Category: Gardening

Nitrogen makes up 78% of the air you’re breathing right now. Plants can’t touch it. That single inconvenience is why the world spends fortunes on fertiliser.

Synthetic nitrogen fertiliser is one of the reasons eight billion people can eat. It’s also enormously energy-intensive to produce, expensive for farmers, and a significant source of greenhouse gas emissions and water pollution when it runs off fields.

But there’s a workaround, and it’s been sitting in the soil the whole time.

Certain bacteria — rhizobia — form nodules on the roots of legumes and convert atmospheric nitrogen into a form plants can actually absorb, in exchange for energy from the plant. It’s called biological nitrogen fixation.

The question was whether you could make it work reliably, at industrial scale, in tropical soils.

When Mariangela Hungria started, almost nobody thought you could.

She’s a microbiologist from São Paulo who studied under Dr Johanna Döbereiner, an early champion of using microorganisms in tropical agriculture. In 1991 Hungria moved to Londrina, in Paraná state, to start a soil microbiology laboratory at Embrapa’s National Soybean Center.

There was essentially no existing research on biological nitrogen fixation for soybeans in the tropics. She built the programme from scratch.

The work was painstaking. Selecting elite strains of rhizobia. Testing what happened when you introduced them to plants. Establishing how environmental stress affected performance. Identifying plant genotypes that partnered well with the bacteria. Then convincing farmers to re-inoculate their seed every single year — which she demonstrated could increase yields by up to eight percent compared with relying on synthetic fertiliser alone.

She also became the first to isolate strains of Azospirillum brasilense suitable for use with non-legume crops, which opened the same approach up to maize, wheat, rice and pasture grasses.

Over a forty-year career she and her group developed more than thirty microbial technologies.

The results are on a scale that’s difficult to hold in your head.

Her products have been used across more than 40 million hectares in Brazil. The World Food Prize Foundation estimates they save Brazilian farmers around $25 billion a year in input costs and prevent the release of 230 million metric tons of CO2-equivalent emissions annually.

And over the same four decades, Brazilian soybean production rose from 15 million tonnes in 1979 to an anticipated 173 million tonnes. Brazil became the world’s leading soybean producer and the global leader in the commercial use of biological inoculants.

In May 2025 she was named the World Food Prize Laureate, receiving the $500,000 award. Gebisa Ejeta, who chairs the selection committee, cited extraordinary scientific achievements in biological nitrogen fixation that transformed the sustainability of agriculture in South America.

Her own reaction was less formal: “I can’t quite believe I am now receiving the World Food Prize.”

This year she was named to the TIME100.

She has also supervised more than a hundred masters and doctoral students — which, given where she started, may end up mattering as much as the bacteria did. Döbereiner taught Hungria. Hungria taught a hundred more.

There’s a version of the future where feeding people means more chemistry, more energy, more inputs. Her entire career is an argument for a different one: that a great deal of what we’re paying for is already happening, for free, underneath us — and the job is to understand it well enough to get out of its way.

Forty years on one invisible thing.

What’s actually possible is suppressed from public view. This is a diagram of an actual compressed-air power plant that ran for over 70 years; it was shut down because an insurance company claimed that it attracted too many observers and someone could get injured, so they shut it down… They are trying to control the rain, the groundwater, your ability to save seed, and so much more – why wouldn’t they hide basic things like nearly-free energy generation? This is #Permaculture in practice, and this is a diagram from The Permaculture Student 2: https://www.thepermaculturestudent.com/shop/the-permaculture-student-2-the-textbook-ebook

A pasture grazed by cattle alone is a good pasture. Put cattle and sheep on it together and it becomes something else.

The cattle take the long grass, the coarse stems, the rough patches. The sheep come behind and clear what the cattle left: the short regrowth, the wildflowers, the plants a cow won’t touch. Two heights, two mouths, two patterns. Twice the use, none of the waste.

Add a goat and the bramble line retreats. Add a pig on the woodland edge and the parasite cycles break. Add a few geese and weeds you never knew you had quietly vanish. Each animal eats what the others refuse and breaks the worms the others carry. The system tunes itself.

The result is about as biodiverse, productive and low-input as farming gets. More carbon in the soil. More birds. More wildflowers. Less disease. Less spent on feed, wormer and fertiliser. Ground that would grow no crop at all turns into meat, milk and wool.

This is the oldest idea in farming. Nearly every working agricultural culture has done it since the beginning: Roman estates, medieval manors, Mongolian camps, Welsh hill farms.

The single-species, single-field, single-product model that shoved it aside is barely a century old, and it is running out of road on every measure you can name.

The fix is older than the problem. A Welsh farm with cattle on the low pasture, sheep on the high, a goat on the bramble line and a couple of geese in the orchard.

The farmer would explain the whole thing in four minutes, if anyone asked.

The policy paper never has.