating an NMP, such as soil type, rainfall area, yield, straw incorporated/removed, organic manures etc you will see the nutrition plan for your crop.

Where the Yara version of an NMP differs is the demand splitting of the nutrients. Rather than only giving you the total amount of N, P and K, Yara uses years of trials data and knowledge to split the nutrients out into the optimum timings, including all nutrients required for crop growth. Functionality also includes the ability to upload soil analysis results, which will then change your recommendation accordingly, making the interpretation and implementation of your lab results much easier.

These features make for a much more dynamic nutrition plan that will help improve nutrient use efficiency. Therefore, in a year where nitrogen is going to be one of the limiting factors of crop growth, the use of Atfarm can help improve overall nutrient efficiency and so increase the efficiency of the nitrogen that you are able to apply.

Read more about Atfarm

How fertiliser pricing affects economic optimum

Due to the European gas price moving from $6 to $42 (as I write this) we have seen the cost of production of fertiliser increase drastically due to natural gas being part of the manufacturing process – production costs have risen by €200/t this week alone!

Therefore the price you bought at will impact upon the economic optimum nitrogen (N) rate you should apply. If you bought earlier on in the year at €280 for example, your economic optimum wouldn’t have changed and you’ll be ok to stick with, say, 220kgN on winter wheat. However, if you have bought the majority of your nitrogen in the past few weeks (now above €500/t at the time of writing this) you may need to adjust your rate.

When looking at N dose trial data you see a response curve - as the rate of nitrogen increases, so does the yield – until you get to a certain point where the curve plateaus and then starts to decrease again at high rates of nitrogen. From this curve, you can see the biological optimum N rate. You can also calculate the economic optimum N rate; which takes into account the crop price as well as the fertiliser price.

From these trials we also know that the first 100kgN gives us the best response and therefore best return on investment (ROI) – no matter how much the fertiliser costs. The next 60kgN also gives us a good response and ROI. It is the next 50-60kgN/ha that relies on crop/fertiliser pricing, crop potential, weather etc to see if it is an economically viable application.

So what does all that mean?? If you had to buy at a high price you may need to reduce your fertiliser rate. Taking wheat as an example, we know that a lower rate of 160kgN/ha gives a good ROI, independent of fertiliser price. When we come to spring we can then re-evaluate whether the final 50-60kgN is required; based on crop pricing, potential, mineralisation and use of tools like the N-Tester to judge whether it is economically the right thing to do.

Read more about the economics of nitrogen fertiliser

Don't let your oilseed go hungry

Establishment is so important when growing oilseed, getting the crop up and away to combat pest pressure is the aim of the game.

At the time of writing there has not been any significant rain for weeks in some areas; which is a worry for newly emerging oilseed crops as moisture is key to getting good establishment. With rain on the forecast, hopefully, just in time, we should see a flush of growth from the nutrients released from soils. If fertiliser wasn’t applied at drilling you’ve got until the end of October to apply up to 30kgN/ha if you’re in an NVZ, to give the crop the best chance of establishing successfully.

Once oilseed has reached the 4 true leaf stage (GS14) it is safe to apply some of the key micronutrients to ensure growth isn’t hindered at all going into the winter. Oilseed can put a lot of biomass on over a short space of time if conditions are right, which means there is the potential for crops to deplete micronutrients levels in the soil.

A simple way to apply all of the key micronutrients required, in the autumn, on oilseed is to use a multi-nutrient, crop-specific product such as YaraVita Brassitrel Pro. This mix contains magnesium, manganese, calcium, boron and molybdenum – vital micronutrients for this crop, particularly if we want to aid establishment.

Yara conducts independent trials each year and over the past 6 years 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 applying as the return on investment is several times the cost of the product.

An added benefit from making sure the crop has all the nutrients it requires in the autumn is that a healthier plant is better able to cope with disease pressure and some of these nutrients have been shown to decrease the incidence of disease significantly. Think of it as a healthy animal not being as susceptible to illnesses as one that doesn’t have a sufficient nutritional diet, it is the same for plants.

Read more about micronutrients for oilseed rape

Micronutrients and plant health

Micronutrients are essential for growing a healthy, productive crop that is working efficiently throughout its lifecycle. There are different micronutrients that are key to each crop but on the whole, there are certain nutrients that are required at specific times to get the most out of your crops.

