We have prepared these plastic strips (soil biodiversity probes) by loading the holes in them with a special mixture which is similar to the ingredients of a dead leaf. The rate at which this paste is eaten by the soil’s tiny worms, insects, bacteria and fungi tells us how active and valuable these soil inhabitants can be in turning dead plant material into minerals (natural fertilisers), that garden plants need.

Installing the probes

Use a flat-bladed BBQ skewer or a knife to make five holes in your garden soil and put one probe in each hole, with 4cm of the painted section above the soil. Gently use your fingers to compress the soil around the probe as best you can. These probes are most useful when we compare soils of different areas of the garden. Ideally, put two probes in the site with the richest soil, such as under some fruit trees, and the other two in the heavily cultivated area of your vegetable garden. The fifth probe should be used as an indicator by inserting it near the other probes in the ‘best’ site, i.e. the selected undisturbed site. Mark part of the coloured tip of the indicator probe with a small piece of tape to differentiate it from the test probes. Gently pull out the indicator probe every 3 weeks to measure rate of bait disappearance. When approximately half of the holes in that indicator have at least partially disappeared, it is time to remove all four test probes.