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An asset of the Climate FieldView is the ability for growers to organise and manage on-farm trials at levels not seen before.

Regardless of size and shape, plot or area boundaries are logged in the platform making identification of field trial areas simple. And with the ability to overlay yield data with variable rate information across these area makes accurate data interpretation simple too.

It was primarily these two attributes that drove a number of growers to choose FieldView for variable rate N evaluation in WOSR.

The three, Simon Gent of Stocksbridge and Tom Monk of Rookley Farm both in Hampshire, and Rob Burden of Chilbridge Farm, Dorset and have slightly deferent reasons for WOSR in their rotation, but all want to achieve greater field evenness via the 3.5 GAI flowering target.

The 3.5 GAI target is the optimum for light inception into the canopy but it is tricky to achieve given that pests and pigeons have a liking for the crop.

ADAS crop physiology manager, Dr Peter Berry says big canopies might look the business but don’t always deliver the goods. This is because their thick flower layer reflects light and restricts photosynthesis and seed set. “The ideal is 3.5 GAI as this allows light to penetrate the lower canopy. To achieve each unit of GAI the plant needs to take up 50 kg N/ha and nitrogen is the most effective way to manage canopy structure along with PGRs.”

Yara’s Natalie Wood agrees but points out the alternative risk of insufficient nutrition to try and minimise growth - and therefore lodging. Her view is growers need to make sure the crop has everything it needs to prevent yield-loss and then back it up with a robust PGR programme.

She points out OSR is a particularly large, fleshy crop which therefore requires a good level of nutrition, especially during the rapid growth phase in the spring with N and S particularly important. “Sulphur can easily be mistaken as nitrogen deficiency because the symptoms are similar. If the crop doesn’t have enough sulphur then it can’t take up nitrogen effectively or efficiently, therefore a lack in sulphur can lead to nitrogen uptake being hindered. OSR, in particular, requires quite a lot of sulphur at 75-100kg SO3.”

Rob Burden of Chilbridge Farm, Dorset has put aside an entire field of Campus for his OSR N trial. He is varying rates by as much as 40% due to significant variations in biomass.

He will be applying total rates of between 140 – 280 kg/N/ha with a control strip of 230 kg/N/ha. The reason for the diversity of rates is that vegetative images captured on 28th February revealed significant biomass in some field areas.

As well as the trial targeting better crop uniformity, he also considering extending the trial to look at reduced rates with further applications on thinner ground. The aim here is to see whether poorer parts of land would deliver better margins with less N applied. “I don’t want to be spending good money after bad. If yield potential is already capped then there is no point in applying high volumes of fertiliser.”

Mr Burden has always believed in the value of variable rate with OSR crops but without digital data capture there was always a question mark hanging over the quality of the data. “Without combine yield monitoring, evaluation was really down to visual inspection of crops through the season. It gave me an idea but not much more.

“And even with combine yield monitoring accurately overlaying yield data with variable rate mapping wasn’t really possible. But Climate FieldView changes that and allows me to do this even with small or irregular field areas.”

With a ryegrass problem on the farm, early harvesting OSR ensures more time to prepare ground for winter wheat. But he considers OSR is more than a rotational crop with good yield potential if CSFB can be managed.

This season he had some field areas up to his knees by early March. A good dose of pig slurry helped ahead of drilling but so did a modified Stocks seeder.

He built his own frame and boom as he had concerns about broadcasting seed evenly. The advantage is the ability to cover a large area quickly. “It is a low disturbance system where we put the seed on and then rake and roll it. The improved efficiency this season allowed us to drill ahead of rain being forecast and avoid periods of CSFB movement. This and better seed/soil contact helped get crops up and away quickly, important as aphicides are no longer effective.”

With first dressing applied - 80 kg/N/ha to the control strip with sulphur being applied as kieserite – the question is now the number of further dressing. In the past that has been a single application as late as he can go. This will probably be dictated by satellite biomass imaging.

For further applications he makes the switch to liquid fertiliser to apply accurately across a crop as high as OSR. Experience has taught him that late applications deliver a yield improvement but research has indicated improvements in oil content.

Simon Gent is already applying variable rate N via SOYL biomass imaging but he feels FieldView refines this further. “It’s the precision with FieldView that I like. Other platforms have similar mapping and vegetative imaging properties but area boundaries and the data interpretation functionality are very precise. There’s no need for unsightly canes in a field!”

He is varying rates by plus or minus 20% based on soil condition compared to the control plot of 220 kg/N/ha. “We have a lot of undulating terrain here and our better soil gets washed down to lower levels, with higher ground being more a mixture of chalk, flint and stone. If I can improve crop evenness across the highly variable fields, I’m likely to see an overall gain in yield,” he notes.

The first dressings were undertaken in late February with the control plot getting 60 kg/N/ha. But uptake depends on numerous factors, soil condition being one of them and could impair the 175 kg N/ha to achieve the 3.5 GAI target.

Normally the remainder would be applied in a single application but this season he is also evaluating the value of extending the number of dressings. “The data coming back from the Yield Enhancement Network (YEN) is showing the benefit of spreading fertiliser applications. This suggests that feeding the seed is as important as feeding plant tissue. I will be saving approximately 40% of the total dose to as late as possible.”

Natalie says the ‘little and often’ approach works for many nutrients, such as N, S, P and K. “We have trials each year looking at different N sources (33.5%, UAN, Urea etc) and we always have an NPKS product applied all the way through as well.

“So far this has consistently proved to be the best yielding regardless of the season. In our OSR trials it was just 2 applications, at the end of February and stem extension. YEN results have also highlighted that more N splits can give a yield benefit. However, that has to be considered against farm resource and time management - it is what works best given a number of considerations.”

A particular concern this season are trace element shortages. Tissue testing has revealed insufficient boron, copper and molybdenum. 

Until recently N has been applied at a flat rate at Rookley Farm, Hampshire. Last season this was a total of 255 kg/N/ha over five splits through September to April.

Mr Monk is also using a whole field for his trial. Two 32m tramlines through the middle will get a flat rate of treatment of around 250 kg/N/ha with variances of plus or minus 20% for the rest based on field health images obtained via the platform’s field health tools.

He also prefers the ‘little and often’ approach to keep the crop fed, so some of the variation in rates will be as small as 10 kg/N/ha on each application. “The benefit with FieldView is recording all prescriptive, biomass and yield data precisely across the areas concerned, so there will be no ambiguity about the results.”

As well as the N trial he is planning to test two different drilling strategies to combat CSFB. Having acquired a Weaving direct drill for autumn 2020 drilling, he will compare drilling directly into wheat stubbles with his current more conventional approach. “We can’t go down the companion cropping route with seed crops and chemical control isn’t particularly effective.

“Research has suggested that beetles are attracted to bare earth so stubble is a potential deterrent. If we can trick the beetles and conserve some moisture hopefully the crop will have a fighting chance of getting away and resisting beetle attacks.”

That will be extended further in the autumn of 2021. A newly purchased Claydon drill can be used either as a minimal soil disturbance option like the Weaving, or with a leading tine, more aligned with a strip till system.  The aim to cause some disturbance but not as much as a conventional drill set-up.

He also expects to continue with the N trial as he sees one season’s worth of data as useful, but not complete. “Every season is different and last year we applied a little boost of N in January to give crops a hand. But it hasn’t been needed this season as with better conditions. But I want to build several seasons of data so that this knowledge can be used to meet the specific situation faced,” he concludes.


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