Reducing reliance on synthetic nitrogen is at the top of most grower’s agendas given the current supply and pricing challenges, as well as environmental concerns over its use.

With a global nitrogen market worth about $193bn (£178bn) in 2022, the opportunity is huge for those who can provide successful alternatives and has already led to a huge amount of investment in research and development of new solutions.

See also: How a grower is aiming for a 10% yield raise using a data tool

At the recent World AgriTech Innovation Summit in London, a number of promising technologies were discussed.

Biological solutions

One of the biggest investment areas has been in biological or microbial products with the potential to provide nitrogen directly for plants.

Gene edited

US-based Pivot Bio’s technology uses gene editing to programme the DNA of bacteria to convert atmospheric nitrogen into plant-available ammonia in the soil.

The bacteria, which are naturally occurring in the soil, can fix nitrogen but it shuts down when the microbe identifies there is enough ammonia in the immediate surrounding area.

Pivot Bio has “flipped the switch” so the microbe still fixes nitrogen even when high levels of nitrogen surround them.

“There are many bacteria that can take nitrogen out of the air to make ammonia and feed themselves, and make proteins and grow,” explains Ernie Sanders, Pivot Bio vice-president of product development.

“We isolated those microbes and reprogrammed them to make more ammonia than they need themselves and excrete it out.

“Our product grows on the outside surface of the plant roots and the ammonia is immediately taken up by the plant.”

The firm has developed a couple of products – Pivot Bio Proven 40 for maize and Pivot Bio Return for wheat and barley.

Both are designed to be applied on the seed, with the microbes providing the opportunity to replace 40kg N/ha in maize and 25kg N/ha in cereals, says Mr Sanders.

“As soon as the seed germinates and sends out roots, our bacteria colonise the roots and grow, using the exudates that come from the plant as a food source.

“Our product delivers the most nitrogen when the maize or cereal plant needs it the most.”

The products were used across 1.2m hectares in 2022 at a cost of £47/ha ($21/acre), with the vast majority of growers using it to replace synthetic nitrogen application rather than as an additional source of N, Mr Sanders says.    

Future developments will continue to aim to increase the amount of synthetic nitrogen that can be replaced.

Non-gene edited

No testing has so far taken place in the UK, but trials are ongoing with different strains – developed without gene editing because of the more restrictive regulatory environment – in Poland, Germany and France, he adds.

What makes UK-based Azotic Technologies nitrogen-fixing bacterial product different is that it multiplies and grows within the cells of the plant.

Gluconocetobacter diazotrophicus bacteria were originally found in sugar cane. They have been sold as Envita in the US since 2019, with millions of acres treated in 2021, says Nolan Berg, the firm’s head of global marketing.

That footprint is set to expand with the product also now available in the UK and Europe, under the brand name Encera.

The technology is non-gene edited or modified and is crop-agnostic, with the focus on crops such as maize, potatoes, rice, wheat and barley.  It’s usually applied as a post-emergence foliar spray, although it can be used as an in-furrow application or seed treatment, says Mr Berg.

“Once the bacteria gets into the plant, it will grow as the plant grows.

“By physically getting into the plant cell where photosynthesis is taking place, it creates a natural source of nitrogen filling the gap between what the crop needs and what the crop can get from the soil and roots.”

In North America, many growers have used it as an additive to usual nutrition programmes with about 5-10% increase in yield in crops from a treatment costing about $15/acre (£37.50/ha).

Alternatively, it can be used to replace about 25% of the synthetic nitrogen fertiliser requirements in maize – about 55kg N/ha – or up to 50% in rice, without any drop off in yields, Mr Berg says.

“We’ve also seen consistent 5-10% yield increases in wheat and barley in trials when used with a full nutrition programme.

“We’re still working on quantifying how much N it can replace in these crops, but early results suggest potential for reductions of 10% or more.”

The firm is planning an introductory demonstration programme where product is provided to farmers free of charge to establish the product’s efficacy across Europe, including the UK, Mr Berg adds.

