How grower varies seed rates and N to lift whole-field output

Wiltshire farmer Matt Fry is using variable seed rates and nitrogen to help maximise returns from each hectare of cropping.

Farming 1,600ha of different soil types, ranging from heavy clay to light chalk, Matt aims to set crops up right from the start.

A tailored approach to seed and nitrogen is key to achieving this. He says the two work seamlessly together and he wouldn’t use one without the other.

“Because our soils are so variable across the Wiltshire Downs, we put a lot of thought into soil mapping and seed rates,” says Matt.

Seed sets crop potential from day one and variable-rate nitrogen only works properly when variable seed is aligned, he says.

See also: N-fixing bacteria cuts cost and lifts yield for Cambs growers

Increase whole-field output

The goal is to even-up crop performance, increasing whole-field output and profitability.

“We want to pull our averages up. We don’t just want to farm more hectares; we want to produce more from each hectare,” explains Matt.

So far, this strategy has delivered clear results. Winter wheat yields now regularly achieve 11-13t/ha, up from the previous average of 10t/ha, all while using mostly the same varieties.

Matt mentions one example, a block of Crusoe wheat grown after maize that yielded 11t/ha and achieved full milling spec.

About 500ha of winter wheat is grown at Totterdale Farm, predominantly Group 1 and Group 2 milling varieties including the likes of Graham, Crusoe, Skyfall and Vibe.

“For harvest 2025, we topped out at 11t/ha which we were very pleased with, given rainfall was the limiting factor. Our best result over the last few years has been 13t/ha,” he says.

Extracting the value of data

Across the farm, seed rates are carefully adjusted depending on soil type, soil conductivity, drill date and blackgrass pressure.

Nitrogen rates tend to be pulled back in valleys and fertile flat lands, with rates upped strategically across the chalk uplands, which respond positively.

However, it’s all well and good having the data, but how it is applied in practice is a different matter. Will it bring a cost saving or output increase, or perhaps both?

Key to extracting this value, is having everybody in the farm team on board, says Matt.

“It’s important all the farm staff are bought into the system and understand the technology. We also need backup from the dealer,” he says.

The farm operates the Agrii Contour platform, where satellite imagery and agronomic data is layered together to guide both seed and fertiliser decisions.

Soil conductivity analysis carried out by Agrii’s Rhiza initiative is fed into the platform. The corresponding maps are remotely sent from the farm office to the fleet of John Deere tractors.

“We’ve had this system in place for three years and it’s been game changing. Before, we would manually import the data from a memory stick into the tractor.

“We seemed to always be travelling on the road transporting data. This has made things a lot simpler,” says Matt.

Seed plan

When it comes to the soil conductivity analysis, higher conductivity indicates higher clay content. Matt and his agronomist Roy Willis tend to increase seed rates here to improve crop competitiveness and establishment.

On chalk soils with low conductivity seed rates are reduced. Lighter soils have less water-holding capacity, so reduced rates help avoid over-competition and stress during drought conditions.

However, the maps need validating as this depends on the context of the field, weather and the season. Only then are seed rates tweaked up or down – something which can be flipped either way depending on the year.

George Fry, Matt Fry and Roy Willis © MAG/Emma Gillbard

“In a dry year, darker, more homogeneous soils often have a lower seed rate, but in wetter and stickier conditions these rates could be increased,” says Matt.

“The maps cannot be used in isolation and must be taken into context, which is why we work so closely with our agronomist.”

Winter wheat seed rates have a 12% range. Roy explains: “Early drilling in October is between 280 and 340 seeds/sq m. Later drilling in November onwards is between 350 and 400 seeds/sq m.

“If we know there is an area with high blackgrass pressure on wet clay soils, or there is a risk of slugs, we increase the rate so crops are competitive,” he says.

This approach creates a more even plant population across the field. Crucially, it determines how the crop will respond to nutrition later in the season.

Nitrogen

Nitrogen is typically applied to milling wheats at 250-300kg of N/ha, in a four- or five-way split.

Matt moved away from applying big lumps of nitrogen in favour of a little-and-often approach.

After setting up a “challenge” field in 2021, assessing the impact of splitting fertiliser into smaller, more frequent passes, Matt decided to roll out the approach across the whole farm. He hasn’t looked back.

Using NDVI imagery shows that nitrogen rates typically vary between 45-90kg N/ha, which has proved beneficial.

Matt’s son George, 22. has been home on the farm working for four years. This season he has been applying variable-rate fertiliser to crops and enjoys using the technology to target inputs to crop requirements.

George Fry © MAG/Emma Gillbard

Why one doesn’t work without the other

Variable nitrogen assumes crop potential varies across the field, but that potential is heavily influenced by how the crop was established in the first place.

If seed rates are not tailored to specific soil or seasonal conditions, plant populations are at risk of being uneven. 

If nitrogen is not adjusted, even a perfectly established crop will not reach its potential. High-potential areas may be underfed, or weaker zones may receive more nitrogen than they need.

By aligning both, Matt aims to optimise plant growth across the field, with populations selected for each soil type and nitrogen inputs matched to realistic yield potential.

The result is a more uniform canopy, improved nutrient use efficiency and, ultimately, higher yields.