The kit is used for habitat surveys, says Mike Parfitt, field teacher at the Pulborough reserve.
"Before we had it, we would have had to take soil samples back to the education centre to have them weighed and measured before we could do the tests. Now all pupils need to do is push the probes into the earth and take a reading."
Pulborough Brooks is an area of grassy wetlands, which dried up when flood banks were created along the River Arun in the Sixties, and which is now being returned to its former state.
The main objective is to attract the birds which were gradually deserting the area. Since the RSPB took it over, the number of shoveller ducks, for example, has risen from 22 to 260 and the number of mute swans from 88 to 124.
The reserve has a variety of habitats, including woodland, higher grasslands scrub and open water, and a vigorous education policy promoted by five part-time field teachers. Last year about 4,500 children passed through, around one school a day in term-time.
Last month one of these parties, a group of 11 to 12-year-olds from the independent Brighton College Junior School, helped to pilot the Enviro-Probe programme. An important part of their biology curriculum, the day was intended to provide material for a project on the woodland environment.
Penny Schuler, a field teacher, explained how they would use a transect line for their investigation of the woodland habitat at ground level. Points along the line would be marked to delineate the half metre square areas being sampled.
Having set up their line, groups of pupils took measurements, pushing the probes into the soil, or holding up the light meter and noting the results. They also noted the composition of the soil and the vegetation in each small area.
The figures began to mean something during a feedback session. Vegetation changes were linked to changes in soil, light, moisture and the other indicators the children had investigated.
At the top of the slope where it was very dry there was a lot of leaf litter and not much vegetation, half way down a lot of bracken and moss - which can grow together in fairly dry soil - appeared. At the bottom a dry, sandy, well-used path ran through the valley.
An enthusiastic mini-beast hunt uncovered centipedes, millipedes, wood lice, beetles and shield bugs at the top of the slope. A discussion followed about how the animals survived in such a dry, dark, fairly vegetation-free habitat.
In the afternoon, during a walk through the reserve, Penny Schuler emphasised that it was a "man-managed" environment - not nature doing its own thing. Examples of human intervention included recently-grown willow hedges, grazing grounds and a badger flap (the equivalent of a cat flap, which allows the animals to leave and enter areas from which rabbits are barred).
At a pond they searched for water creatures using an illustrated key to identify them. Later they were able to draw a food pyramid with the dragon fly and damsel fly at the top, and the numerous plant eaters at the bottom.
Woodland is only one of the habitats open to investigation by Enviro-Probe. Schools can also explore ponds using the same monitoring equipment plus dip sticks to test for phosphates and other pollutants, or compare different types of animal life in contrasting environments such as still ponds and flowing streams, or sunlit and shaded ponds. It makes for a stretching and tiring day, but one filled with variety and a great deal of hands-on experience.
* RSPB Pulborough Brooks Nature Reserve, Wiggonholt, Pulborough, West Sussex RH20 2EL. Tel: 01798 875851. A teacher's guide, with curriculum links, background information and an explanation of the equipment is supplied to schools taking part in any of the Enviro-Probe projects. Further information about other sites where the project will be available from The RSPB, The Lodge, Sandy, Bedfordshire SG19 2DL. Tel: 01767 680551.