Branston trials aim to cut fertiliser emissions

Branston is considering new ways of optimising crop nutrition in the latest phase of its net-zero project aimed at reducing carbon emissions in potato production, from growing through to storage and transport.

Now in its second year of three, the initiative sees Branston partner with agritech firm B-hive Innovations, the University of Lincoln, and crop storage technologists Crop Systems Ltd, as well as multiple growers, to establish a process that will achieve the lowest possible greenhouse gas emissions, while still producing a commercially viable crop.

Branston’s field technical manager Andrew Blair shares his insights on the project here.

In this year’s field trials – which are being undertaken with David Armstrong Farms in Lincolnshire and Arbikie Farming in Scotland – Branston’s main focus is on optimising crop nutrition.

Nitrogen fertiliser is an important part of potato production, but it also makes up a significant proportion of the carbon footprint.

As with most other conventional field crops, potatoes require a considerable amount of fertiliser to encourage plant growth and boost production. But Branston is exploring different ways of reducing growers’ reliance on synthetic fertilisers – for example, by testing novel sources of fertiliser, exploring the potential to reduce fertiliser inputs, and recycling nutrition in the field.

In both the Lincolnshire and Scottish trial fields, the supplier has established a base-line plot with no nitrogen applied. It has also set up further plots with varying levels of nitrogen application, both from conventional and novel sources.

“We’re already noticing differences in the colour and vigour of the canopies, and it will be interesting to see what variation we get in yield at harvest,” Branston said.

Testing plant feeding levels

Branston is also assessing how much fertiliser it can feed through the leaves of a potato plant as the crop is growing. R-Leaf is a new technology which the supplier believes has the potential to change the way we think about crop nutrition.

Developed by R&D organisation Crop Intellect, the photosynthetic catalyst is sprayed onto the leaf and in the presence of sunlight turns atmospheric NOx gases such as nitrous oxide, nitric oxide, and nitrogen dioxide into nitrate that can be used by the plant.

R-leaf could enable growers to reduce the fertiliser application at planting, knowing that they can top up through the growing season.

To work out what the plants need as they grow, Branston is also evaluating a new system from Piketa, which allows growers to analyse crop tissue and measure crop nutrients via the leaves in real time.

“This has the potential to save the cost of lab analysis and allow growers to respond immediately by feeding the crop what it needs, when it needs it,” Branston said.

“The carbon footprint of producing synthetic nitrogen fertiliser is already well documented. What we’re particularly interested in for the net-zero project is what happens as the crop grows and the fertiliser breaks down in the soil.

“In this project we’re working closely with the University of Lincoln looking at soil health and gaseous emissions at field scale throughout the growing season.”

Nitrous oxide – which is 265 times more potent a greenhouse gas than carbon dioxide, according to one study – is released from the soil as synthetic nitrogen-based fertiliser is broken down.

The University of Lincoln is measuring this major greenhouse gas throughout the growing season across all its fertiliser plots.

The university is also collecting and analysing the carbon dioxide and other gases that are released from the soil in the fertiliser trial and the range of different types of cultivation being assessed in the net-zero field trial.

A commercially viable crop

Varietal development may also play an important role in reducing the carbon footprint of potato production. New varieties from plant breeders are being assessed to see which ones can perform with low levels of nitrogen and produce a high-quality, high-yielding crop with reduced irrigation and lower-quality land.

“While much of the work that is being undertaken is around reducing inputs, the team is well aware that yield and quality are still very important,” Branston said.

“Any reductions that lower the marketable yield could necessitate an increase in other inputs and be detrimental to the overall carbon footprint. We’re looking at ways to get the balance right for truly sustainable potato production.

“In reality, a step change is required from the potato industry as it looks to achieve ambitious net-zero targets. A ‘business as usual’ approach isn’t going to cut it anymore, and the responsibility rests across everyone involved to find solutions.

“The direction of travel is changing, and for the most part the industry seems to be steering in the right direction. However, a consistent, concerted, combined effort is needed to sift the ideas and find data-backed, sustainable solutions that can help us achieve our collective target.”