Keep up to date with all the latest arable agronomy advice with this advice column from Yara's chief arable agronomist Natalie Wood.
As we are into a New Year, a new subject! N,P,K,S and, more recently, Boron have been covered on a number of occasions - therefore let’s look to a lesser-discussed nutrient.
Molybdenum has been known to be an essential element in crop nutrition for many years. Its predominant role is in the conversion of the nitrate nitrogen that is in the leaf following uptake from the soil, into the nitrite that the plant requires for further dry matter production. The importance of it in this process is seen at its clearest in the legume crops e.g. peas and beans which can exhibit nitrogen deficiency symptoms as the fixation ability in the root nodules is severely compromised when deficient in molybdenum.
The plant can readily take up molybdenum via the roots, or directly through the leaf as it can translocate it throughout the plant. Deficiency symptoms would normally show in the oldest leaf, with these leaves being smaller than normal. Occasionally necrotic spotting can occur as the leaf nitrate levels rise to toxic concentrations.
Approximately 60% of the oilseed samples that came into the laboratories in 2019 showed deficient molybdenum levels. One explanation for this increase may well be associated with the agronomically correct decision to apply sulphur to this crop. As sulphur application rates increase, the more negative affect this has on molybdenum uptake. Some work published in 2006 reported statistically significant differences in molybdenum levels (i.e. deficiency) at the green bud and flowering growth stage in oilseeds following 100 kg SO3/ha applied as ammonium sulphate. Consider addressing this with applications of products such as YaraVita Brassitrel Pro or YaraVita Molytrac 250 during stem extension.
This autumn has been extremely challenging for some with the relentless rain we’ve had, those who have been able to drill will need to anticipate that soil nutrient levels are going to be low.
Due to such high levels of rainfall in the autumn there will have been a very high risk of nitrates and sulphates having leached from the soil. This means that there are lower levels of these key nutrients available for the growing crops and this needs to be taken into account when working out your nutrient management plan.
The levels of mineralisation will be very variable over winter depending on how much rainfall you’ve had as well as soil type and other local factors. This means that there is likely to be a low soil supply of nitrogen and sulphur in the spring therefore it is even more key to get your first nitrogen application on as early as possible.
If the weather permits then your first nitrogen application should be going on at mid-end of February, to give the crop the best chance of growing away as soon as possible in the spring. Therefore, building biomass that potentially hasn’t been possible over the winter through late-drilling.
Ideally the first application should be a nitrogen and sulphur containing product due to the close relationship between uptake of the two nutrients, especially at this early timing.
Nitrogen rates should be higher due to all the same reasons as above, for the first application you’d be looking at 70-100kgN/ha to ensure the crop has all it needs to build the biomass whilst it is able to and rapidly growing in early spring.
There is a lot of variation out there in terms of percentage of winter cereals drilled across the country, ranging from 0-100%. With crops going in to all types of soils, soil temperatures and conditions this autumn there is also a lot of variation across different fields.
This variation might not be visible at the moment due to the potential low biomass of the later-drilled crops, however variations in biomass may be evident when looking at satellite images. These can be accessed using the free web-based software AtFarm to monitor how the crops are growing throughout the season. AtFarm teams NDVI satellite images with the Yara N-Sensor algorithms to give a much more accurate colour-scale of variation thereby showing more variation than is possible using the limited NDVI images.
When we come into spring, due to the autumn weather, there is going to be a lot of differences across farms and fields in terms of leaching of nitrates and sulphates from the soil as well as ranges in the amount of nitrogen that has been mineralised over the winter period. All these aspects go towards creating variation in biomass. Using something like AtFarm to monitor the biomass enables you to see where the potential issues are in the field that might need further management as opposed to uniform fertiliser applications.
AtFarm also enables you to use the hybrid NDVI map to create a variable nitrogen application map with your chosen products that can then be exported to a variable rate spreader. This makes this free software a good introduction into working more precisely if you’ve not yet taken a first step into precision farming.
Historically, the interpretation of tissue testing analysis has been based on guidelines relating to early season crop growth stages and in many cases these guidelines have been established from potentially dated research sources.
Yara Analytical Services has gathered an unprecedented dataset of tissue analysis with millions of results built up over the years. This enables them to utilise this data to look at nutrient trends and benchmark nutrient levels against crop productivity. They were able to track how nutrient levels in various crops changed throughout the season and show, with confidence, evidence to change the current static guideline levels to growth stage specific guidelines for improved interpretation and in season crop nutrition decisions.
If we take nitrogen for example, the historical guideline is at 3%, whereas the samples in the dataset showed that the levels tracked 4% - which is in line with where growers would typically want N levels of a crop to be. Looking at phosphate then the guideline is 0.3% throughout the season, but we know the crop has a higher demand for phosphate in the spring and that demand reduces as the crop reaches maturity. The dataset of leaf analysis results reflected this change in demand, thereby giving cause to change to a dynamic guideline for leaf phosphorus that follows the same pattern throughout the crop cycle.