If we think about crop establishment, manganese and magnesium (which can also be thought of as a secondary nutrient) are the key micronutrients, on top of our major, or primary, nutrients nitrogen, phosphate and potassium. Magnesium is a key nutrient due to its central role as part of the chlorophyll molecule, without magnesium there wouldn’t be any chlorophyll and the plant wouldn’t be able to carry out photosynthesis.

Magnesium is also involved in enzymatic reactions in the plant, increasing their velocity as well as the formation of proteins and energy transfer. When a seed has germinated we want the growth to be unhindered and the plant’s processes to be working at full capacity to get the seedling growing away from pest damage for example. Magnesium has many roles within the plant and so having a deficiency during the early stages of growth will have a real impact on the overall capability of the crop establishing.

Whilst soils will have some level of magnesium present, it is often in an unavailable form to the plant and therefore deficiencies can easily occur, even during the early stages of growth. Mg deficiency symptoms are usually first seen in the older leaves with paler leaves initially and as it becomes more severe the leaves will have interveinal chlorosis (yellowing) and eventually the whole leaf will be yellow. This is due to magnesium being a central component of the chlorophyll; which gives plants their green colour.

Manganese is, again, important for enzymatic reactions in the plant, production of amino acids and chlorophyll as well as the metabolism of nitrogen. All of which are, of course, important for a newly-establishing plant. Symptoms of manganese deficiency are seen on the younger leaves as chlorotic spots and streaks which, over time, turn grey; with overall plant growth stunted. Deficiency is made worse by unconsolidated soils, which is why the areas around tramlines can appear darker green due to the more compacted soils.

You can see there are similarities between magnesium and manganese in which processes they are involved in, which is why these two nutrients are particularly important to plant growth, especially near the start of its life. If conditions are right, crops can put a lot of biomass on before winter and therefore autumn applications of magnesium and manganese can help ensure crop growth isn’t being held back at this critical phase.

Another reason to ensure the crop has good levels of micronutrients is the fact that a healthy crop is better able to defend itself against disease and pest pressure. Think of it as a healthy animal being less likely to succumb to disease than one that is lacking good nutrition from a balanced diet – it is the same for plants.
Work has been carried out to show how nutrients affect the incidence of disease in plants; large reductions in disease came from magnesium, manganese, copper, boron and zinc. These are the key nutrients to apply to autumn crops such as cereals and oilseed, the fact that applying them could also decrease the level of disease (and therefore fungicide spend) is an added bonus.

Lancrop laboratories see many routine tissue analysis results each year and if we look at the key nutrients for the 2021 season then there are still high numbers of deficiencies seen.

Deficiency levels from Yara Analytical Services data

To make life easier Yara has developed crop-specific products for cereals and oilseed in the form of YaraVita Gramitrel and YaraVita Brassitrel Pro which contain all the key micronutrients for the respective crops.

Gramitrel contains magnesium, manganese, copper and zinc, key for cereal crops, whereas Brassitrel Pro contains magnesium, manganese, calcium, Boron and molybdenum which, you’ve guessed it, are key for the oilseed crop. Having all the key nutrients in one can takes the hassle out of the autumn application and these products tank mix with most autumn pesticides too (you can check your mixture at tankmix.com). You can then follow them up with another application in the spring to catch the key growth timing or take a tissue test to go down the more precise route of applying straight micronutrients.

Whilst having a healthier plant might sound like a good thing can you equate this to yield increases? The answer to that is yes! Yara carries out trials on these products each year and there is a long-term average yield benefit over the past 6 years of 0.30t/ha from both cereal and oilseed crops. However each season is different – for example, this year’s trial gave a massive 1.0t/ha yield increase from 2 applications of Gramitrel (autumn and spring)! The return on investment (ROI) can be huge when you get these kinds of increases but there is also a good ROI on the long-term average of 0.3t/ha, making the applications worth it.
So, prevent your crops from lacking nutrition this autumn that will stop them from growing at their optimum and giving them the best chance of overwinter survival and, ultimately, yield next harvest.

Read more about YaraVita micronutrients

Why is fertiliser traceability important?

