Conservationists may cringe at the environmental impact of lignite, but Solid Energy has found a truly "green" use for at least some of the energy resource.
Humates from selected lignite seams at its New Vale mine in Southland have gained organic certification from BioGro New Zealand, but could also benefit farms using chemical fertilisers.
Solid Energy's environmental business manager Paul Weber said in a statement that humates were rich in humic and fulvic acids which help retain nutrients for plants, and scientific testing has shown lignite from some seams were particularly high in humic acid.
By slowing the leaching of nutrients such as nitrogen, humates ensured more were available to plants.
"By helping soils retain nitrogen, humates could offer financial benefits to farmers and also reduce the negative effects of leaching on aquifers and rivers."
The humate market was relatively new with just 2000 tonnes used on New Zealand farms and gardens each year and virtually all of that was imported from Australia.
Dr Weber expected that market to increase to 10,000 tonnes and he hoped Solid Energy would capture the bulk of the market.
Typically, farmers mixed between 4% and 10% humates with fertiliser or lime, but Dr Weber said research with Lincoln University would include options for liquid humate for use in blended fertilisers, water treatment and even for cleaning up contaminated sites.