Scientists from The University of Western Australia have outlined how farmers can create a ‘positive feedback loop’ on their land that enhances overall soil carbon (C) sequestration, improves crop productivity, and mitigates climate change.

In a recent Soil and Tillage Research opinion article, the collaborative research team determined that improved management of cultivated land could significantly contribute to CO₂ mitigation, soil fertility enhancement and agricultural productivity.

Through the process of photosynthesis, vascular plants capture atmospheric CO₂ for C assimilation – storing C in the ‘plant biomass’ (above and below-ground parts of the plant).

Plant roots are the primary route of C entry into soil organic carbon (SOC) pool.

SOC is critical to global C cycling, with the upper soil layers (30cm to 100cm) estimated to contain about three times more C than the entire atmosphere.

Image: Schematic diagram illustrating the various components for enhancing crop productivity to recarbonise soil.

Farmers can accelerate atmospheric C sequestration into the SOC pool through best agricultural practices, such as reduced soil disturbance, permanent soil cover, rotation with legume crops, improved water and nutrient management, integrated nutrient management, and efficient insect pest, diseases and weed control.

The researchers concluded that these positive agricultural practices could then sequester between 80 and 130 gigatonnes of C as SOC, which would create a positive feedback loop for overall C storage.

Given that global C cycling plays a vital role in mitigating climate change, lead author and Director of The UWA Institute of Agriculture, Hackett Professor Kadambot Siddique, said SOC had deservedly gained significant global attention in recent years.

“World leaders have been advocating for changes in farming practices in order to promote atmospheric carbon sequestration into the soil, and therefore reducing carbon emissions,” Professor Siddique said.

Our opinion article delves into the nexus between photosynthesis and soil C sequestration, highlighting its significance in enhancing farm productivity while mitigating climate change.”

Given the key role of photosynthesis and biomass production on soil C sequestration and storage and their consequent impact on climate change, the researchers concluded that future research and development was needed.

This included exploring site-specific sustainable farming practices, such as conservation tillage and cover cropping, developing crop and pasture genotypes with dual benefits of increased yield and C sequestration, developing techniques for incorporating crop residues into the soil, promoting carbon-based amendments, developing soil management practices, and encouraging the cultivation of crop and pasture species that were efficient in fixing carbon.