A handful of start-up companies are looking at how they can harness soil microbes to make nitrogen for crops instead of using industrial processes. It’s one of the leading-edge technologies that threaten to upend how agriculture is practised.

One of the higher profile companies is Pivot Bio, started 11 years ago by former University of California researchers who mapped the genome of microbes that can take nitrogen from the air and fix it where it is available to the roots of cereals and oilseeds.