A compact technology which uses a laser to generate a ‘plasma plume’ from soil samples could offer a solution to the challenge of measuring soil carbon on agricultural land.
A team based at Tampere University in Finland developed the mobile device based on the principles of laser-induced breakdown spectroscopy, or LIBS, with the aim of both measuring both total soil carbon content and where the carbon is distributed within the soil, through generating a 3D spatial model.
To test the technology, they tested samples from 28 randomly-selected locations and at different depths, in a field cultivated with a red clover and grass mixture. They then validated the results from this approach by cross-referencing them against data from testing a further 167 samples using a more standard approach, the dry combustion method.
Ready for carbon monitoring schemes?
They found that the device performed at a degree of uncertainty of around 10% — a level that the researchers say would make it worthy of consideration for incorporation as part of ‘carbon farming’ initiatives.
Current laboratory-based approaches for measuring soil carbon are time- and labour-intensive, they wrote in the journal Geoderma. In contrast, they reported a measurement time of one minute per sample for their own, in-field system.
“In addition, LIBS analysis can be performed on-site reducing the need of soil storage capacity and, as the calibration for a field block can be obtained from a small number of samples, the sample handling in laboratory is reduced substantially,” they said.
The approach can also be used to identify soil type, and identify micro-variations in soil composition, they added.