The project showed that all nutrients measured in a leaf tissue analysis follow their own pattern of rising, maintaining or declining tissue levels based on requirement at key crop growth stages. These patterns have been used to establish Yara’s new set of leaf tissue analysis guidelines. From 2020, we can look towards a dynamic guideline that changes as the crop grows, ensuring a more accurate representation of each nutrient within the crop at specific timings.
If you didn’t get around to soil sampling after harvest then now is a good time to think about ticking that job off the list before winter.
UK soils have changed a lot in the last few decades; whether it’s the 97% sulphur deficiency found in soils sampled or the low organic matters across arable land. Therefore everyone knows the importance of taking a soil sample; but should you be investing in more than just basic soil analysis?
The basic analysis will give you P, K, Mg and pH; which is a good start but what about other nutrients organic matter % (OM%) and microorganisms? All these aspects are important for healthy plant growth and efficient nutrient uptake; are you unaware that your soils are low in one or more of these elements?
Yara’s Analytical Services have processed over 20 million samples. This huge dataset has shown that after removing all the soils with limiting factors such as P < index 2, pH <6.5 and micronutrient deficiencies then there are a minority of soils that are sufficient in what a crop needs to grow to its full potential.
By using Broad Spectrum analysis you will get a detailed report of all nutrients, pH, CeC and OM%. These detailed reports can be used to compare practices across different fields or monitor improvements such as organic matter levels. Remember that when you go below 4% OM the nutrient availability of certain nutrients starts to decrease and this gets worse the lower the OM%. Building OM levels is a long-term process and should be thought of as part of a 10 year plan.
With a short dry spell there have been some able to drill recently, but reports are showing it’s only around a 1/3 of what would usually be in the ground by now.
When drilling cereals late there are a few things to remember in order to give the crop the best chance of establishing before heading into winter. Upping seed rates is essential as the plants won’t have chance to tiller before winter if the cold weather continues. There is increased pressure from slugs and also potential for seeds to rot with the levels of water around which, again, are reasons to increase rates. If worried about the crop being thick/too forward it is easier to manage a forward crop through use of PGRs than it would be to try and manage a backwards crop with little to no tillers in early spring.
Cold, wet soils mean that phosphate availability is low. Normally at Index 1 or above the soil would supply sufficient phosphate to get the plant through the establishment phase and up to spring, but if the soils are cold then it is just not available to the plant. Therefore, if there is a chance to travel once the crop is up then an application of foliar phosphate is essential. Foliar phosphate gets into the crop much more efficiently than solid phosphate does therefore an application of YaraVita MagPhosK will supply the crop with the majority of the rate applied.
This will give the crop the much-needed phosphate kick that is essential for both root and shoot development and so is key during the establishment phase.
Autumn is definitely here, with cold temperatures and a lot of rain in recent weeks. Making sure the oilseed crop gets off to a good start with nutrition means it’s better equipped going into winter.
Now is a good time to apply micronutrients to oilseed rape to cope with this period of rapid growth in the autumn. YaraVita Brassitrel Pro is a multi-nutrient mix with all the key nutrients for OSR and trials have shown an application in the autumn gives an average 0.3t/ha yield response over the past 4 years.
If you haven’t got any autumn nitrogen on oilseed rape then there’s still (limited) time left. Oilseed has a demand for nitrogen in the autumn due to how much biomass is generated before the winter dormancy period. 30kgN/ha should be sufficient for autumn growth and if you’re in an NVZ this is the nitrogen restriction on oilseed anyway.
If you’re thinking of broadcasting an NPK product then it might be better to save your money. Phosphate (P), as we know, is good for root development. However, phosphate is very immobile in the soil, only being able to travel 1mm. This means the majority of an application gets wasted due to its inefficiency.
Temperature of the soil also plays a bit part – cold, wet soils affect phosphate availability, making is less available to the plant.
Orthophosphate (which is the form most phosphate products are in) tends to become unavailable to the plant after a couple of weeks due to precipitating out with calcium or fixation to iron or aluminium ions within the soil. This means that the plant isn’t able to take it up anymore due to its change in chemical form.
Therefore, with all these factors, waiting until the spring to apply P (and K) is a better way to ensure that the P you apply gets into the crop at the right time when it requires it the most.
It is important to ensure wheat crops get off to a good start to give them the best chance to begin building biomass early on before they ‘shut down’ for the winter period. An earlier sown crop will have more leaves going into the spring; which equates to more roots and therefore it has more capacity for water and nutrient uptake when required in the spring.
With wheat crops being sown later in November and even December into colder soils they don’t have the time to increase their biomass much before they slow down their growth over winter. Therefore some extra help, in the form of micronutrients, for these later sown crops will help with nutrient uptake and growth pre-winter.
YaraVita Gramitrel contains a mixture of key micronutrients for cereals crops including Mn, Cu, Zn and Mg. It is a convenient way to get the nutrients that are particularly important for cereal growth into the crop at the key timings.
