A trench is excavated using shuffles or other machinery until the desired depth of incubation, for example 40 or 60 cm deep. Sideways of the trench small holes are made to fit the resin bags under an undisturbed soil profile. Since variation may be high, at least four replicate resin bags per trench are used. The trench is filled back up with soil and marked.
The resin bags can remain in the soil for a period of several months, possibly up to a year depending on how much nitrate is expected to leach out.
At the end of the incubation period the trench is opened up and the resin bags are carefully removed.
Some resin bags are stored in the fridge as blanks and later on treated as the other bags.