People like to know where the things they buy originate from, so being able to trace products from production to end-use is becoming more and more of a requirement. Do you feel the same way about your fertiliser?

Being able to trace each product back to where it was produced is vital for a number of reasons. For one, if there happens to be an issue with a particular product then it is easy to trace it back through its journey to find out where the problem occurred. Having the ability to track a product in this manner gives you the reassurance that you can trust the product. A further reason for the increasing importance of traceability is the ability to calculate the carbon footprint of your crop, a topic companies and consumers alike, are becoming more interested in.

Each product from Yara has a label that contains information unique to that product. On a 600kg bag of YaraBela Axan, for example, can see from the front of the bag, at the bottom right, which factory the particular product has come from; which for example could read Sluiskil – our factory in the Netherlands. The back of the bag has lots of information about the product including the product grade code and, again, the factory where it was produced. This information is particularly useful when it comes to spreader settings as there will be particular settings for YaraBela Axan from Sluiskil (also can be abbreviated as SLU). Using the product code and the factory of origin you can look up, on your spreader manufacture’s website, which spreader settings are required for that particular product.

Another useful label is in the inner liner – this will tell you which bagging facility the product came from – i.e. AVO would mean the Avonmouth facility, along with a unique bag number.

You can rest assured that any products you buy from Yara can be traced back to where they were bagged or filled, to the factory they were produced at, and also the batch to which they belong.

Read more about fertiliser traceability

Don't gamble with P and K in the autumn

Depending on pricing, it may be tempting to take a PK holiday when planning the coming season’s nutrient strategy.

When prices are higher then it probably isn’t the year to try and build indices as, economically, it might not be viable, but we still need to think about crop offtakes and a maintenance application for P&K. If we are only applying a minimum dressing to cereals this season then the most important detail is to make sure it is applied as a spring application. 

Soil temperatures in the autumn soon start to drop, especially if you’re delaying drilling due to grass weed control. Phosphate availability and crop uptake are greatly reduced in cold, wet soils therefore if you’re applying it in October/November it is unlikely to be taken up by the plant (and won’t become available in early spring).

So if we, again, think about the economics of this spring application surely it is better to apply 0-24-24 or straights because they are the cheaper option? Actually, these two options are one of the more expensive ways to apply P, K  and S due to the additional cost of the extra passes (labour, fuel etc), therefore you lose the saving you made on the product through these overheads.

Applying a compound NPKS, such as YaraMila 52S, at that first nitrogen timing gives you a spring PK yield benefit (on average 0.31t/ha), a sulphur yield benefit (on average 0.9t/ha when followed up with NS product) as well as enabling you to have a minimal number of passes. Whilst the amount of P&K might be lower, you should still be applying enough to cover the crop offtake and therefore aren’t depleting soil reserves. Another approach is YaraMila Extragrass applied all the way through the season – both of these options give you well over £100 margin over applying straight nitrogen or P&K in the autumn/as separate applications.

Read more about phosphate and potassium

Grain analysis - How can hindsight help?

With harvest well underway everyone is busy, but spending a bit of time taking a grain sample for analysis could pay off for next season.

Grain analysis has been available in the UK for a long time, however, it is not often carried out on-farm as a routine like soil or tissue analysis. Results from analysis show nutrient levels in the grain and therefore can identify whether sufficient levels of each nutrient were present for the crop in that growing season.

Having this data can then show you whether your crop nutrition strategy worked; did the crop have everything it needed to grow to its optimum? This ‘look back’ at the season then allows you to change your fertiliser strategy for the next season i.e. if the grain results are coming back as low in manganese then you need to review the amount or timing of application next season.
Sulphur is a good example of how to utilise the results you get from the analysis of the grain. An N:S ratio of below 17:1 is the target for wheat; if the ratio exceeds this it is an indication that there wasn’t enough sulphur available to the crop when it required it.

It’s not just the major nutrients that are useful, micronutrients are also measured in grain analysis and are, again, a good way to see whether they were at sufficient levels throughout the season. Don’t forget Liebig’s law of the minimum in which any limiting factor has the potential to stifle optimum yield, this of course includes micronutrients.