Manganese is key to establishment as it is necessary for photosynthesis and protein synthesis, aids meristem production and is an activator for many enzyme processes e.g. nitrate reductase.
Magnesium is a central part of the chlorophyll molecule of green plants, and as such, plays an important role in photosynthesis. It also plays an important role in the synthesis of proteins and in phosphate and nitrate metabolism so again is important at this early stage of growth.
Zinc also plays a role here as optimum zinc promotes auxin levels, aiding canopy development.
Recent Yara trials have shown that an application of YaraVita Gramitrel at 1-2L/ha in the autumn and again in the spring has given a 0.40t/ha yield benefit.
There’s plenty going on at harvest time to keep everyone busy but spending 10 minutes sending off a grain sample for analysis could save you money in the long run.
Grain analysis has been available in the Ireland and the UK for a long time, however it is not something that would be carried out on-farm as a routine like soil or tissue analysis would. Grain analysis shows what nutrients the grain contains and therefore whether the crop has had sufficient levels of each nutrient in the growing season.
By knowing the nutrient levels within the grain, you can see whether your crop nutrition strategy worked – did the crop have everything it needed to grow to its optimum? Having this information then allows you to change your fertiliser plans for the next season i.e. if the grain results are coming back as low in potash then this could mean you need to review the amount or timing of application next season.
A good example of how to utilise the result is looking at the sulphur level within the grain. You want an N:S ratio of below 17:1 in wheat – if the ratio exceeds this then it is an indication that there wasn’t enough sulphur available to the crop. We recommend that you apply 20kg S/ha for wheat and 30kg S/ha for oilseed, little and often, to ensure there is sufficient supply through the season.
Therefore, grain analysis is another tool in the toolbox to fine-tune nutrition to ensure that the crop is getting what it needs, when it needs it – ultimately helping towards that optimum yield.
With harvest in full swing it’s also time to think about soil sampling once crops have been taken off.
UK soils have changed a lot in the last few decades; whether it’s the 97% sulphur deficiency found in soils sampled or the low organic matters across arable land. Everyone knows the importance of taking a soil sample; but should you be investing in more than just basic soil analysis?
Basic analysis will give you P, K, Mg and pH; which is a good start, but what about other nutrients and microorganisms? All these aspects are important for healthy plant growth and efficient nutrient uptake; are you aware that your soils are low in one or more of these elements?
Yara Analytical Services have processed over 20 million samples since the early 1980s. This huge dataset has shown that after removing all the soils with limiting factors such as P < index 2, pH <6.5 and micronutrient deficiencies then there is only a minority of soils that are sufficient in what a crop needs to grow to its full potential.
By taking a broad spectrum soil sample you’ll know about these issues before it’s too late – when symptoms appear the yield is already taking a hit. Remember Leibig’s Law of the Minimum which states “A deficiency of any single nutrient is enough to limit yield”. With yields being pushed further, whilst costs savings are sought (such as P and K holidays) you could be limiting the effectiveness of any increased nitrogen applications.
Oilseed rape continues to be one of the only options for a break crop, despite the well-known problems trying to get it established. Drilling will start in August if weather conditions are favourable so now is the time to think about getting the crop off to the best possible start. Getting OSR established and away rapidly is the best way to try to counteract the various pests that are rife at that time of year.
NVZ rules allow up to 30kg/ha of nitrogen to be applied to the crop in the autumn however due to losses each year from cabbage stem flea beetle, pigeons or slugs, growers are reluctant to make that initial investment.
Phosphate is also very important for the crop at this crucial establishment phase. Phosphate is important for protein synthesis, root development and energy transfer within the plant. It has very poor soil mobility, moving less than
1mm, so placement at drilling makes it immediately accessible to the seed. As well as assisting tap root growth it also aids secondary root formation, assisting root structure development and water and nutrient uptake.
Potassium is also beneficial as sufficient levels help improve the crop’s tolerance to stress (as well as disease) meaning it would be better equipped to cope with colder temperatures heading into winter. An all-round healthy plant is better able to endure abiotic stresses therefore making sure all nutrients are sufficient in the autumn during active growth is vital.
With all of the above in mind I recommend a compound NPK fertiliser such as YaraMila ACTYVA S (16-6.6-12.4 + 2.6% S) as the easiest option for OSR this autumn. This will provide the crop with exactly what it needs to enable rapid establishment and growth into the winter.
There is increasing focus on industries today to reduce their environmental impact as much as possible. With more of a spot light being shone on agriculture for emissions and GHGs (Greenhouse gasses), the ability to calculate your carbon footprint as a farmer is increasingly relevant.
At Yara we developed catalyst technology which greatly (by up to 90%) reduces emissions of N2O (a GHG) from nitric acid production. Nitric acid is required in the process of manufacturing nitrate fertilisers. Greatly reducing the emissions from this process means that the carbon footprint of Yara’s nitrate containing fertiliser is also reduced by 40%.
