Heavy machinery is compacting agricultural soils. Can we persuade plants to put up with it?

A new study has uncovered the real reason plants have difficulty growing through compacted soil — it's not because they physically can't, it's because of a build up of a common plant hormone.

One of the biggest problems that modern agriculture has created is soil compaction, which is what happens when soil is compressed, turning it from loose and porous to near rock-hard. The cause is primarily heavy agricultural machinery that has literally squished the life out of soils across the developed world in the past several decades.

According to a 2015 UN report, 4 per cent of the global land area is estimated to be compacted to the point where crops can't grow properly. That same report says that soil compaction can reduce crop yields by up to 60 per cent, the assumption being that this happened because plants couldn't break through the tough soil.

New research, recently published in the journal Science, shows that plants stop growing because of the plant hormone ethylene.

The hormone is emitted by plants as a ripening agent, as a defence signal to other plants and as a way for the plant to sense its surroundings.

In properly aerated soil, the ethylene can diffuse away from the roots, but in compacted soil, it builds up and signals to the plant to stop growing.

The researchers found that by genetically modifying the plant to stop sensing ethylene at the root tip, they can maintain the benefits of ethylene, but convince the plant to persevere and punch through tough soils.

You can hear co-author Malcolm Bennett's interview with Bob McDonald at the link above.

Written and produced by Amanda Buckiewicz.