Increasing the resource use efficiency of organic soilless production by using natural nitrogen from plasma activated water

Organic production is growing globally following a rising demand. Other than EU-regulations, the USDA regulations (North America), allow soilless cultivation as organic when specific requirements are accomplished, for instance the use of fertilisers from organic source. However, the small volume of growing medium in soilless cultivation can be a limitation. At first, because a certain microbiological activity should be established in the root environment to enable mineralisation of the organic fertilisers. Secondly, the buffer capacity of the system is limited. As a result, the release of plant available N is often lower compared to the crop demand, and it limits the growth. In addition, this has a negative effect on the efficiency of the system, for instance in terms of water or energy use. NO3 is the preferred form for available N. Recently, the use of natural NO3 has been discussed as a possibility to feed the plants in organic soilless productions with readily available N. Natural NO3 is formed in nature during thunderstorms when the lightings fix the N of the air into the water. The natural process of lightning have been mimicked in an industrial process and there is a technology that reproduce the same process and fix N into water in the form of HNO3. The resulting N enriched water is called plasma activated water (PAW). This paper describes the results of a comparison study between a standard soilless organic cultivation with one that used PAW as a source of NO3. We investigated and pointed out the benefits in terms of water, fertilisers and energy use. The results showed a rising water, fertilisers and energy use efficiency with PAW, mainly due to the higher production and a longer period of using a closed-loop irrigation system. In addition to these results, the technical equipment needed to implement this technology into a current organic soilless system is also discussed.