How do we solve the nitrogen issue?

How can everyone in the agricultural industry – manufacturers, distributors, retailers and of course growers – act more innovatively in their use of synthetic nitrogen, addressing its contributions towards greenhouse gas emissions (GHGs) while maintaining global crop yields?

British company Azotic Technologies has found a responsible way to manage this issue using a discovery in South American sugarcane some 30 years ago to develop a viable solution to the nitrogen dilemma. It was back in 1988 that two researchers identified the bacterium Gluconacetobacter diazotrophicus living within Brazilian sugarcane, firing the starting gun on a fascinating chain of research.

″It’s been the Holy Grail of plant scientists for years: how to replicate the easy nitrogen-fixing abilities of legumes?″ says Tom Tregunno, Global Market Manager at Azotic Technologies, based in York, England.

″We’ve long known about their ability to take atmospheric nitrogen and make crop-available nitrogen. The world’s soybean crops absolutely rely on this phenomenon; soybeans would not be a global success without the Bradyrhizobium that colonises the plant’s roots, forming the precious nitrogen-capturing root nodules.″

Bradyrhizobium is a picky partner, however. It won’t colonise the roots of other species, such as rice, maize and wheat that are the world’s most important crops. Nor will the Rhizobium commonly applied to other legumes such as fava beans and peas. Scientists’ solution has been to try to genetically modify cereal crops – effectively ‘tricking’ the various rhizobacteria species into colonising their roots and stimulating nodule production.

″The trouble is, while it sounds relatively simple given the rapid advances in gene editing in recent years, it’s more complicated than that,″ Tregunno points out. 

″We’re still way off from a practical, mass-market solution, and even then it would require extensive regulatory approvals. In some parts of the world, especially Europe, that approach would be a dead-end – there’s no regulatory route for GMO crops.″

This is where Gluconacetobacter diazotrophicus plays its trump card. Gd enables any crop to fix atmospheric nitrogen, allowing farmers to reduce their reliance on fertiliser.

″It really does sound too good to be true,″ Tregunno acknowledges, ″but the research that led us here, conducted initially at the University of Nottingham, augmented by the results from Azotic’s state of the art Labs in the UK, and then coupled with early field trials, created a buzz within Azotic.  From there, Azotic and its customers have created field-scale evidence from four years of commercial application in North America, the world’s largest corn-producing region, resulting in Azotic’s go-to-market message: Gd can reduce synthetic nitrogen applications without compromising crop yields or it can allow growers to push for more yield with the same fertiliser.

″It’s a bold claim, but it’s backed by science. Now we’re proving it not just in trials, but commercially.″

Corn samples taken from Nebraska, USA, under the same fertility program

Understanding the science

Gd is an endophyte, a bacterium or fungus that lives only within a plant. Ubiquitous in plant biology, with hundreds of thousands of examples identified, the relationship is – like Bradyrhizobium and the soybean – symbiotic. Benefits to the plant are diverse. Researchers have found species that promote plant growth through synthesising plant hormones such as auxin and gibberellin, while others help counter stress conditions, improve uptake of micronutrients and even ward off competing plant species through chemical inhibition.

Such characteristics have prompted agricultural researchers to look at them with renewed interest in recent years; several endophyte-based biologicals are already in use. It’s Gd’s ability as a diazotroph – a nitrogen-fixing bacteria – that distinguishes it from other endophyte inputs.

Oats leaf cells colonised by Gd

″Gd takes nitrogen from the atmosphere and supplies it directly to the plant, without root nodules, without genetic modification,″ Tregunno enthuses. 

″You hear the term ‘game-changer’ applied to anything these days, but helping agriculture to solve its climate change problems isn’t a game. Gd is actually an ‘industry-changer’, because of its potential to effect a dramatic shift in how farmers use nitrogen.

″This is a technology that can be used on any crop. It is not crop-specific. That’s the significance.″

When Gd is applied to a crop, either in-furrow at planting or later as a foliar spray, it uses enzymes to enter cells and spread throughout the plant, reproducing as the plant grows, and forming in-cell vesicles.

″That’s Gd’s equivalent of the root nodule, but it’s not limited to the root,″ Tregunno explains. ″Inside the vesicle, Gd captures atmospheric nitrogen to produce ammonia, NH3, just as rhizobacteria do.

″Gd’s difference is that it gives each cell in the plant its own mini nitrogen-fixing unit,″ Tregunno continues. ″It delivers nitrogen to the location in the plant where photosynthesis takes place. This is where the crop’s growth and yield are effectively determined.″

Systemic nitrogen fixation

Azotic – the company’s name inspired by azote, the name given to nitrogen by the French chemist Lavoisier – launched Gd under the trade name Envita in 2018.

By this time, the company was clear about the abilities of Gd to displace synthetic nitrogen. ″Trials were showing that maize crops treated with Envita could reduce the need for synthetic nitrogen by around one-quarter. 

″What’s more, when used as part of a conventional fertiliser programme (not reducing nitrogen), grain yield increased by around 0.5t/ha,″ he reveals. ″That’s more than enough to cover the cost of treatment and provide a strong return.″

But it’s not just about the nitrogen saved, Tregunno stresses. ″We’re facing the very real risk that climate change will disrupt crop production in the years ahead″.

″Weather and rainfall patterns are already changing. Sometimes we see extended dry spells during early establishment, sometimes precipitation events are heavier and longer.

″Crops need moisture to draw on soil nitrogen reserves through their roots, which means that in times of water stress nitrogen uptake can be limited. But Gd-treated crops appear to have access to nitrogen even when soil moisture levels are low,″ notes Tregunno. 

″US and Canadian users have commented widely on how Gd helps crops better manage heat and drought stress. Equally, when there’s heavy precipitation early in the season – which can wash applied nitrogen from the soil – Gd can ‘fill the gap’ and maintain crop yields.″

Nitrogen when and where it is needed

Scaling up

″Biologicals, biostimulants, biomolecules – whatever we’re talking about, these are unfamiliar classes of product. Most farmers are well-versed in the use and application of agrochemicals and other conventional crop inputs – indeed, many will practise their own agronomy too – but there’s an element of uncertainty with anything ‘bio’ and especially when we’re promising something that affects their use of something as fundamental as nitrogen fertiliser.″

It's why Azotic has not only focused on how Envita – known as Encera in Europe, and launched in the UK and 4 other EU countries in 2022 – interacts with agrochemicals in tank-mix, but also pursued an extensive trials and demonstration strategy which takes the product beyond the usual confines of small plots and out onto field-scale crops.

″You only get one chance to make a first impression,″ Tregunno notes. ″Many ag biologicals have previously overpromised and underdelivered. Sometimes that’s been the fault of the product itself, but it’s also true that some manufacturers have not done enough to understand and communicate that biologicals need a different approach.

″More variables come into play – soil type, the soil’s state of health, previous crops, varietal differences, timings, and so on. We’re not only extending our own trials, but also working to get it out on the farm. We can help them fit it into their farming system, while also conducting an enormous, ‘large area trial’ from which we can draw the clearest understanding yet of how it works across farming systems and the effect of all those variables on its performance.

″Analysis of this data will further refine our understanding of the product and its potential to change our relationship with synthetic nitrogen.

″With a product like this that can work in every crop – we’ve had solid and successful results in corn, wheat, soybeans, rice, potatoes, cotton, alfalfa, and protected crops like tomatoes – we have a rare chance to transform agriculture: improving food security, reducing nitrogen fertilizer pollution from GHGs and nitrate runoff into our waterways, all the while helping to drive higher production and increased profits at the farm gate.″

This article was originally published in the magazine 2023 Biologicals Special.