Therefore, grain analysis is another way in which to fine-tune nutrition to ensure that the crop is getting what it needs when it needs it – ultimately getting towards that optimum yield.

Read more about grain analysis

Establishing oilseed successfully with starter fertiliser

The idea of a starter fertiliser for oilseed is to improve establishment and get the crop up and away as quickly as possible. It could be tempting to wait until the crop is up and established before applying fertiliser but this could lead to a self-fulfilling prophecy - if you haven’t set the crop up with the best chance from the off, you can’t expect it to establish well. So for application timing, fertiliser should be placed if possible or applied soon after drilling to give the crop the best chance to establish. Trials have shown that placing fertiliser can increase yields by around 0.2t/ha; which is significant with recent pricing for oilseed.

An NPK product is ideal as a starter fertiliser. We need phosphorus (P) for root and shoot development and potassium (K) also helps with root growth and water regulation; which could be very helpful if we hit a dry spell after drilling. By ensuring there is enough K for optimal stomatal opening and closing, the plant will be better placed to cope with drier conditions.

The rate of nitrogen applied can differ depending on whether you plan on placing or broadcasting the fertiliser, but you’re looking at 25-30kgN/ha at this timing. Any fertiliser should be applied before the 15th of September, to comply with nitrates regulations.
Trials work has also shown that using an NPKS in the autumn can help with overwinter survival rates too with 90-100% survival when compared to an NS grade at around 38% survival. Work has shown that potassium acts like an “anti-freeze” in the winter too by lowering the cell’s sap freezing point and preventing frost damage.

Therefore when thinking of all those points a perfect grade is YaraMila New 18's + S (18-6-11 + 2.5% S) to give your oilseed crop the best chance this autumn.

Read more about improving oilseed rape establishment

Rapid maize growth requires roots and energy!

A crop of maize can produce up to 50 t/ha of fresh weight in just 4 months! For this amount of growth to happen, over such a short timeframe, there needs to be a healthy, extensive root system for nutrient uptake right 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, this is why placing some at drilling helps by providing it in immediately available forms. However cold conditions at drilling aren’t the only weather-related issue for maize. In dry soils, as we’ve had recently, nutrient availability in general decreases. 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.

Later on in the season, once the crop has reached 1-1.2m high, maize can be given a further boost by applying YaraVita Safe-N 300. This helps maximise efficient leaf canopy development.

In recent trials, the application of YaraVita Crop Boost followed by YaraVita Safe-N 300 gave an extra 10% in dry matter yield.

Read more about maize foliar nutrition

Hit protein spec with well-timed nitrogen

If you are aiming for protein spec with your milling wheat then the timing of nitrogen is the key. Reaching the protein target that millers are looking for requires a separate application of nitrogen after the flag leaf final-dressing.

The application needs to be separate in order to ensure the nitrogen goes towards building up the protein level within the developing grain. 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 40kgN/ha (e.g. 120kg/ha of YaraBela Extran) at growth stage 51 (which is the start of ear emergence) can increase grain protein levels by up to 1%. This is possible to achieve without then compromising the yield. Yara trials showed that the separate application later 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 then an application of foliar urea (such as Chafer Nufol 20) applied later, at the milky-ripe stage, is the ideal timing for the same 40kgN/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 straight YaraVita Zintrac will prevent this.

Read more about increasing grain protein content

Don't make hasty fertiliser purchases

When fertiliser applications are still going on you’re probably not thinking about next season’s requirements, however, don’t get caught out by the fertiliser industry pushing you to order quickly, without planning, once the new season pricing comes out.

We know that the majority of UK arable soils are deficient in sulphur so it is likely you will require a product containing sulphate, an immediately available form of sulphur for plants. Trial work has shown that sulphur should be applied little and often with nitrogen to get a yield increase of more than 0.5t/ha, therefore decreasing the amount of straight nitrogen required.

P and K requirements also need to be planned, the timing for P and K is crucial to meet the nutrient demand. Irrespective of your indices, 35kg/ha of fresh P and K should be applied in spring, just before the crop demand is at its highest; which is March to May. We know that 70% of P is taken up in this 6-8 week period, therefore it makes sense to apply it when it requires it, in a plant-available form. There is also a yield benefit to this fresh, spring-applied approach of 0.30t/ha on average.

