March: Testing, testing, testing
Published on: 14 March 2025
Testing, testing, testing
It’s fair to say this project excites me, writes Dr Mike Thomas. You don’t get the chance to work on projects of this magnitude – how to find new ways to fix atmospheric nitrogen – very often.
Just to recap: we’re looking to identify microbial strains that can fix atmospheric nitrogen in non-legume crops. Currently the sorghum, maize and millet – staple crops around which smallholders’ livelihoods revolve – rely on artificial nitrogen to achieve anything more than baseline performance and yields.
Synthetic nitrogen is expensive and does little to help soil health. Instead, we want to furnish them with a sustainable, biological solution that can deliver those income-boosting yields, affordably and without environmental implications.
In the last update, we talked about how our University of Nottingham post-doc student, Nikki, was identifying a longlist of candidates for further assessment. Nikki’s been trawling through various cultural libraries – our own, those of our partners, and other commercial sources – and cross-matching with the literature, and at completion we had a group of about 80 candidates that we expected would have a capacity for nitrogen fixation.
The Big Test
Then it was time to whittle down that list. First we checked each one for the presence of the nif gene, the one responsible for producing the vital nitrogenase enzyme that can turn atmospheric nitrogen into ammonia.
From that sift, we took forward a further group in which we tested the effectiveness of that nif gene: was it being expressed? To do this, we set the microbes growing on nitrogen-free media and checked for the presence of ammonia.
That gave us a further reduction in candidates: only those with clear evidence of ammonia excretion were allowed to make the cut.
We’re now down to a shortlist of five or six, pending analysis of the last tests. These candidates will be put through their paces both in a pot trial, and in an open-air field plot trial.
Into Trials
That field trial was just planted this week, which means we’re now well on the way towards quantifying the benefits and abilities of each of the candidate microbes. What is their effect in the field? What N-benefit can we attribute to each of them? How do they influence the crop’s agronomic output?
Metrics under examination include not just yield, but others such as root development and any noticeable effects on germination and emergence.
These early trials are focused on wheat: we have familiarity with the crop, and we need a crop that suits UK conditions, and UK soils. But of course, the end goal is African maize, in African soils, which is why an ongoing part of the project is to develop relationships with African partners, with whom we can get a series of trials underway across the African continent.
We expect to have these underway before the end of the year, initially in Kenya, Tanzania, Egypt, Mali, Ghana, Senegal and Nigeria. Exciting times – watch out for the report in the next newsletter, and keep up to date with progress via our website.