Biofertilisers have an important role in sustainable agricultural development, as they maintain soil fertility, they improve the resistance of field crops, increase yield safety and quality with no chemical load on the environment.

We examined the efficiency of natural foliar fertilisers between 2006 and 2008 under field conditions on meadow chernozem soil in the southern production area of Hajdúszoboszló. During our examinations, we wanted to know whether the foliar fertilisers Natur Vita (Chlorella vulgaris and Spirulina platensis), Natur Plasma (Chlorella spp.) and Amalgerol Premium (alginate, mannitol, laminarin etc.) provide further yield increase besides basic fertilisation in population treatment and stubble treatment. The efficiency of these products was tested in maize population and the examinations were also extended to potato production in 2008.

The examined products are able to improve the conditions of the potato population and they provide a further yield increase on top of the basic fertilisation depending on the applied treatment, but their combined application does not result in a significantly higher yield than applying the products on their own.

Keywords: potato, SPAD, foliar fertiliser, efficiency