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In the first study of its kind, research undertaken at the University of Southampton shows that biochar in soil has acts as a powerful tonic to stimulate plant growth.

The findings are published in the journal
Global Change Biology Bioenergy.

The scientists, led by Professor Gail Taylor, found that when thale cress and lettuce plants were subjected to increasing amounts of biochar mixed with soil, up to 50 tonnes per hectare per year, plant growth more than doubled.

Plant growth hormones activated

They also tracked for the first time the changes in genetic expression that followed from applying biochar.

The response of more than 10,000 genes was followed simultaneously, and two growth promoting plant hormones – brassinosteroids and auxins, together with their signalling molecules – were stimulated by the biochar.

Professor Taylor said:
“Our findings provide the very first insight into how biochar stimulates plant growth – we now know that cell expansion is stimulated in roots and leaves alike and this appears to be the consequence of a complex signalling network that is focussed around two plant growth hormones.

A huge potential for biochar – to store carbon, and fertilize

Many previous reports have shown that biochar can also stimulate crop growth and yield, providing a valuable co-benefit when the soil is treated with biochar, but the mechanism enabling this to happen was unknown – until now.

Biochar is produced when wood is combusted at high temperatures to make bio-oil and has been proposed as a method of geoengineering. When buried in the soil, this carbon rich substance could lock-up carbon and reduce greenhouse gas emissions, while also acting as a potent fertilizer.