One product of this kind, the Q-Box NF1LP made by Qubit Systems, operates by measuring the hydrogen (H2) given off in the nitrogen-fixing chemical reaction enabled by nitrogenase enzymes.
Q-Box NF1LP is an experimental package using an open-flow gas exchange system for measurement of nitrogen fixation in H2-producing legume symbioses.
Measurements of nitrogenase activity on up to three plants is possible, i.e. a four-channel system including a reference sample.
The product must be supplied with many potted samples of the plants and of the neighbouring soil, taken from separate areas on the farm or field under study.
[4] To test soil properly, it must be free of added nitrogen fertilizers, which have harmful effects on the Herbaspirillum bacteria needed for fixation.