A system for creating a nitrate combined with a liquid. A corona discharge cell to generate an electrical field. The corona discharge cell further comprising a conduit to pass air through the electrical field to produce nitric oxide NO, wherein the air comprises a mixture of at least nitrogen N.sub.2 and oxygen O.sub.2, the conduit for combining the nitric oxide NO with the oxygen O.sub.2 to form nitrogen dioxide NO.sub.2. The corona discharge cell further comprising an injector for combining the nitrogen dioxide NO.sub.2 with the liquid to generate nitric acid HNO.sub.3 which combines with the liquid to generate the nitrate comprised of nitrate radical NO.sub.3 mixed with the liquid.

A corona treatment apparatus comprising a conveyor (10) for moving substrate sheets to be treated along a transport path (12), a plurality of corona electrodes (24) arranged along the transport path (12) on a first side of this transport path, at least one ground electrode (26) arranged opposite to the corona electrodes (24) on an opposite second side of the transport path, and a voltage-controlled power supply circuit (30) to which the corona electrodes (24) are connected in parallel characterized in that a control circuit (38) is provided for limiting a discharge current flowing through each individual corona electrode (24).