In our comparative greenhouse experiment, the effect of three biofertilisers with bacterial and algal composition (Biorex I-II; Nature Terra; Amargerol) were studied on the plant nutrient supply and on the soil N-, P-, K-, Ca- and Mg -supplying capacity. The test plant was maize (Zea mays L.), and we applied meadow clay soil for the experiment. The examined plants were harvested in 6 weeks after the sowing date. In addition to the weight of the examined plants, their N-, P-, K-, Ca- and Mg content were also determined and the N-, P-, K-, Ca- and Mg uptake of the plants was calculated. We determined the readily available nutrient forms from the treated soils. These were the following: total N from 0.01 M CaCl2 soil extract and P-K-Ca- and Mg from AL-extract.

The results of the experiment showed that the bacterial and algal biomass compositions of young maize plant weight was reduced in comparison to those of the control, while nitrogen concentration was significantly increased, but the soil did not supply the appropriate amount of nitrogen.

Due to the high P content of the soil examined in the experiment, the P supply of the young maize was provided, but the three biofertilisers have not increased the P content of plants compared with the control.

In this phenophase, the available K supply of the soil has been sufficient. The treatment increased the plant K concentration compared with the control.

Based on the examination of the Ca concentration in the plants, less contrast was observed in comparison with literature data. The Ca supply of the young maize plants was not sufficiently provided.

According to the Mg concentrations measured in the examined plants, the magnesium supply was not optimal. The treatments have had a positive effect on this parameter. The three biofertilisers increased the Mg content of these plants compared with the control.

Our results show that the performed treatments mostly increased the concentration of nutrients used in the experiment to a lesser extent in relation to the control plants, but they could not provide optimal and harmonic nutrient supply for the young maize plants.

On the basis of the soil samples taken at the end of the experiment and considering the nutrient amounts withdrawn by the crop, we can state that the products enhanced the nitrogen absorbing ability of the plants; however they have not had a positive effect on the rest of the examined nutrients. The nutrient accessibility processes need time for reproduction and the vital activities of microbes. For this reason, we do not recommend to apply these products at the time of sowing.

Keywords: biofertiliser, nutrient content, corn