However, once the fertiliser gets on to farm, it is up to the user ensure that the carbon footprint continues to reduce through best farming practice.
To get the most of the fertiliser at farm level you want to get the best Nitrogen Use Efficiency (NUE) from the fertiliser that you can. This comes from product selection, timing, rate, weather conditions, crop demand, soil properties, and more, to ensure that the fertiliser you are applying gets to the desired location and is taken up by the crop. By ensuring all these factors are taken into account then another 10-30% carbon savings can be made by minimising losses through leaching or volatilisation.
Therefore, by product selection and best practice growers can reduce their carbon footprint by half when using Yara’s nitrate fertilisers.
New season fertiliser prices always mean many orders will come in for straight nitrogen products – but is this the correct strategy?
With 97% of UK soils being sulphur deficient and spring P&K giving 0.25t/ha yield benefit this should influence your buying decisions, so that when it comes to next spring you’re not left wanting with a shed full of straight nitrogen!
For the crop to utilise nitrogen correctly sufficient sulphur is 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. 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 type of sulphur that is applied also makes a big difference. Elemental sulphur has to undergo an oxidation process before it becomes plant available which is weather-dependent and could take up to 6 weeks. Sulphur in the sulphate form is plant available and therefore the crop can utilise it quickly.
Applying fresh P & K with the first nitrogen timing means that the crop gets a fresh dose of plant-available nutrients when soil temperatures are perhaps not high enough for the crop to utilise what may already be in the soil. This also means that the phosphate and potash are there when the crop enters the phase of rapid growth and is at its highest demand for nutrients.
So before you make your orders in the coming weeks ask yourself “How much straight nitrogen do I actually need?”.
With a very dry start to this year, especially in February/March there was a fear that we would see another spring like last year with no rain coming until harvest time! This meant that a lot of growers put all their nitrogen on by T1.
This strategy is fine for trying to combat a dry season and I have written previous articles on that recently. However most of the UK has had a good dose of rain by now and this makes me question whether there will be enough nitrogen to get crops right through to harvest or whether a small application is required.
Using Yara’s N-Tester takes the guesswork out of this decision by telling you exactly how much nitrogen the crop still requires – let the crop tell you what it needs! This will be particularly useful this season with all different nitrogen regimes having gone on. The N-Tester works by measuring the level of chlorophyll in the plant which directly relates to the level of nitrogen in the plant. An algorithm then turns this into a nitrogen recommendation based on the variety. Remember that if you’re growing a milling wheat you will still need to apply an extra 40kgN/ha for protein, the N-Tester doesn’t account for this.
Being able to utilise tools like these helps ensure the correct amount of nitrogen is being used – you don’t want to a) waste money on excess nitrogen b) let excess nitrogen get into waterways etc. You will be able to make better use of nitrogen and therefore improve the overall nitrogen use efficiency of the crop which will become more and more important as legislation changes are made.
It is important to ensure that sugar beet receives balanced nutrition, this doesn’t mean only nitrogen, phosphate and potassium, but sodium, magnesium , boron and manganese too. All these nutrients are vital in producing a good root and sugar yield.
If these nutrients are in short supply, especially early-on, then plant establishment can be adversely affected. This reduces the crop’s potential for maximum root and sugar yield at an early stage and therefore is not working to its full potential throughout the growing season.
Statistics prove that the highest returns are always achieved when those key nutrients are kept at optimum levels within the plant. If leaf quality is not maintained through sufficient magnesium and manganese levels then reductions in both sugar yield and production are to be expected.
YaraVita Betatrel DF contains sodium, magnesium, manganese, boron, sulphur and a small amount of nitrogen, making it the ideal mixture of nutrients for sugar beet. Being a dry flowable YaraVita Betatrel combines the benefits of a suspension with the long-term storage characteristics of a dry product.
Against a background of great change, it is even more important to take control where we can to deliver impressive results, whatever the weather or the politics!
Maize is a fast growing crop, putting on up to 50t/ha of fresh weight over a 4 month period. Where there is rapid growth, such as this, the nutrient demand is high therefore ensuring sufficient supply of nutrients is key.
A 40t/ha crop will remove significant amounts of nitrogen, as well as P and K therefore it is important to ensure both organic and inorganic fertiliser applications are enough to satisfy this demand.
At this time of year nights can still be cold; this is hard for new maize plants to cope with due to their immature root systems. The roots aren’t able to scavenge for the required nutrients as efficiently, particularly important for phosphate which is immobile in the soil. Data from 2018 showed that 92% of maize tissue samples sent in were deficient in magnesium and 49% were deficient in zinc – these are two key nutrients required for a maize crop. YaraVita Maize Boost applied at the 4-6 leaf stage will supply fast-acting foliar phosphate with zinc, magnesium and potash for efficient uptake through the leaf.
