Crop Nutrition seminar

While there is a need for more climate-friendly fertiliser regimes, productivity and fertiliser efficiency remain key to profitable farming.

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Crop nutrition


Prof Roger Sylvester Bradley, ADAS Head of Crop Performance

Nutrient management strategies have hitherto focused on building soil fertility and health, then trusting that national recommendations and nutrient products work.

With increasingly urgent economic and environmental pressures, and evidence of widespread nutrient deficiencies, analysing crop nutrients at harvest and benchmarking the results could be vital extra tools in recognising local peculiarities and maximising each crop’s output and efficiency.

In the increasingly uncertain but ever interconnected world of 2020, collecting and sharing field-specific data can support better nutritional decision-making. It can also build towards better fertiliser guidelines.

Phil Jarvis, Farm Manager, The Allerton Project (GWCT)

While farming’s role in greenhouse gas emissions is widely acknowledged it is not well understood.

What is being done to help growers better understand how to reduce their greenhouse gas emissions and to sequester carbon in their soils? Where do they start on the journey to net zero and what are the practical steps they can take now?

Anke Kwast, Vice-president of the Climate Neutrality Roadmap

Yara is working towards making carbon-free fertiliser and renewable hydrogen is the major enabler for the manufacture of CO2-free or ‘green’ ammonia, which in turn is the key ingredient for ‘green’ fertiliser.

Why is ‘green ammonia’ important for the future of British farming? What particular issues or challenges will it help farmers address? What might surprise farmers about it? What are Yara’s current plans and timescales with regards to green ammonia?

Attendees watching live got to ask the experts their questions, find them below!

Mark Tucker – first products anticipated within 5 years.

Anke Kwast – we will have green fertilizers from 2024 onwards. The green fertilizer will be 2 times to 5 times more expensive.

Mark Tucker – The increased cost is currently high so needs sharing across the supply chain. As we know green energy is getting cheaper so hopefully the gap will close.

Mark Tucker – the same, as it is still nitrate. The in field emissions have to be managed at the same time through improving NUE

Mark Tucker – crop offtake is a combination of yield and grain analysis rather than using standard book values

Roger Sylvester-Bradley – The YEN Nutrition Benchmark report (Report-2) is generated for each year. So, this should help to capture seasonal vacancies.

Roger Sylvester-Bradley – yes we have looked at this in YEN data and find that the relationships are weak … which means that crop capture systems are not always as good as we would wish … so grain analysis tells us whether the capture system is working.

Roger Sylvester-Bradley – Yes .. grain analysis evidently provides the ‘proof of the pudding’ but soil analysis and leaf analysis can still do the jobs that they have always done

Phil Jarvis – Yes, much more difficult for those growing roots and veg. Especially for crops under the ground. One or two strip till approaches for sugar beet. As I eluded to at the beginning of my presentation there will be other areas where such businesses can have an impact on GHG

Mark Tucker – as we move into having to improve soil health / quality then we can only know the outcome of changes we introduce by defining our starting point – hence when taking soil samples get as much information from that sample as possible – pH, OM, sand, silt, clay etc.

Phil Jarvis – relationships between texture and OM will throw up some interesting observations around what a sustainable organic matter level is. We haven’t cracked what is the most consistent and accurate OM test either. And remember the more biologically active a soil is, it is more likely to emit GHG and ‘eat’ its OM. So will need to look better research on how we get to such a balance.

Roger Sylvester-Bradley – organic matter and texture may help in explaining nutrient supply and capture but they are very indirect tools … the direct answer comes from nutrient analysis

Roger Sylvester-Bradley – the most important nutrient in straw is potassium. we are starting to look at this in Cereal YEN this year. K% will have to differ quite a lot to justify spending another £40 per field on analysis.

Phil Jarvis – We do both DUMAS and Loss on Ignition. As stated earlier, the difficulty is reliable sampling repetition.

Anke Kwast – yes, there are guidelines around optimum carbon contents of soil, this depends on the soil texture, the cropping system and the climate. Yara MegaLab is offering a soil health test as a pilot project to develop a suitable analysis and guidance around this. As a rule of thump , Within such a system it can be increased by about 10 % versus given carbon content depending on soil management

Mark Tucker – each soil / field will at some point get to a steady state by way of OM%. A guide is 3-4% (Dumas test). What we know is that as OM% increases then nutrient availability improves – Rothamstead research from 30 plus years ago. Can then look to operate at a lower soil index

Roger Sylvester-Bradley – Yes indeed … and I think we now have the tools to do the necessary tests

Mark Tucker – re TSP/DAP – these are all orthophosphate so the lock up still an issue following their application. Might be worth your while looking more at the timing and type to include products with polyphosphate and DCP in them.

Phil Jarvis – I would look at SOM in three bands 1. Those under 3%. 2. Those between 3-6%. 3. Those above 6%. The challenge is to get your soils into a higher band. I do also accept that some lighter sandier soils will have some real issues hanging on to their SOM.

Mark Tucker – they are high levels and yes could pose other issues that we see when farming on ‘black’ soils. High values certainly will be seen in the top layers as a move to zero till, but this may not mean an overall gain in the full profile. The analysis used also needs considering as some cheaper analysis can give misleading values – Dumas combustion will give the most accurate


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