Another consideration should be ammonia emissions. During dry conditions, there is a greater risk of volatilisation, and therefore ammonia is released into the atmosphere. The source of nitrogen you choose can make a big impact on the level of these emissions. For example, the emission factor for urea is 13.8% whereas ammonium nitrate (AN) has one of the lowest ammonia emissions at 2.7%. So, by using AN rather than urea you are reducing ammonia emissions by 5 times. If you are thinking of reducing emissions by using urea + inhibitor in the future, emissions from this combination are still 2.5 times greater than AN – making it the best option for cleaner air.

So with all those things taken into account a good fit for that first spring timing on most crops is YaraMila Actyva S (16-15-15 + 6.5% SO₃) with subsequent applications an NS compound such as YaraBela Axan (27%N and 9%SO₃).

Try our fertiliser selector tool

Keep your wheat greener for more yield potential

When it comes to the T2 flag leaf application there are a few points that we need to consider to ensure the crop is well equipped for the next stages of development.

The best way to know what micronutrients are in the crop is to carry out tissue analysis. This will give you an idea of what could be edging towards deficiency and therefore gives you time to order the right micronutrients to go into the T2 spray. What we don’t want to do is only use tissue testing when we see a deficiency symptom, as this means that potential yield is already being affected.

Luckily there is some rain in the forecast which means crops will finally be able to access the nutrients in the soil therefore make sure you allow 3-5 days or so after the first rains to enable this to happen, otherwise you might get skewed results.

A key micronutrient at this timing is magnesium (Mg). We want to keep the canopy green so that it can intercept light and eventually turn this into yield, magnesium can help with this. Mg is the central component of the chlorophyll, the more chlorophyll the more light interception. If there is a shortage of Mg then this process won’t be working at full efficiency and therefore yield won’t reach its full potential. We want to remove any limiting factors to the crop therefore ensuring it has the full ability to capture the light is critical.

Foliar phosphate and potassium can also help at the T2 timing. Phosphate is a key part of energy transfer within the plant and therefore is important for the process of redistributing stem carbohydrate as the crop moves towards grain production. Potassium also has a key role in this process therefore a useful foliar product at this timing is YaraVita Magphos K. This product, as the name suggests, contains all three of the nutrients mentioned and is a great fit for the requirements of the crop at this crucial timing, applied at 5 litres/ha.

Read more about maintaining wheat green leaf area

Reach that maize yield potential with foliar nutrition

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 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.

Maintaining green area duration in oilseed rape

As oilseed crops are now flowering we need to think about maintaining the green area duration (GAD) to ensure we can get the best yields. Keeping the crop greener for longer means that it is able to intercept more light (energy) which, via photosynthesis, it can use to ‘fuel’ pod fill and therefore create yield. Light is intercepted by the green parts of plants, this includes the green pods too once flowering has finished. So by maintaining the green parts of the plant you are effectively extending the period where the crop can turn energy into yield. 

Foliar nitrogen is an effective method of maintaining the GAD and there are a few options to choose from to suit each grower’s individual needs. Foliar urea is a popular option that typically gives an extra 0.25t/ha yield (worth over €97/ha) from 200l/ha application at the end of flowering.

Some other options for foliar nitrogen are YaraVita Safe-N 300 which, again, is applied at the end of flowering or YaraVita CropLift Pro (applied at the same timing). YaraVita CropLift Pro also contains a vast range of other nutrients, both macro and micro, to give the crop a boost. This could be particularly beneficial this season due to abiotic stresses on the crop such as low levels of rainfall.

Trials conducted in 2020 showed average yield increases of 0.35t/ha from an application Safe-N and 0.33t/ha from the application of CropLift Pro, both at the end of flowering.

Read more about oilseed rape nutrition

Crop economics vs nitrogen management

The amount of nitrogen we apply to a crop is influenced by a number of factors, but two particular principles are the main focus.

Firstly is the biological requirement - the amount required to satisfy the crop’s demand, after the soil supply has been factored in. This is where the use of analytical tools, whether destructive analysis via a laboratory or by data collection from crop sensors/images, comes into its own. The second is the economics at the time of application, which is a function of the crop and nitrogen fertiliser value.