Independent research has shown that P deficient maize plants growing in cold and/or acid soils utilise phosphate that is applied to the leaf much better than those plants already receiving adequate P from the soil. The rate of uptake by leaves of the deficient plants was twice that of the control plants which had the correct fertilizer applied, much more P was translocated from the leaf - particularly to the roots which maximises early root development.
During difficult years for growing maize, farmers estimated that YaraVita Maize Boost used proactively at the correct timing improved crop yield by over 20%. Farm trials conducted in a good maize growing year, raised starch analysis by an average of 20.10% following one spray at the 4 to 6 leaf stage. A further 19.50% was produced from a second spray at 8 leaves, again, proving the benefit of proactive applications.
Across the country oilseed rape has much variation in both growth stage and potential yield. This season has to be one of the most challenging that an OSR grower has had to deal with; from drought at establishment to the obvious flea beetle issues.
However it’s not all bad news out there with many OSR crops looking well and it’s these crops that we need to maintain in terms of green area duration (GAD) to ensure the best yield. Light is intercepted by green area within the plants, this includes the green pods too once flowering is finished. Maintaining the green area means maximum light interception which the plant converts to energy and therefore ‘fuels’ pod fill.
Foliar nitrogen is a good way of maintaining the GAD and there are a few options to choose from to suit each individual’s requirements. Foliar urea is a popular option which typically gives an extra 0.25t/ha yield (worth over £75/ha) from 200l/ha application at the end of flowering. If foliar urea is not for you then there is YaraVita Safe-N 300 (liquid) which, again, is applied at the end of flowering.
YaraVita CropLift Pro is another option for late foliar nitrogen on OSR. It 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.
At the time of writing this soils are currently very dry with no significant rainfall in the long-term forecast. So what does this mean in terms of nutrition?
f you haven’t already applied your second dressing on feed wheat then it might be necessary to apply the balance of your nitrogen due to current conditions. At least then it will be in the soil when the small amount of rain that is forecast arrives. If we have a very warm, dry year like last year crops are going to struggle therefore giving them sufficient nutrition early on will help towards their ability to scavenge whatever water is available at depth (wheat roots grow to depths of more than 2m).
It is important to keep the crop momentum going through this stressful period. If dry conditions continue as the weeks go by, then foliar nutrition, such as potassium, can help. Potassium is important for water use efficiency (WUE) and has been shown to increase WUE even on a crop that’s being irrigated. Potassium is part of the opening/closing mechanism of the stomata therefore if there is a deficiency the stomata don’t work as effectively. This could mean that more transpiration happens than is necessary, due to the stomata not closing properly, which in dry conditions would be very detrimental.
In addition ensuring that all micronutrients are sufficient gives the crop the best chance to overcome these kind of abiotic stresses. As mentioned in previous articles, limiting factors that you can take control of are key to crop momentum, especially in difficult years.
Most winter cereal crops are looking well now with cool, bright conditions which are great for growth at this time of year. Protecting those newly developing leaves at T1 is vital to ensure maximum light interception over the next few weeks.
There is a lot of talk about crop momentum at the moment; this also links to Liebig’s Law of the Minimum – ensuring there are no limiting factors in order to get the most out of the crop. There are many elements that could be a limiting factor – some of which we can’t do anything about such as light, temperature and the amount of rainfall.
However there are many factors that you can influence. Making sure you take control of them is key to getting the best of out what you have. For example, there are key micronutrients that cereals require at different times of the growing season – making sure these are all in sufficient supply means you’re giving the crop what it needs when it needs it, and helping to keep that momentum going.
How do you know which micronutrients to choose? The most accurate way is to take a tissue test and send it to a lab to be analysed – this will tell you what’s in the crop and therefore what it needs to make sure micronutrients aren’t limiting factors.
If you want to cover most key micronutrients required for wheat or barley, go with an application of YaraVita Gramitrel at the T1 timing. This can always be backed up by straight micronutrients if anything is still a little low when you come to T2.
Now crops are entering the rapid period of spring growth tissue testing is the ideal way to see what the crop might be lacking this spring.
There are different stages of deficiency within a crop; the obvious one is where there are visible symptoms present which enables you to determine which nutrient is lacking. However there is a ‘hidden hunger’ stage which comes before this. As the description suggests, this is where the crop isn’t displaying any visible deficiency symptoms, but the yield is starting to be affected due to the actions of that nutrient not working at 100% efficiency.
This is ideally where you want to catch the deficiency before it transitions into the visible symptoms – once these have appeared then the effect on the yield is greatly increased. The only way to catch this ‘hidden hunger’ stage is to send a tissue sample off to a laboratory. This then gives you time to get the results back and order any micronutrients that might be in insufficient supply to apply before you start to see those symptoms and potentially lose yield.
If you get the results back with multiple nutrients in the intermediate deficiency stage then it might be a better option to use a multi-nutrient product such as YaraVita Gramitrel (wheat) or YaraVita Brassitrel Pro (oilseed).
If you are showing as particularly deficient in certain nutrients then straight products such as YaraVita Mantrac, Magflo 300, Zintrac etc might be more beneficial.