Digital tools

Digital tools, in conjunction with more efficient forms of nitrogen fertiliser, have shown the potential to reduce applied N requirements in BASF’s Better Barley project.

The project was run on a 50ha field of malting barley on a German farm. It compared the use of variable rate applications of urea fertiliser treated with nitrification inhibitors driven by data insights from BASF’s digital platform, Xarvio, with flat-rate applications of uninhibited fertiliser.

The aim was to maintain or improve yield and malting quality while minimising fertiliser inputs and carbon dioxide equivalent emissions, explains Matthias Nachtmann, BASF European business development manager.

Nitrification inhibitors added to fertilisers protect N against losses due to nitrate leaching and nitrous oxide emissions. As a result, more N is available for the plants.

“We give the plant support in the race for nitrogen uptake of the plant so, depending on the weather, the plant can take up nitrogen over a longer period,” explains Mr Nachtmann.

“That gives a higher nitrogen use efficiency and lower emissions.” Using variable rate applications further improves efficiency, he adds.

In this trial, Xarvio field manager analysis of the previous 15 years of plant biomass development, overlaid with yield maps, provided the basis to create Xarvio powerzone maps to identify areas of higher and lower field performance.

These were used as the basis for the variable rate applications.

Results from the trial are still being analysed, but the preliminary outcome suggests target grain nitrogen levels were achieved while saving about 20-30kg N/ha and improving yields by about 1-2%.

“We’re keen to run the Better Barley project on more soil types, including in the UK,” Mr Nachtmann says.

Yara’s digital tool AtFarm, which was launched in 2018, also uses satellite data to create variable rate application maps based on the N-Sensor algorithm.

“We’ve been able to improve yields by 6% by using this tool and also reduce nitrogen fertiliser use by 12%,” says Monica Andres Enriquez, Yara’s executive vice-president in Europe.

To encourage farmers to use this type of precision farming tool, Yara made the AtFarm free this year. The company has also been lobbying for further support to improve access to digital tools for European farmers, she says.

Breeding

Gene-editing company Inari is aiming to reduce the amount of N needed to grow maize by 40% through its SEEDesign technology platform.

It is also targeting a 40% reduction in water requirements for the crop, while increasing yields by 10%.

Reducing N requirements by 40% is an audacious goal, admits Inari chief executive officer Ponsi Trivisvavet.

“Crops’ nitrogen use efficiency is determined by a system of genes and gene networks that are incredibly complex.

“There is not a trait that can be added or a single gene that can be knocked out to deliver the systematic changes in plants needed to improve nitrogen uptake, which is why it has historically not been addressed.”

But recent advances in artificial intelligence, genomic sequencing and gene editing have unlocked new tools and knowledge, she says.

Inari pairs predictive design with advanced multiplex gene editing.

“Predictive design works to create a deeper understanding of the unique pathways and genomic interactions within the plant.

“These insights can deliver editing ‘blueprints’ to guide our breeders and scientists in making a range of gene edits with the plant’s own DNA.”

Making multiple edits to the plant at the same time is necessary to address the natural complexity of plant gene networks, such as resource use efficiency, she says.

But gene editing is still in its infancy. It’s just 10 years since the discovery of a ground-breaking technology – clustered regularly interspaced short palindromic repeats (CRISPR) – was published.

Initial products such as browning-resistant mushrooms and tomatoes containing higher amounts of gamma-aminiobutyric acid, which can help support lower blood pressure, are the result of single-gene edits.

“Given the complexity and depth of knowledge necessary to address gene networks, the first multiplex gene-edited products have not yet hit the market,” Ms Trivisvavet says.

“But given the speed at which technology is advancing, we expect that to change in the next couple of years.”

However, accessibility to this technology will depend on regulatory approvals, she stresses.

“It is crucial to have a clear regulatory path accessible to companies and organisations of all sizes, to allow multiplex gene-edited products to get to market at a speed that keeps pace with both our growing global population and our fast-changing climate.”