If we consider the current economics, comparing present-day with 12 months ago, shows that whilst both grain and nitrogen fertiliser have increased, grain prices have risen by a higher percentage. We can use this information to calculate the ‘Breakeven Ratio’, i.e. how much grain is required to cover the nitrogen value. This calculation reveals that the grain:nitrogen ratio has moved down from 5:1 to 4:1 in the wheat crop. Using the well-established AHDB RB209 Guidelines, then this affects the optimum rate of nitrogen by adding an extra 10 kg N/ha into your planned recommendation.

Of course, the value of your nitrogen will have been affected by your purchasing policy. Those that purchased the bulk of their requirements early will actually be operating at an even lower breakeven ratio, i.e. 3:1. If you are in this position then you should be considering adding 20-30 kg N/ha onto your recommendation. This extra should be applied to your middle dressing where it will have the greatest impact on yield and profitability, then you should start to focus back on the biological aspects i.e. ensuring sufficiency of supply with the final application. This final application can be fine-tuned using Yara’s tools and services e.g. Atfarm and N-Sensor.

Read more about spring arable nutrition

Spring nutrition doesn't stop at NPK and S

The fertiliser spreaders have been busy applying macronutrients but have you thought about micronutrients at this time too?

Once crops start to extend they require a lot of nutrients to keep up with their rapid rate of growth. This means the requirement for major nutrients increases but also the micronutrients. The term ‘micro’ doesn’t mean that these are less important but means that the plant requires them in smaller quantities; a deficiency can still cause serious growth issues within the plant.

Magnesium, which is part of the chlorophyll and therefore vital to efficient photosynthesis, is required by both cereals and oilseed in the spring. Think of all the chlorophyll production during the rapid phase of growth once the crops take off – not having enough Mg will mean less light capture and therefore will affect crop development and, in turn, yield. As well as Mg, manganese, copper and zinc are key for cereal crops and manganese, calcium, boron and molybdenum are vital for oilseed.

Tissue testing is the only way to see what is in the plant at that moment in time and therefore will show you which micronutrients you need to apply to keep the crop at optimal levels. If you don’t want to carry out a tissue test then you could apply a multi-nutrient product such as YaraVita Gramitrel (Mg, Mn, Cu, Zn) on cereals and YaraVita Brassitrel Pro (Mg, Mn, Ca, B, Mo) on oilseed. These products have the specific, key nutrients required for those crops and can be used to ‘cover all bases’ if tissue analysis isn’t possible.

Trials carried out in 2020 by Yara showed that applying these micronutrient mixtures gave 0.78t/ha yield benefit in wheat from 2.0l/ha at T1, with the long term average giving 0.41t/ha (2016-2020). For oilseed at stem extension, we got a 0.59t/ha yield increase from 3.0l/ha with a long term average giving 0.30t/ha (2015-2020).

Read more about spring arable nutrition

Keeping momentum with foliar applications

I have spoken previously about keeping the crop momentum going and, along with your first nitrogen dressing, foliar applications of nutrients can also play a part in this.

YaraVita MagPhos K can be a useful tool at this early timing. As the name suggests it contains magnesium, phosphate and potassium and is a great way to keep the momentum going. Applied at the T0 timing, a week or so after you’ve applied your first fertiliser application, it will give the crop a boost between the nitrogen applications.

It does this by being taken up more efficiently through the leaf for effective utilisation, therefore enabling the crop to immediately access the Mg, P and K. Another benefit of this application is the effect on the roots, both P and K are key for building the root system. This is then beneficial for improving the uptake of the nutrients applied at the first nitrogen dressing as well as subsequent applications.

This two-pronged approach makes sure that the crop always has access to these key nutrients as it moves towards that rapid phase of growth and that its growth doesn’t stall in between nitrogen applications.

The next key timing for a foliar application would be with the T1 fungicide timing. To keep things simple you can use the crop-specific micronutrient mix for cereals, YaraVita Gramitrel, which contains Mg, Mn, Cu and Zn. This covers the key micronutrients for cereals and therefore is a useful tool if you don’t want to do tissue testing.

However, if you think that you’ll have particular deficiencies then it is a good idea to take some tissue tests a couple of weeks prior to your T1 application so that you can order the specific micronutrients.

