Expert shares advice on autumn nutrition for OSR and winter cereals 

Over the last 70 years, there have been huge incremental increases in yields of crops like winter wheat due to changes in farming practices, such as the adoption of nitrogen fertilisers and advancements in plant breeding and genetics.  

But over the past two decades, yield appears to have plateaued, apart from a few high-yielding years in 2015 and 2019. Limiting factors like poor weather conditions and disease play a part, and so does nutrition.  

It is well known that even if growers are getting everything else right, a deficiency in even one essential nutrient can reduce the potential yield they’ll get from that crop.  

Chris Harrold, Yara’s head of crop nutrition agronomy for the UK and Ireland, has shared some pointers on autumn nutrition for OSR and winter cereals, including what to consider and the testing that growers should be doing to improve yields and get the most from their inputs. 

The importance of analysis  

Mr Harrold said: “It’s really important that growers have a good understanding of the base they’re working with so they can make the most of their inputs.  

“I would always encourage them to do more than the basics with soil sampling, so as well as testing phosphorus, potassium, magnesium and pH, they should expand the analysis to include organic matter, and micronutrient content, and assess the physical and biological status of their soil.” 

Alongside soil analysis, carrying out leaf tissue analysis throughout the growing season gives growers the opportunity to monitor crop health and correct any deficiencies that testing flags up.  

This is important, as deficiency is not always visible in the field. Agronomists refer to this as the ‘hidden hunger gap,’ the period of time where crops aren’t getting enough nutrients, but they don’t show any signs of deficiency, the expert explained. 

Grain analysis for specific weight and protein content is nothing new, though there is an increasing demand for grain analysis for phosphate and potash.  

Recent research has found that there are critical levels for these elements within the grain, and understanding how much the crop has taken up can help growers plan their nutrient inputs for the coming season.  

“When you look at winter wheat uptake of macro and secondary nutrients, we’re talking about tens if not hundreds of kilogrammes of nutrients, so if growers know what the crop has actually utilised in that season, they need to make sure they rebalance that uptake through the rest of the growing season,” Mr Harrold added. 

OSR autumn nutrition 

Oil seed rape has had its fair share of challenges in recent years, and this is reflected in the decline in the number of growers who are choosing to grow the crop.  

Estimates say that the national acreage of OSR over the coming year is expected to be around 200-250,000 hectares, a third of its 2012 peak.  

Since the removal of seed treatments, flea beetle has been a real challenge for growers, and weather conditions have affected crop establishment.  

Yara’s head of crop nutrition agronomy said that for OSR growers who want a healthy, resilient crop, the aim of autumn crop nutrition is ensuring crops have enough essential nutrients to aid establishment through the winter months prior to leaf and floral initiation.  

Magnesium, boron, molybdenum, and phosphorus are all crucial. While many growers will have used some form of seed bed nutrition, for growers who haven’t been able to apply any due to later establishment, an application of a foliar phosphate product is recommended to encourage rooting.  

Yara recommends applying YaraVita MAGPHOS K at 3 to 5 litres/ha at growth stage 14, perhaps along with a volunteer cereal herbicide.  

Tissue analysis will help growers understand whether the crop would benefit from some foliar nutrition in the autumn to ensure it has a sufficient supply of key nutrients throughout the growing period.  

Mr Harrold continued: “There are two key reasons to consider using some autumn foliar nutrition this year. Firstly, it provides those nutrients straight into the plant to maintain crop growth and improves winter hardiness, and secondly, you’re loading the crop up with nutrients ready for spring growth.” 

A little later, at the four to eight true leaf stage, it’s advised that growers apply YaraVita BRASSITREL PRO at 3 litres/ha to maintain nutrient balance and optimise yield. This can be done at the same time as fungicide and propyzamide applications, however, there’s a caveat. BRASSITREL PRO, while widely tank mixable, has a very different pH level to MAGPHOS K, so these products should be applied at separate times.  

Autumn nutrition for winter cereals 

With winter cereals, the approach to autumn nutrition is similar to OSR. Growers should start by thinking about what is needed in those key growth stages.  

The focus should be on the foundation stage, getting the crop established through good rooting and tillering, and achieving optimum nutrient use efficiency to maximise yield, the expert added.

During the pre-winter period, it is essential to get key nutrients like manganese and zinc into the crop. Both play a crucial role in crop health.  

They are important for the production of chlorophyll and therefore photosynthesis, and manganese also encourages root health, increasing the resistance to root-infecting pathogens. Manganese deficiency is something growers should remedy as soon as possible.  

“If growers have issues with manganese, I’d recommend that they don’t delay treating it. We know that certain soil types and certain areas within fields tend to have manganese deficiency, and this can cause the loss of biomass. Once this happens, growers won’t be able to get it back,” Mr Harrold advises.  

Yara recommends growers apply YaraVita Mantrac Pro, a suspension concentrate of manganese that provides a long-lasting feeding effect to correct deficiency. Previous trial work has shown that applications of MANTRAC Pro in the autumn and spring as opposed to just the spring resulted in a higher yield.  

Create a nutrition plan 

As zinc is also crucial for winter cereal crop development as well as improving tolerance to winter weather, growers could also consider extra applications in the autumn. YaraVita AMAZINC provides a high concentration of both manganese and zinc, and it’s widely tank mixable.  

Growers looking to boost rooting and early tillering and overcome any issues with pH or soil temperature-related phosphate availability in the soil, should consider an application of YaraVita CROP BOOST, a highly concentrated foliar phosphate fertiliser.  

Again, growers should take care not to mix MANTRAC PRO or AMAZINC with CROP BOOST due to the difference in the pH in their formulations.  

For growers looking ahead to putting their nutrient management plans together for the spring, Yara has a free digital tool, AtFarm, that can help. The app has been designed to be a simple ‘one stop shop’ where growers can do everything from monitoring crop growth using satellite imagery, to planning crop nutrition, and managing nitrogen applications.  

“Growers can create a nutrition plan, based on the field and crop parameters they enter. While this involves a little bit of work, what they get in return is an exact nutrient amount calculated for the crop through the whole crop cycle. It even breaks it down to specific advice for each growth stage, which will allow them to optimise fertiliser use. Growers are also able to track soil fertility over time, which allows them to fine tune their nutrition plan throughout the growing season,” Mr Harrold concluded. 

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