Wheat crop at Revesby Estate © Revesby

Lessons learned from a technology trial are being rolled out across the rest of the cropping area on one Lincolnshire Estate, as part of an ongoing drive to improve nitrogen use efficiency.

The changes could be worth more than £24,000/year across the whole winter wheat area.

Revesby Estate is one of the four Digital Technology Farms (DTFs) established by agronomy firm Agrii to assess how new technologies can be combined to best effect and integrate into existing farm practices.

See also: How new technology enables yield mapping for root crops

In the first year, one 40ha field of winter wheat was split into two halves. One half was managed by Revesby Estate’s farm manager Peter Cartwright using his standard practice for fertiliser and fungicides.

The other half was managed by Agrii’s technology trials manager, Jonathan Trotter, and UK digital agronomy development manager Lucy Cottingham, and guided by live data from the potential “farm of tomorrow”. 

They focused on crop nutrition (applications and timing), nitrogen use efficiency, and fungicide application timing and choice. Then at the end of the season, they carried out a cost benefit analysis.

Jonathan Trotter (left) and Peter Cartwright © Agrii

Season one lessons

In year one, the DTF half had an average of £8.65/ha lower input cost, but the wheat yield was 1t/ha lower than the farm standard resulting in a lower gross margin.

Jonathan explains that the lower yield was down to the differences in fungicide choice, with the DTF programme being less effective than the farm standard.

“While it controlled disease effectively according to leaf layer assessments through the season, it didn’t add other benefits such as greening or other physiological benefits to the same degree as the farm’s approach.”

This was backed up by the earlier senescence being observed on DTF side.

Looking at zone E (no fertiliser), the fungicide strategy added 2.83t/ha to overall farm yield. But for the DTF side, the fungicide strategy added 1.6t/ha to overall yield, with a difference of 1.23t/ha.

The farm strategy included Syngenta’s new fungicide pydiflumetofen (Miravis Plus), whereas the DTF side did not include this active.

Other Agrii trial results have shown that using pydiflumetofen adds 1t/ha to average yields compared to areas where it has not been applied.

Nitrogen use efficiency

Looking at nitrogen use efficiency, both halves averaged 48% even with the DTF yield being more than 1t/ha lower than the farm approach. But on the DTF side, this was achieved by spending less (6-24% for the different zones), Jonathan suggests this makes their approach more sustainable.

In the zero-fungicide zone (where nitrogen was the only treatment difference), the nitrogen use efficiency was 43% on the DTF half – better than the 33% on the farm standard side.

Therefore, the DTF nitrogen strategy was, on average, £33.91/ha more effective than the farm standard approach.

Jonathan calculates that across the 400ha of wheat at Revesby, it adds up to £13,564 in savings, with an extra £10,500 in Sustainable Finance Incentive (SFI) payments (for variable rate nutrition), bringing a total benefit of £24,064.

Changes at Revesby

Drone © Agrii

With this potential saving, Peter has rolled out the variable rate nutrition approach across the estate and will be using the Skippy Scout drone artificial intelligence (AI) software together with Contour (Agrii’s precision farming mapping tool).

He has also signed up to the SFI variable rate application of nutrients option (PRF1), which is on top of existing options such as no-till farming (SOH1).

“The payment for variable rate nutrition plus direct drilling equates to £100/ha, which is a worthwhile income for something you are already doing,” says Peter.

Other farm changes

This year, Peter is also carrying out some nitrogen response work to get a better handle on crop responses. He explains this was prompted by grain protein analysis, which suggests crops are possibly being underfed N.

“Grain protein percentages are in the high 9s and low 10s, so not optimal for feed wheat.” Therefore, he is increasing overall rates to 240kg/ha for wheat in 2025 from the current 220kg/ha.

Another area Peter is looking at is a urease and nitrification stabiliser for liquid fertiliser.

In an ideal world, he would opt for a little-but-often approach, but sprayer capacity means it would have to be solid fertiliser and that would require more labour.

“Having someone on the spreader and another on the loader to do solid spreading is just not practical for us.”

Instead, the estate applies liquid nitrogen in two splits. The first is in February, which is a quieter time for the sprayer, and the second application is made in late March, before the T1 sprays.

This season’s plans

Jonathan says reflecting on the first year results, they had put too much emphasis on technology and not enough on a combination of the agronomy and technology.

So this year, they will readdress the balance by introducing some new technologies and combining this with the latest in agronomic innovation.

Lucy says this will include Bayer’s CropCheck testing of leaves for latent septoria and yellow rust levels to help with fungicide decisions. In addition, the Australian BioScout spore tester will be used to monitor the airborne disease risk.

The Contour Disease Risk forecast will also be tested again, adding to last year’s experience.

Peter says there is still a lot to learn with the disease alerts. “If you get a red light, do you go and spray or wait for two or three days of consecutive red alerts. More work is needed to determine how to use these alerts and give us the confidence to act on them.”

The DTF trial at Revesby is also being expanded into other crops including oilseed rape, where they will be looking at nitrogen, fungicides and desiccation.

Disease and fertiliser strategies 2024 in detail

FieldMate weather station © Agrii

Starting with disease, Lucy Cottingham explains that they deployed the Dutch FieldMate in-field weather station and SmartFarm app to monitor the climatic conditions and determine the in season disease risk.

This information was combined with observations from walking crops to make fungicide recommendations (product and timing).

Recalling the season, there was no T0 fungicide applied in either half of the field due to the lower disease risk and anticipated yield potential. The variety, Highgrove, also has good resistance ratings for yellow rust (9), brown rust (6) and septoria (6.5).

The whole field received a nutrient growth promoter and, at the T0.5 timing, Agrii opted for an innocul8 (see “Treatments” table) to help trigger the plant’s defenses as a protectant.

However, Peter says yellow rust and septoria are the key diseases at the estate and he went hard at T1 to knock the yellow rust opting for Velogy Plus (benzovindiflupyr) + Soratel (prothioconazole).

But with disease pressure remaining low and FieldMate largely generating green lights for septoria and rusts, Lucy and Jonathan opted for a sulphur-based biofungicide plus mineral mix.

By T2, there was some disease bubbling with brown rust and septoria both being seen and Peter went hard with his two-pronged approach using the new SDHI fungicide Miravis with prothioconazole to tackle the rust and septoria threat.

On the tech side, the low level of septoria and brown rust meant they opted for azole, strobilurin and SDHI mix. Finally at T3, the whole field received straight tebuconazole.

Nitrogen

Moving to nitrogen, on the tech side, the Skippy Scout drone and software were used to generate detailed green area index (GAI) maps for all soil zones. This combined with the Rhiza satellite NDVI data to produce an application map for each timing.

Fertiliser rates were calculated using a target yield of 10t/ha and 11% protein along with baseline soil mineral nitrogen results taken in February. Drone flights were carried out on 12 February, 18 March and 17 April.

For the first application, the GAI ranged from 0.37 to 0.8. Consequently, fertiliser applications varied from 53kg/ha to 80kg/ha compared with a flat rate of 110t/ha for the farm standard, she says.

The second application saw the farm standard receive the other 110kg/ha split and the technology side had just two rates – 103kg/ha and 124kg/ha.

Jonathan adds that periodic tissue testing confirmed crops were not short of nitrogen at all sampling points across the field after both applications.

Source: Agrii

Source: Agrii