Read more about spring arable nutrition

First nitrogen applications

As crops got off to a good start in autumn, with favourable establishment conditions, many were quite advanced heading into winter. However, with above-average rainfall levels in December and January, there is a risk that their root systems have taken a knock due to sitting in wet, anaerobic conditions. The last thing we want is to have good above-ground growth without the same below-ground to sustain it, therefore we need to keep the pre-winter momentum going once crops start to actively grow again in a few weeks’ time.
In order to regrow that root system fresh phosphate (P) and potassium (K) are vital nutrients to go with nitrogen (N) and sulphur (S) at the first nitrogen application timing. Soil-P, in particular, doesn’t become available until soil temperatures are 8^oC and above, whereas the crop starts growing at 4-5^oC – meaning there could be a shortfall in the available-P. This would be another reason growth could be stalled, along with the poor root system.
Applying an NPKS product, such as YaraMila ActyvaS, at the first nitrogen timing will give the crop the vital nutrients it requires by a) providing immediately available nutrients so that the crop can take them up quickly and efficiently and b) grow that root system back to sustain the top-growth.
The second and/or third dressing(s) can then be an NS product such as YaraBela Axan, as we know that sulphur should be included with nitrogen applications to split the sulphur into more than one application and also get maximum nitrogen uptake and utilisation from sulphur sufficiency.

Read more about spring arable nutrition

Soil sampling can help monitor sustainability

January is almost over already and spring is fast approaching; now is a good time to do some soil sampling if it wasn’t done in the autumn.

UK soils have changed a lot in the last few decades; whether it’s the 97% sulphur deficiency found in soils sampled or low organic matter levels across arable land. The importance of taking a soil sample is well-documented, but should you be investing in more than just basic soil analysis?

Identifying Limiting Factors.

The basic analysis will give you P, K, Mg and pH; which is a good start but what about micronutrients, organic matter and soil microbial activity? All are important to plant nutrition and you may be unaware that your soils are low in one or more of these elements, a broad spectrum analysis + soil health will give you this information to enable you to manage them.

With more and more emphasis on sustainability, we should start with a farmer’s number 1 asset – soil! In order to be able to monitor your soil and pick up on factors indicative of its health, you have to monitor it in the first place. Organic matter (OM) is a key indicator of soil fertility through the retention of nutrients and the ability to feed beneficial microorganisms in the soil. OM takes a long time to build but you need to know your starting point so that you can monitor your progress in building the levels within your soils.

Another aspect of soil health is the microorganisms within the soil that are key to having a fertile, productive asset to work with. By carrying out a Solvita test you can monitor the level of respiration within the soil; which is an indicator of the number of microorganisms present.
Once you have base-line levels for OM and microorganisms then you can try different practices to see how they can help increase the levels of each and work towards becoming a more sustainable soil. This will mean better nitrogen use efficiency as well as other key benefits to your crop’s productivity.

Read more about soil testing and analysis

Planning tillage nitrogen applications

In contrast to last season, there are many well-established crops out there that went into great conditions and put on good biomass going into the winter. On the whole, we have had a mild winter so far, if this continues through January and into February it could mean even more growth before the land is dry enough to spread fertiliser.

If your crops are forward this needs to be taken into consideration when planning your first nitrogen application, weather permitting, at the end of February. With a mild winter comes mineralisation, therefore nitrogen is available to the crop and many forward crops are showing how much nitrogen they have been able to take up so far by their amount of growth.

We want to keep the crop momentum going because we don’t want the crops to run out of steam before the period of rapid growth come March/April. However with forward crops then we don’t need to go on with as high a rate as we might with a late-drilled, backwards crop (up to 100kgN/ha). 60-70kgN/ha should be enough as a first dressing to maintain the momentum of a forwards crop, applied mid to end of February or as soon as possible after this is soils are still wet.

Ideally, an NPKS compound product, such as YaraMila New 18's + S should be applied as this gives the crop fresh phosphate when the soil-P might not be available yet, as well as sulphur to aid nitrogen uptake and utilisation. A second option is YaraMila Extragrass, another NPKS product, which can be used all the way through for cereals and oilseed for a straight forward macronutrient strategy.

Read more about YaraMila NPKS fertilisers