The key is to do something when you get your results back – too many times I have heard that people have gone to the trouble/expense of taking a tissue test but then not following up on the results by applying anything. If you are striving for a high yield then these small gains all add up to create that yield, so make the most of the tools you have available.
The potato crop requires potassium in large quantities, 50% more, in fact, than nitrogen. A 38.5t/ha crop can remove more than 120kg/ha of nitrogen whereas it can remove over 200kg/ha of potassium. Both of these macronutrients are important throughout vegetative growth, tuber formation and bulking.
Nitrogen is important for leaf and tuber growth and is recycled from lead to the tuber during bulking, the same can be said for potassium. When thinking of potassium then as you can see from the removal values that it is key for high yields and maintaining tuber integrity.
Phosphate is also required in relatively large quantities during early growth due to its importance in root and shoot development and tuber set but also later on in the season for bulking.
Calcium is a crucial nutrient as it plays a role in important quality parameters. Potatoes need calcium to strengthen the skins of the tubers; providing better resistance to many diseases (black scurf, silver scurf and common and powdery scab) and also a better skin finish. Calcium deficiency also causes internal rust spot so it’s essential to apply calcium at the right time but also ensure the correct source of calcium is used. For example, liming materials won’t supply plant-available calcium to the crop therefore it won’t supply sufficient supply to meet the demand.
Magnesium is important during tuber bulking where it plays a major role in maintaining tuber quality and is therefore a key nutrient.
Micronutrients are also important to ensure the crop has all it needs to produce a good, quality yield. Zinc and manganese are key to help the crop’s defence against powdery and common scab as well as maintaining skin finish.
A lot of fertiliser has gone on in this last 10 days as temperatures have even reached the high teens! Due to a relatively warm, dry winter crops have been able to grow well through the season therefore could require higher rates of all nutrients due to their forward growth.
Hopefully with your first dose of nitrogen there was PK and S as well. Ensuring all nutrients are in sufficient supply is particularly important with how dry conditions are. Due to how dry last season was, coupled with the fact there has been much less winter rain fall, there is little water at depth. Soils are drying out very quickly and this is a problem at this early stage of growth. Making sure you have sufficient levels of potash will be key as K helps the plant’s water use efficiency and regulation. Phosphate will enable the plants to grow a good root system and scavenge what water is available.
The period of rapid growth in the spring is when, as a grower, you can influence the biomass of your crop. Biomass is key to a good yield therefore the higher the biomass the better. However there is a cut-off point, once the plant switches to reproductive phase where you can no longer influence the biomass – this is generally towards the 3rd week in March.
Ways you can influence this are early, higher rate applications of nitrogen as noted in previous articles – however most will have applied their first dressing by now. It is not too late however. Applying micronutrients will also help with building biomass and helping the plant utilise water efficiently.
Applications of micronutrients should be sooner rather than later, pre T0 or T0 is best for a lot of micronutrients to ensure sufficient supply during this rapid growth phase.
Weather-permitting, it won’t be long before nitrogen (and sulphur) will be going onto cereals and oilseed rape and is a high priority on farm. However have you thought about micronutrients at this time too?
Once crops start to go into the stem extension phase of growth they require a lot of nutrients to keep up with their rapid rate of change. This of course means the requirement for major nutrients increases but also the micronutrients as well. 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 major problems within the plant.
Particularly magnesium, which is part of the chlorophyll and therefore vital to efficient photosynthesis, 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 capture and therefore effect 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 will show you which micronutrients you will 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 on cereals and YaraVita Brassitrel Pro on oilseed. These products have the specific nutrients required for those crops and can be used to ‘cover all bases’ if tissue analysis isn’t for you.
As spring approaches it is important to think about your phosphate and potassium soil status to know what rates to apply. However irrespective of your indices some fresh P&K in the spring will benefit your crops with early availability.
With soil temperatures generally being low in mid-end of February the availability of nutrients from the soil is limited, particularly phosphate. An application of an NPKS grade at this first nitrogen timing is perfect for the plant as it starts growing before soils are warm enough for it to be able to utilise what nutrients might be there.
Phosphate is important in the spring and is necessary for energy transfer in the plant as well as root production; which is also essential during the rapid phase of growth in spring. Phosphate is almost completely immobile in the soil (P needs to be less than 1mm from the root before uptake can occur) and most of it is unavailable to the plant.
In this same spring period there is a high demand for potassium too, especially on cereals and oilseed. The demand for potash may be in excess of 20-27 kg P/ha/day (depending on the crop) with a total requirement of 575-700kg P by the end of flowering.
With growers taking P& K holidays they are depleting the soil without adding a maintenance dressing to ensure that the P&K the previous crops have removed has been replaced. Unless you are confident of the P&K availability in your soils this is a risky business as crop requirement is high.
