This indicator measures soil organic matter (SOM) present in soil samples  Microbes use soil organic matter as food, and their activity allows the mineralisation into plant-available soluble forms of nutrients that are ‘locked-up’ in organic matter, or in the soil. SOM is therefore a measure of how healthy a soil ecosystem is.

About half of Jersey's surface area is farmed commercially, and this is where any changes in soil organic matter are likely to happen. That is why arable land is the focus of this indicator. For cultivated arable fields used for potato production, an initial survey of ten fields was undertaken in 2016 and the sample is now 16 fields. The average SOM levels for this land over the three-year period is 3%. Increasing it to between 4-5% in the future would take it from an 'acceptable' level, up to 'good' or 'excellent'.