Both professional farmers as growers of agricultural or ornamental plants as well as hobby gardeners in their home or allotment garden strive for healthy plants with high yields, which is why fertilizers and artificial irrigation are used. However, fertilizers are usually not applied in accordance with real needs leading to over-fertilization. Over-fertilization has a strong environmental impact by provoking numerous serious environmental hazards. Moreover, mineral-fertilizer manufacturing is highly energy intensive, resulting in greenhouse gas emissions and extensive resource use. Nitrogen has a particularly devastating effect on soil fertility, soil biodiversity and waterbody quality. Air quality is negatively affected by the ammonia emissions resulting from manure use, as well as by nitrous oxide emissions from ground on which manure has been spread. These emissions also increase climate change. The solution of the problem is a switch to precision farming enabling application of fertilizers according to the real needs of plants in optimum doses. To do this, determination of the current supply status of the plants with nutrients is necessary in order to adjust the ideal amount of fertilizer. Hence, there is an urgent need for a new, quick and easy to carry out early diagnosis tool for determination of supply status of plants.