In trials conducted on behalf of Yara, a fresh application of P&K in the spring gives a yield benefit. Use of a compound NPKS fertiliser, such as YaraMila Actyva S (16:6.6:12.4 + 2.6% S), supplies a uniform application of N, P and K as well as sulphur.
After winter the crop needs a quick spring wake-up in order to set the foundation for a good yield. When the crop starts to actively grow it produces new leaves and tillers and for every new leaf a new root also develops.
Typically 50-60% of above ground biomass is converted to grain yield (harvest index). A large root mass creates resilience to potential drought periods during the spring and summer months to come as well as ensuring maximum nutrient use efficiency. However the biomass growth time is limited as at a critical day length (approx. mid-March) the wheat plants will switch from vegetative to reproductive growth and therefore the potential biomass has been determined.
However it is not too late to influence this growth as decisions now around nitrogen source, rate and timing will influence the crop’s development. The nitrogen needs to be in a form that is immediately available to the crop for uptake, making sure the growth isn’t restricted. Nitrate nitrogen as in YaraBela Axan (27% N + 3.6% SO3) is immediately available whilst urea needs to undergo a biological transformation first from urea to ammonium and then to nitrate.
This transformation depends on certain factors such as soil temperature – soil temperatures early on in spring are usually low. At these temperatures the transformation of urea to ammonium will take around 4 days, whilst the next transformation from ammonium to nitrate could take over 6 weeks.
The best management decisions are well-informed ones and the greatest chance of survival comes from adaptation – now is the time to reflect on decisions that influence yield potential. Nitrate nitrogen fertilisers supply immediate, available nitrogen with minimal losses – producing highly efficient crops!
UK soils have changed a lot in the last few decades; whether it’s the 97% sulphur deficiency found in soils sampled or the low organic matters across arable land. Therefore everyone knows the importance of taking a soil sample; but should you be investing in more than just basic soil analysis?
The basic analysis will give you P, K, Mg and pH; which is a good start but what about Ca, S, Mn, Cu, B, Zn, Mo and Fe? All are important to plant nutrition and you may be unaware that your soils are low in one or more of these elements. Soil sampling is about finding the limiting factors on your farm and being able to make sure they aren’t impacting upon yield – think Liebig’s barrel!
Yara Analytical Services have processed over 20 million samples. This huge dataset has shown that after removing all the soils with limiting factors such as P < index 2, pH <6.5 and micronutrient deficiencies then less than 20% of UK arable soils growing wheat have sufficient levels. When you look at soils sent in for oilseed rape fields then even less are sufficient.
By taking a broad spectrum soil sample you’ll know about these issues before it’s too late – when symptoms appear and yield is already taking a hit. Liebig’s law of the minimum states “A deficiency of any single nutrient is enough to limit yield”. With yields being pushed further, whilst costs savings are sought (such as P and K holidays) you could be limiting the effectiveness of any increased nitrogen applications.
Using tools to work out how much nitrogen to put on your crop makes things easier during a busy time of year. If we think about Yara’s N-Tester then it can be used to monitor the nitrogen levels in the crop throughout the season or it can be used at the last timing to take the guesswork out of that final dressing.
The N-Tester works by measuring light through the chosen leaf which correlates to the amount of chlorophyll (and hence nitrogen) in the leaf at that time. The device can then tell the user how much nitrogen it recommends to apply to get the plant up to optimum levels. This means you can fine tune applications For example you wouldn’t know how much the plant has taken up through mineralisation therefore the N-Tester enables you to fine tune later applications.
N-Tester can be used throughout the season to see how much nitrogen is in the crop and therefore also shows when levels are dropping and a new application is required – the crop tells you when it needs nitrogen rather than you having to decide.
Yara is launching 2 new versions of the N-Tester this year: one is similar to the older version but connects to a smartphone/tablet via Bluetooth therefore is a lot easier to use and has GPS of all readings taken. The other version clips onto your phone’s camera and pictures are taken to get a nitrogen recommendation.
Both of these devices will be supported by the Yara Irix app which will also encompass Yara’s ImageIT app for nitrogen decision making in the spring.
I have written before about the importance of applying boron to both oilseed rape and cereals. However Yara Analytical Services (YAS) data shows that many crops are still deficient in boron throughout the spring and anecdotal evidence also shows that people just aren’t applying this important micronutrient.
The term micronutrient doesn’t mean that those in that category are any less important than the macronutrients, merely that they are required in smaller amounts by plants. Boron itself is particularly important for pollen formation and viability hence why most growers would see it as important for flowering oilseed crops – over 50% of samples sent in to YAS this spring were deficient.
It is equally important for cereals crops too but even fewer applications are made to wheat and barley. Boron has an important role in grain set in cereals and therefore has an effect on grain numbers per ear.
Trials work conducted by Yara showed that an application of boron at the T3 timing gave a yield benefit of between 0.15 – 0.17t/ha. When you think of the cost of an application of 1.0L of YaraVita Bortrac being about £1/ha then the ROI is 25:1! This sounds too good to be true but just shows that there really is no excuse for applying boron to both cereals and oilseed crops.
