Measuring soil carbon

As interest intensifies in soil carbon sequestration for climate change mitigation there are many attempts to establish reliable ways of measuring soil carbon. There is also doubts around our capability to accurately measure carbon.

… applying stringent MRV* schemes to soil organic carbon has proven difficult, due to the large measurement error. The error is in general higher than the actual change one would like to detect over time in SOC stocks in soils. The error is due to the high spatial variability of soil properties, large errors in the sampling process and large errors in the actual measurements in the laboratories. (Luca Montanarella, Senior Expert, Land Resources Unit, European Commission).

Ideally globally agreed protocols that are inexpensive can be made available to land managers to prove sequestration.

Landcare Research; Manaaki Whenua summarises advances in soil carbon measuring in Reducing New Zealand’s Agricultural Greenhouse Gases: Mapping Soil Organic Carbon Stocks.

Examples of SOC measures (under construction)

Quick carbon

Quick carbon, based at Yale, “have recently developed a soil carbon measurement protocol that makes use of low-cost field reflectometers. These affordable, pocket-sized devices measure soil carbon using the reflectance of soils in the visible and infrared spectra. As carbon content increases, a soil’s color darkens, giving it a slightly different spectral signature than soil with lower carbon content. Standard benchtop spectrophotometers used in similar work cost $3,000-$10,000 and are not portable, whereas this device can be produced for an order of magnitude cheaper”.

  • Measurement, reporting and verification (MRV)