Sulphur is an important nutrient for all crops, it is the precursor to proteins which are of course the building blocks of yield.
Due to lack of sulphur from atmospheric deposition (0-3kg S/ha/year) there is a shortfall which can be filled with organic manures and of course mineral fertiliser. Organic manures have an inconsistent amount sulphur therefore tend to cause more variability across a field. Also they are applied in the autumn or early spring when the crop isn’t able to utilise the sulphur fraction.
Even though the importance of sulphur is well known, there are still growers who don’t apply any. The relationship between sulphur and nitrogen is a close one, with several processes within the plant requiring both nutrients to work efficiently. If you are trying to increase your nitrogen use efficiency then having an adequate supply of sulphur is a must.
Sulphur, like nitrogen, leaches readily from the soil so the source and the time you apply it is as important as the amount. Applying your sulphur as you would nitrogen, split between at least 2 or 3 applications means that the sulphur is less likely to be lost (via leaching) before being taken up by the plant.
When it comes to timing then applying sulphur in the autumn is a no-no. Due to winter rainfall the likelihood of that sulphur being there in the spring is minimal. Therefore applications should be in the spring, along with nitrogen using an NS or NPKS product. YaraBela Axan (27%N + 3.6%S) contains calcium sulphate which is highly soluble and therefore reaches the roots quickly.
From Yara trials, sulphur gives an average yield benefit of 0.85t/ha for wheat which at November prices for gives a ROI of 4.6:1. For oilseed rape the yield benefit is 0.5t/ha giving an ROI of 3.5:1.
The government, this year, released a document called the ‘Clean Air Strategy’ which outlined the current situation on emissions in the UK and the impact these have on human health and the environment.
Air quality is now thought to be the largest health risk to the UK and linked to issues with human health, in particular to cardiovascular and respiratory diseases. This of course puts more strain on the NHS and it is estimated to cost up to £18.6 billion by 2035 to treat such diseases.
The document outlines various areas that are the main sources of emissions – Transport, Industry, Home and Agriculture. Out of all ammonia emissions, agriculture is held accountable for 88% of them (2016). Out of this 88% then ¾ comes from organic fertilisers, livestock and AD and the remaining ¼ comes from fertiliser use. The government hopes to reduce these emissions by 8% by 2020 and 16% by 2030.
If we focus on the emissions from fertiliser then urea is the main source of the ammonia emissions. The government has outlined three ways in which these emissions can be reduced:
The use of urea will be regulated by 2020 using the methods outlined above. There is also mention of reducing nitrogen limits (further advice from a panel of experts has been sought so there isn’t further information on this currently) and mandatory use of a nutrient management plan.
Therefore it is important to be aware of these changes as they will impact on most farming businesses in some way or another.
Now is a great time to take soil samples post-harvest in order to see what you’ve got left in the soil after the previous crop. For many, a basic soil sample will be taken which will give you P, K, Mg and pH which is a good starting point but what about all the other nutrients that are in there?
The importance of P and K at crop establishment is well documented and most growers would be aware of this but Ca, S, Mn, Cu, B, Zn, Mo and Fe are all important nutrients too and you may be unaware that your soils are low in one or more of these elements. Attention to detail is the key to success; which has been proved by many growers, including the entries into the Yield Enhancement Network (YEN).
By taking a broad spectrum soil sample you’ll know about these issues before it’s too late – when symptoms appear the yield is already taking a hit. Remember Liebig’s law of the minimum which states “A deficiency of any single nutrient is enough to limit yield”. With yields being pushed further, whilst costs savings are sought (such as P and K holidays) you could be limiting the effectiveness of any increased nitrogen applications.
If a broad spectrum soil test isn’t for you then think about applying a multi-nutrient spray in the autumn such as YaraVita Brassitrel Pro to cover yourself against potentially unseen deficiencies and follow up with a tissue test in the spring to catch any that might require an additional top up such as Mg or Mn.
Getting oilseed rape established quickly is key in the fight against autumn pests and diseases. I have mentioned in previous columns that placing a starter fertiliser can make a difference to getting that crop off to a good start but micronutrients also have an important part to play.
Soils in some places are still relatively dry in the top layer, OSR roots aren’t able to grow through solid soil very well and tend to curl up rather than penetrate through. Where there is enough moisture then it’s important to look after the newly established plant and micronutrients play an important role at this autumn timing.
YaraVita Brassitrel Pro is a crop specific combination of several nutrients that are important for oilseed both in the autumn and spring. This product is a precaution for potential micronutrient deficiencies before they start to show symptoms; as once this occurs then yield is already being lost.
Recent Yara trial data from the 2018 harvest has shown an average yield benefit of 0.46t/ha from an application of YaraVita Brassitrel Pro in the autumn and the spring. At Ex farm prices of £320/t this yield benefit would give you an extra £147/ha with a ROI of about 4:1 from the two applications.